The 4th East Asia Symposium on Technology of Welding & Joining

(4th EAST-WJ)

Oct.21-23 , 2014, Xi’an, China

Organized by:

Chinese Welding Society (CWS)

Japan Welding Society (JWS)

Korean Welding & Joining Society (KWJS)

Co-organized by:

State Key Laboratory for Mechanical Behavior of Materials

Beijing University of Technology

Contents

Welcome Message ··································································································· 1

Programme at a Glance ···························································································· 6

Programme of Plenary & Parallel Sessions ····························································· 7

Abstracts of Plenary Lectures ··············································································· 11

Abstracts of Parallel Session A: Welding & Joining in Micro-world ························· 16

Abstracts of Parallel Session B: Eco-welding & Manufacturing ······························· 30

Abstracts of Parallel Session C: Welding Behavior & Joint Properties ····················· 40

Abstracts of Parallel Session D: Advanced Arc Welding Physics ······························ 51

List of Attendants ··································································································· 62

1

Welcome Message

Dear colleagues and friends,

We are honored to welcome you to attend the 4th East Asia Symposium on Technology of Welding and Joining (4th EAST-WJ) to be held in Xi’an, China from Oct. 21 to 23, 2014. Initiated by Chinese Welding Society, Japan Welding Society and Korean Welding & Joining Society, the symposium has been successfully held for three times in Shanghai, Nara, and Bexco. We believe that through this platform, we have fully exchanged our academic researches, got better understanding of what’s going on in the welding circle, and extended chances of cooperation in fields of academic and trade. Japan, Korea and China are very important parts of Asia. Besides, we are neighbors. As an old saying in China goes like: a far-off relative is not as helpful as a neighbor. Hence, we have the reason to strengthen communication and coordination in welding & joining related subjects such as talents cultivation, R&D of welding, and trade etc, and to contribute our efforts to the development and growth of Asia. Xi’an is the starting point of the Silk Road. It has a history of more than 3000-year, and 17 dynasties have found its capital in the city. From the ancient city walls of the city you may trace the long-brewed history deposited here. I hope you may enjoy your stay in this beautiful place.

Sincerely yours,

Prof. Zhiling Tian

Symposium Chairman

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International Advisory Committee Chairman:

Prof. Zhiling Tian Vice President of CWS, Deputy President, China Iron & Steel Research Institute Group

Vice Chairman:

Prof. Hiroyuki Kokawa Tohoku University, President of JWS

Prof. Jongwon Yoon Dongeui University, Vice President of KWJS

Secretary General:

Prof. Xiaoyan Li Beijing University of Technology, Vice Secretary General of CWS

Vice Secretary General:

Prof. Manabu Tanaka Osaka University Executive Board Member of JWS

Prof. Sehun Rhee Hanyang University, Auditor of KWJS

Local Organizing Committee

Chairman:

Prof. Changjiu Li, Xi’an Jiaotong University

Member:

Prof. Jianxun Zhang, Xi’an Jiaotong University Prof. Guanjun Yang, Xi’an Jiaotong University Prof. Xide Pan, Xi’an Jiaotong University Prof. Chengxin Li, Xi’an Jiaotong University A. Prof. Zhenguo Sun, Tsinghua University A. Prof. Hui Li, Beijing University of Technology Mrs. Caiyan Huang, Chinese Welding Society

Theme and Topics

Theme: Prospective of Intelligent Welding in East Asia

Topics:

1, Advanced arc welding physics; 2, Eco-welding and manufacturing; 3, Welding and joining in micro-world; 4, Welding behavior & joint properties.

One-day Tour

Oct. 24/Fri, 8:00-17:30: The Terra-cotta→Huaqing Hot Springs

Price: 500Yuan (RMB, based on 12 persons per group. Price includes transportation, entrance fee, English speaking guide, travel insurance and lunch) Please note: 1, Price may change with number of person; Tour fee shall be paid on registration desk. 2, Please provide a photo copy of your

passport (photo page). 3, Route 2 (Qianling, Maoling Mausoleum→Famen Temple) is cancelled due to low number of persons. 4, If you are interested in other route or you have any question for tours, please contact: Ms. Zhao at: 252925224@qq.com. Registration Desk Registration desk will be set up on Oct.21 from 9:00 to 17:30. If you want to join the tour, please confirm it and pay on site. General Information Climate The temperature of Xi’an in October is around 20℃（in daytime）and 10℃ (in the night)。 Electricity Electricity in China is 220 Volts, 50 Hertz. The outlet is three or two flat holes. Currency The currency in China is CNY, 1 Yuan equals to about 0.16 USD. Symposium Secretariat If you have any question please contact: Mrs. Caiyan Huang of Chinese Welding Society: cws86322012@163.com ; Tel:+86-451-86322012

3

About the Venue

Xi’an JiaoTong University Academic Exchange Center-Nanyang Hotel

西安交通大学学术交流中心 南洋大酒店

Address: 1 Xingqing South Rd, Xi’an, China 陕西省西安市兴庆南路 1 号

Tel: 029-87665566; 87665588

Location Map of Nanyang Hotel

Remark: - 15-min-drive to downtown and railway station; - 45-min-drive to airport; - 5-min-drive to exhibition center and coach station

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5

How to Arrive

International passengers will arrive at Xi’an Xianyang International Airport Terminal 2, which is 45km away from the hotel. Passengers shall take airport shuttle or taxi from the airport to the hotel.

It will take about 45 minutes and 120 Yuan by taxi.

Passengers may take Airport Shuttle Line 4 to Jianguo Hotel and then take a taxi to the hotel.

Route details:

For more information about the airport, please visit the Website of Xi’an International Airport: http://www.xxia.com/en/

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Programme at a Glance

Date

Time Activity Venue

Oct.21 Tue.

9:00-18:00 Registration Lobby ( Floor 1)

18:30-20:00 Opening Ceremony & Welcome Reception

Nanyang Garden (Floor 1)

Oct.22 Wed.

8:30-9:10 Plenary Lecture 1 Multifunction Room (Floor 2)

9:10-9:50 Plenary Lecture 2

9:50-10:20 Group Photograph & Coffee break Floor 1

10:20-11:00 Plenary Lecture 3 Multifunction Room (Floor 2)

11:00-11:40 Plenary Lecture 4

11:50-14:00 Lunch Nanyang Garden (Floor 1)

14:00-17:50 Parallel

Session A Parallel

Session B Room 5 (Floor 2)

Room 6 (Floor 2)

18:30-20:00 Banquet Nanyang Garden (Floor 1)

Oct. 23 Thur.

8:30-11:50 Parallel

Session C Parallel

Session D Room 5 (Floor 2)

Room 6 (Floor 2)

12:00-14:00 Lunch Nanyang Garden (Floor 1)

14:00-16:00

Visit to the State Key Laboratory for Mechanical Behavior of Materials (Optional, free of

charge)

Xi’an Jiaotong University (10 minutes walk from the hotel)

Oct. 24 Fri.

8:00-17:30 One day tour to Terra Cotta and Huaqing Hot Spring

(Optional, Register & Pay on Registration Site )

7

Plenary & Parallel Sessions

Time Plenary Lectures

Oct. 22, Wed. Multifunction Room (Floor 2)

Chair: Prof. Xiaoyan Li, Beijing University of Technology

8:30-9:10

Understanding of Inter-particle Bonding for Need-based Design of Microstructure of Thermal

Spray Coating

By Prof. Changjiu Li, Xi’an Jiaotong University

9:10-9:50

Development of In-situ Observation Method for Quantitative Evaluation of Solidification Cracks

during Welding and its Prediction

By Prof. Kenji Shinozaki, Hiroshima University

9:50-10:20 Group Photograph & Coffee Break

Chair: Prof. Yoshinori Hirata, Osaka University

10:20-11:00 Resistance Spot Welding & Joining Technology for Advanced High Strength Steel

By Prof. Sehun Rhee, Hanyang University

11:00-11:40 Research and Development on Heterogeneity and Gradient Issues in Welded Joint

By Prof. Jianxun Zhang, Xi’an Jiaotong University

11:50-14:00 Lunch (Nanyang Garden,Floor 1)

Parallel Session A: Welding & Joining in Micro-world

Oct.22,Wed,Room 5 (Floor 2)

Chair: Prof. Mingyu Li, Harbin University of Technology (Shenzhen Graduate School)

14:00-14:20

[Invited Presentation]

Micro-joining Applied to Eco Electronics Packaging

By Prof. Yasuo Takahashi, Osaka University

14:20-14:40 Electroplating of Cu in TSV and Properties of Solder Bump

By Prof. Jae Pil JUNG, University of Seoul

14:40-15:10

Rapid Formation and Phase Transformation of Intermetallic Compounds Interconnection in

Three-dimensional Electronic Packages

By Prof. Yanhong Tian, Harbin Institute of Technology

15:10-15:30

Numerical Analysis and in-situ Observation of Keyhole Dynamics and Porosity Formation during

Spot Welding by Fiber Laser for Aluminum

By Prof. Qiaofeng Zhou, Osaka University

15:30-15:50 Fine-grained Substrate Promoting Kirkendall Voiding in Sn/Cu Joints

By Dr. Chun Yu, Shanghai Jiao Tong University

15:50-16:10 Coffee Break

Chair: Prof. Jae Pil Jung, University of Seoul

16:10-16:30

[Invited Presentation]

Characteristics of Nanocomposite Paste for LED Package with Reflow Process

By Prof. Seung-Boo Jung, Sungkyunkwan University

8

16:30-16:50

Twin-induced Ultra-high Thermal Conductivity of Sintered Ag Nanoparticles for High Power

Density Electronic Packaging

By Prof. Mingyu Li, Harbin Institute of Technology (Shenzhen Graduate School)

16:50-17:10 A Study on the Laser Brazing Characteristics of Mg/Steel Dissimilar Joints

By Dr. Sook-Hwan Kim, Research Institute of Industrial Science & Technology

17:10-17:30 Ultrasonic Weldability of Al ribbon to Cu Sheet and Joint Formation Behaviors

By Prof. Guifeng Zhang, Xi’an Jiaotong Unviersity

17:30-17:50 Materials Laser Welding/joining at Microscale and Nanoscale

By Associate Prof. Lei Liu, Tsinghua University

18:30-20:00 Banquet (Nanyang Garden, Floor 1)

Parallel Session B: Eco-welding & Manufacturing

Oct. 22,Wed Room 6 (Floor 2)

Chair: Associate Prof. Lianyong Xu, Tianjin University

14:00-14:20 [Invited Presentation]

In-situ Observation of Microstructural Evolution in Simulated Coarse-grained HAZ of Bainitic Steel By Associate Prof. Hidenori Terasaki, Osaka University

14:20-14:40 Welding and Joint Surface Nanocrystallization of 7A52 Aluminum Alloy

By Prof. Furong Chen, Inner Mongolia University of Technology

14:40-15:10 Effects of Martensite on Cold Cracking in 600MPa Grade FCA Weld Metals

By Prof. Nam Hyun KANG, Pusan National Univ.

15:10-15:30 Pinless Friction Stir Welding of Aluminum Alloy: from Spot Weld to Butt and Lap Weld

By Prof. Wenya Li, Northwestern Polytechnical University

15:30-15:50 Evaluation of Hot Cracking Susceptibility using Trans-Varestraint Test with Laser Welding

Assistant Prof. Kota Kadoi, Hiroshima University

15:50-16:10 Coffee Break

Chair: Prof. Nam Hyun Kang, Pusan National University

16:10-16:30

[Invited Presentation]

Process mechanism of ultrasonic vibration enhanced friction stir welding By Prof. Chuansong Wu, Shandong University

16:30-16:50 Fatigue Life of the Repair TIG Welded Hastelloy X Superlloy

By Prof. Eung-ryul BAEK, Yeungnam University

16:50-17:10 Investigation on Friction Hydro-pillar Processing by Experiments and Numerical Simulation

By Associate Prof. Lianyong Xu, Tianjin University

17:10-17:30 Numerical Simulation for Fluid Flow around A Tool of FSW

By Associate Prof. Fumikazu Miyasaka, Osaka University

18:30-20:00 Banquet (Nanyang Garden, Floor 1)

Parallel Session C: Welding Behavior & Joint Properties

Oct. 23, Thur. Room 5 (Floor 2)

Chair: Prof. Huaping Xiong, Beijing Institute of Aeronautical Materials

8:30-8:50 [Invited Presentation]

Hierarchical Damage Simulation for Structural Performance-Based Material Design By Associate Prof. Mitsuru Ohata, Osaka University

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8:50-9:10

Three-dimensional Porosity-induced Fatigue Cracking in Hybrid Laser Welded Al Alloys via High-resolution SR-μCT

By Prof. Shengchuan Wu, Southwest Jiaotong University

9:10-9:30 Reviews on Nucleation Mechanisms of Acicular Ferrite

By Dr. Hee Jin KIM, KITECH

9:30-9:50 Strengthening of Spot Welded Lap Joints by New Hardened Zone

By Assistant Prof. Takanori Kitamura, Kyushu Institute of Technology

9:50-10:10 Application of Narrow-Gap Welding Technology of Turbine Welded Rotor

By Dr. Xia Liu, Shanghai Turbine Plant of Shanghai Electric Power Generation Equipment

10:10-10:30 Coffee Break

Chair: Dr. Hee Jin Kim, KITECH

10:30-10:50

[Invited Presentation]

Interfacial oxidation of aluminum at liquid alloy/sapphire interfaces under ultrasonic filed and its application in joining

By Prof. Jiuchun Yan, Harbin Institute of Technology

10:50-11:10 Deterioration Characteristics of Anti-corrosion Paint Coating on welded Part of Structural Steel

By Dr. Mikihito HIROHATA, Nagoya University

11:10-11:30 Prediction of Proper Arc Welding Condition by Artificial Neural Network for Automotive Industry

By Mr. Seunghwan BAE, Chungbuk National University

11:30-11:50

Microstructure and Mechanical Properties of Dissimilar Joints of Ti-Al Intermetallics with Ni-based Wrought Superalloy By Prof. Huaping Xiong, Beijing Institute of Aeronautical Materials

11:50-12:10

An Investigation of Liquid Metal Embrittlement in Resistance Spot Welding of High Manganese TWIP Steels

By Prof. Yeong Do PARK,DONG-EUI University

12:20-14:00 Lunch (Nanyang Garden, Floor 1)

14:00-16:30 Visit to the State Key Laboratory for Mechanical Behavior of Materials(Optional, 10 minutes walk)

If you hope to visit the lab, please meet in the lobby at 14:00 and we’ll guide you there.

Parallel Session D: Advanced Arc Welding Physics

Oct. 23, Thur. Room 6 (Floor 2)

Chair: Prof. Shujun Chen, Beijing University of Technology

8:30-8:50

[Invited Presentation] Visualization of Arcs by Time-dependent Monochromatic Images in MIG/MAG Welding

By Prof. Manabu Tanaka, Osaka University

8:50-9:10

Influence Mechanism of Process Parameters on Keyhole-induced Porosity Formation Based on 3D Transient Modelling

By Associate Prof. Fenggui Lu, Shanghai Jiao Tong Universit

9:10-9:30 Theoretical Analysis of Variable Polarity Arc Welding of Aluminum

By Mr. Jungjae LEE, Chungbuk National University y

9:30-9:50 Numerical Simulation of Arcs with Short-circuiting Transfer in GMA Welding

By Mr. Kazuya Ishida, Osaka University

9:50-10:10 Comprehensive simulation of Laser Cladding Process of A Nickel-based Superalloy

By Dr. Pulin Nie, Shanghai Jiao Tong University

10

10:10-10:30 Coffee Break

Chair: Prof. Manabu Tanaka, Osaka University

10:30-10:50 [Invited Presentation]

Effects of Profile Force on Ductility of UHSS Resistance Weld Joint (Part 1) By Prof. Hee Seok CHANG, Myongji University

10:50-11:10

Study of the Flow and Temperature Distribution of Molten Pool in Electromagnetic Controlled Molten Pool Welding Process

By Associate Prof. Shoichi MATSUDA, University of the Ryukyus

11:10-11:30

A Deeply Description of Welding Plasma Arc – the Separability and Measurement of Arc Components

By Prof. Shujun Chen, Beijing University of Technology

11:30-11:50 Time-resolved X-ray Study of Thermodynamic non-Equilibrium in Weld Solidification

By Associate Prof. Hidenori Terasaki, Osaka University

11:50-12:10 Porosity Control in Wire Plus Arc Additive Manufacturing (WAAM) of Aluminium-copper Alloy

By Dr. Baoqiang Cong, Beihang University

12:20-14:00 Lunch (Nanyang Garden, Floor 1)

14:00-16:30

Visit to the State Key Laboratory for Mechanical Behavior of Materials(Optional, 10 minutes walk)

If you hope to visit the lab, please meet in the lobby at 14.00 and we will guide you there.

Please note: For plenary session, presentation time is 35 minutes, plus 5 minutes for discussion. For parallel session, presentation time is 15 minutes, plus 5 minutes for discussion.

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List of Abstract--Plenary Lectures

12

Understanding of Inter-particle Bonding for Need-based Design of

Microstructure of Thermal Spray Coating Chang-Jiu Li

School of Materials Science and Engineering, Xi’an Jiaotong University, China

E-mail: licj@mail.xjtu.edu.cn

Abstract:

Thermal spray processes are well established processes which are employed to deposit different types of

protective and functional coatings such as wear resistance and thermal barriers applicable to different industrial

fields. The coatings are primarily deposited by stacking molten or semi-molten spray particles through rapid

solidification. The inter-particle bonding in the coating determines its physical, thermal and mechanical properties

and subsequently their performances. The formation of the inter-particle bonding upon spray particle impact

depends primarily on the inter-reaction of impacting particle with the underlying substrate or previously deposited

particles, which is influenced by the surface conditions of substrate and the parameters of spray particles.

Recently, it was revealed that the inter-splat bonding formation can be controlled by the deposition

temperature during spray process. Accordingly, we found that there is a critical deposition temperature for

impacting molten droplet to form the bonding with the underlying identical substrate surface. Moreover, the

critical temperature is positively related to the melting point of spray materials. The further investigation based on

one dimensional heat transfer model suggests the existence of an intrinsic critical interface temperature for

bonding formation before solidification of rapid spreading melt over a solid surface. It will be demonstrated that

based on the critical temperature concept for the bonding formation the deposits with different microstructures

from a porous one to a fully dense one, which are required to fulfill the versatile performance requirements, can be

designed and created. Moreover, such concept can be utilized to broaden the application of thermal spray

processes to other different fields.

13

Development of In-situ Observation Method for Quantitative Evaluation of

Solidification Cracks during Welding and its Prediction Kenji Shinozaki

Dept. of Mechanical Science and Engineering, Hiroshima University, Japan

E-mail: kshino@hiroshima-u.ac.jp

Abstract:

Solidification cracking during welding is very serious problem for practical use. Therefore, there are so many

reports concerning solidification cracking. Normally, solidification cracking susceptibility of material is

quantitatively evaluated using Trans-Varestraint test. On the other hand, local solidification cracking strain was

tried to measure precisely using in-situ observation method, called MISO method about 30 years ago.

Recently, digital high speed video camera has developed very fast and its image quality is very high.

Therefore, we have started to observe solidification crack using in-situ observation method during laser welding.

There are some parameters such as BTR (Brittle Temperature Range), ductility curve and so on for

evaluating solidification cracking susceptibility of weld metal. We have developed the BTR and the ductility curve

at the temperature range from liquidus and solidus using in-situ observation method. At same time, we have tried

to calculate high temperature strain behavior during solidification on several welding methods. Then we have tried

to predict the occurrence of solidification crack during several welding conditions. I will introduce these results.

14

Resistance Spot Welding & Joining Technology for

Advanced High Strength Steel

Sehun Rhee1,* Junghyun Shim, Mohd Faridh

1Department of Mechanical Engineering, Hanyang University,

17 Haengdang-dong, Seongdong-gu, Seoul 133-791, Korea

Abstract:

Resistance spot welding (RSW) is one of the important manufacturing processes to join the

sheet metals in the automotive industry. In joining a car body, the welding for advanced high

strength steel (AHSS) was frequently used. Also, car makers tried to improve weldability of AHSS,

since the weldability of AHSS is generally not so good. To overcome these problems new

approaches will be proposed. In this work, additional cover sheet method and constant power

control method and hemispherical concave hole method are introduced for joining the high strength

steel. Finally the experimental results will be shown in figures.

Keywords: resistance spot welding, advanced high strength steel, weldability.

*Corresponding author. Tel.: +82-2-2220-0438, Fax: +82-2-2299-6039

Email address: srhee@hanyang.ac.kr (S. Rhee)

15

Research and Development on Heterogeneity and Gradient Issues in

Welded Joint

Zhang Jianxun

State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering in Xian Jiaotong University, Xian, China

Abstract:

Therefore the researches on microstructure, residual stress and properties of welded joints are

extremely important basic scientific issues. Metals welded with arc welding, especially high energy

beam welding, have always had to suffer a strong gradient thermal cycle, which causes

synchronously heterogeneous microstructure, mechanical properties and residual stress with larger

gradient feature. The performance of welded joint will be hybrid affected by the heterogeneous

microstructure, mechanical properties and residual stress.

The researches and development on heterogeneity and gradient issues in welded joint are

summarized, especially the works in the Welding Research Institute of Xian Jiaotong University.

Main research activities reported on the heterogeneity and gradient issues in the welded joint

involve the importance of thermal cycles in welding, the token of the heterogeneous microstructure,

mechanical properties and residual stress, the scale effects of weld seam and HAZ, their composite

effects on performance of welded joint, the numerical simulation in welding distortion and residual

stresses. However, researches on welded joint performance with large gradient characters are less

comprehensive than that on homogeneous materials. Especially, the high energy beam welded joints

contain large microstructure and properties gradient and sharp residual stress gradient and scale

effects of welding seam and HAZ.

The investigations on the mechanical behaviors of high energy beam welding joints are a

frontier topic needing to further discussion. In order to understand the effects of nonlinear

microstructures on the plastic damage behavior of laser deep penetration welded joint, a

multi-specimen tensile method by measuring the micro void density was applied to estimate the

plastic damage behavior for Ti-6Al-4V alloy. The damage mechanism presents the pattern of

microvoid nucleation, growth and coalescence. The microvoid density under different loading has a

great relationship with the gradient distribution of microstructure in the welded joint. The growth

rate of microvoids in the weld metal, heat affected zone and base metal is also related to the loads.

When the load is lower, the damage in the weld metal is larger than that in the heat affected zone

and base metal, and when the load is higher, the growth rate of the microvoid in heat affected zone

and base metal is higher than that in weld metal. The grain size in weld metal has small effects on

plastic damage, but the great gradient of the grain size in heat affected zone may delay the plastic

damage evolution.

16

Parallel Session A:

Welding & Joining in Micro-world

17

Micro-joining Applied to Eco Electronics Packaging Yasuo Takahashi,

JWRI, Osaka University, Japan

Abstract :

Electronics is necessary for reducing waste of natural resource and preserving global environment sustainably.

Electronics technology is very helpful for power controlling and information technology (IT). Electronics devices

and modules are made of various kinds of materials, which have to be joined and fabricated so that they can show

the high performances for global sustainability. The trend of micro-joining technology applied to eco electronics

packaging is, therefore, reviewed and some examples of its fundamental studies are reported. For example, flip

chip bonding (FCB) for high density chip size packaging, ultrasonic bonding for power device wiring, and

interconnection of electric pad (contact film) for the next generation compound semiconductor, silicon carbide

(SiC), are described.

Eco electronics packaging: Eco (Environmentally Conscious) electronics packaging can be defined by 1)

Contributing to energy saving and creating renewable energy. 2) Taking into account LCA (life cycle assessment),

i.e., forward (production) and inverse (recycling) processes should be combined properly without toxic (hazardous)

substances. 3) Bonded materials can be recycled toward zero-emission. 4) Contributing to IT and environmental

revolutions. 5) Low cost and high reliability. 6) Downsizing for IT and upgrading for power controlling. And also

7) Low temperature bonding should be applied, i.e., transition from liquidus to solidus is necessary, or even if

solder is used, the thermal toughness should be ensured after bonding.

Downsizing: Downsizing is necessary for high density packaging in IT field, i.e., three dimensional (3D)

packaging is now developed. FCB is very useful as one of gang bonding methods to obtain a lot of small connects

and to contribute the chip size packaging as well as BGA (Ball Grid Array). Numerical simulation of ultrasonic

FCB will be reported.

Upgrading: Power control for hybrid vehicles needs not only upgrading of power module but also

downsizing, i.e., power devices should be more compact and more powerful with high reliability. Ultrasonic

bonding is applied to electric wiring around power device within the package.

Nano interconnection: SiC is one of compound semiconductors. SiC devices are made of various

materials. The electric current flows through bonded areas. A strong bonding is not always a good electric contact

(interface). The electric pad (contact film) on SiC needs to have a low resistance. SiC has Si- (front) and C- (back)

surfaces. The contact reaction differs between C- and Si-surfaces. Also, the contact film should be changed

between n-type SiC and p-type SiC. The interface reaction is very important to obtain a good contact properties.

Keywords: Electronics packaging, Micro-joining, Interconnection, Ultrasonic bonding, Power device, Chip size

packaging (CSP)

Email address: takasy@jwri.osaka-u.ac.jp (Y. Takahashi)

18

Electroplating of Cu in TSV and Properties of Solder Bump

Dohyun Jung1, Santosh Kumar1, Soonjae Lee1, Jae Pil Jung1*

1Dept. of Materials Sci. and Eng., University of Seoul, Seoul 130-743, Korea

*corresponding author; jpjung@uos.ac.kr

Abstract:

For high density packaging, Cu electroplating in TSV (through-Si-via) and characteristics of solder bumps

were investigated in this study. A straight via having a diameter of 60 μm and depth of 120 μm were drilled in a Si

wafer by DRIE (deep reactive ion etching) process. Cu was filled in the via by electroplating where the current

waveform of a periodic pulse reverse (PPR) was applied. The low alpha solder bump having a composition of

Sn–1.0Ag–0.5Cu (SAC105) and a diameter of 80 μm was formed by reflow on a Cu-filled TSV. In

three-dimensional (3-D) packaging, the solder bumps are very close to the active Si devices, where even the low

energy alpha ray can induce soft error, which needs to choose the low alpha solder in packaging. For estimating

the shear force of the solder bump, high speed shear tester (Dage 4000HS) was used, and for the fracture mode

analysis, scanning electron microscopy (FE-SEM) was employed. As experimental results, Cu filled into TSV

showed a typical bottom up filling. The shear force of low alpha SAC105 bump increased with increasing shear

speed from 10 to 500-1,000 mm/s, which depends on kinds of bump pads. Brittle fracture tendency increased with

increasing shear speed. The properties of low alpha SAC105 solder were comparable to those of normal solder.

19

Rapid Formation and Phase Transformation of Intermetallic Compounds

Interconnection in Three-dimensional Electronic Packages

Yanhong Tian*, Baolei Liu, Chunqing Wang

State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology,

Harbin, China

Abstract:

Three-dimensional (3D) package is considered as the predominant interconnection technology in the coming era

of semiconductor industry due to its minimized size, high density, excellent electrical-mechanical performance

and low power consumption. One important requirement for the bonding materials and processes in 3D

integration application is to enable the repeated stacking of additional layers without remelting the joints. The

strength of those solder joints depends greatly on the interfacial intermetallic compounds formed at the joint

interfaces. In particular, if a thin Sn layer is used to join two Cu through-Si vias (TSVs) for the 3-D

interconnections, this thin Sn layer would be consumed substantially and form thick Cu–Sn compounds. As a

result, the Cu–Sn compounds and the dominant phase of the 3-D IC connections play a critical role in the

electrical resistance and the mechanical strength of the junction of two Cu TSVs. Recently, this technological

challenge has been solved by forming the high-melting-point joints through transient liquid phase (TLP) bonding

or eutectic bonding process. However, a common drawback for these processes is that they all necessitate a very

long bonding time, up to tens of minutes, which will lead extra thermal stress and seriously affect the reliability of

packaging system. Therefore, the development of rapidly forming process of IMCs or high reliability joints at low

temperature is imperative.

In this paper, the phase transformation and grain orientation of Cu-Sn and Cu-In intermetallic compounds

under low temperature bonding process was investigated, meanwhile, a new approach of rapid fabrication of

intermetallic compounds (IMCs) solder joints at ambient temperature was proposed. Firstly, the Cu/Sn/Cu

structures were bonded with different bonding time at various temperatures in argon gas atmosphere. Scanning

electron microscope (SEM) and Energy-dispersive X-ray (EDX) were used to observe the interfacial

microstructures in joints and Electron Back Scattering Diffraction (EBSD) was used to identify the grain

orientations.Secondly, microstructure evolution and phase transformation of Cu-In intermetallic compounds

(IMCs) in Cu/In/Cu joints formed by Solid-Liquid Interdiffusion (SLID) Bonding at 260°C and 360°C were

investigated respectively.Lastly, a new method of rapid fabrication of intermetallic compounds (IMCs) solder

joints at ambient temperature was investigated. High shear strength Cu/Sn/Cu solder joints were obtained by using

different electric currents 0.8KA, 0.9KA, 1.0KA, and 1.2KA for only about 0.2s. The Sn foils with the thickness

of 10μm were used as solders. The results showed that with the current intensities increasing from 0.8KA to

1.2KA, the thickness of IMCs, Cu6Sn5, increased from less than 1μm to 4.2μm for 0.2s, which was induced by

thermoelectric coupling interfacial interaction at the liquid solder/solid metallization interface. In addition, amount

of dendritic Cu6Sn5 distributed in the Sn matrix at the bottom right corner of solder joint under the current

intensity of 1.2KA, which was caused by the current crowding effects. Lastly, the share strengths of Cu/Sn/Cu

solder joints under the rapid bonding process were improved with the bonding current increasing. The share

strength was up to 51.9MPa at 1.2KA.

20

Numerical Analysis and in-situ Observation of Keyhole Dynamics and Porosity

Formation during Spot Welding by Fiber Laser for Aluminum

Q. Zhoua,*

, Y. Honshoua, H. Mori

a , F. Miyasaka

b, Y. Uemura

c, Y. Kawahito

c, M. Mizutani

c and

S. Katayamac

aOsaka University, Graduate School of Eng., Department of Management of Industry & Technology,

2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan bOsaka Univ., Department of Adaptive Machine Systems, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan

cOsaka Univ., Joining and Welding Research Institute, 11-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan

Abstract:

In the case of welding for aluminum alloys, large distortion occurs due to its large thermal conductivity and

thermal expansion ratio. From the view point of heat input suppression, laser beam welding (LBW) is one of

effective approach to put the alloys into practical use. However, another big problems to adopt the alloys as

structural materials with welding is weld defects such as porosity, hot cracking, and so on [1]. Thus, development

of the method to make sound weld joints without defects and to draw suitable welding conditions is demanded, in

order to improve productivity due to breaking away from current search methods by trial and error. Therefore, as

the first stage, in order to clarify the mechanism of porosity in weld metal on Laser Beam Welding(LBW) process

and suggest proper welding conditions without any defects, the numerical analysis based on fluid dynamic

theories and in-situ observation using X-ray transmission real-time imaging system were conducted. In this study,

the behaviour of keyhole and microbubbles formation during LBW process was calculated by the developed

analysis model previously described. Figure1 shows the cross sectional view of calculated LBW welds and actual

cross sectional image of spot welds obtained by the imaging system. A keyhole was formed due to lineal energy,

which is corresponding to laser irradiation, put into the substrate, as demonstrated in (a). In addition, micobubbles

were recognized in the middle of weld metal after solidification, as indicated in (b). As compared between the

calculation results and its in-situ observation in (c), the calculation results for keyhole dynamics were in good

qualitative agreement with the experimental ones.

Keywords: Aluminium, Laser beam welding, Numerical analysis, Microfocused X-ray transmission in-situ

observation

Fig. 1 Cross sectional view of keyhole and porosity formed during laser beam welding for aluminium. (a) Calculation of keyhole dynamics, (b) Calculation of porosity formation, (c) In-situ observation.

References

[1] Y.Kawahito, N.matsumoto, Y.Abe and S.Katayama, “Relationship of laser absorption to keyhole behavior in

high power fiber laser welding of stainless steel and aluminum alloy” Journal of Materials Processing

Technology, vol.211, 1563-1568 (2011).

*Corresponding author. Tel. :+81-6-6879-3652

Emal address :q-zhou@mit.eng.osaka-u.ac.jp (Q.F. ZHOU ).

(a) (b) (c)

21

Fine-grained Substrate Promoting Kirkendall Voiding in Sn/Cu Joints

Chun Yu a,b

, Jieshi Chen a, Yang Yang

c, Jijin Xu

a, Junmei Chen

a, Hao Lu

a, b, *

aSchool of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China

bKey Lab of Shanghai Laser Manufacturing and Materials Modification, Shanghai 200240, PR China

cPackaging Engineering R&D Department, SanDisk Semiconductor (Shanghai) Co., Ltd., Shanghai 200241, PR China

Abstract:

Formation of Kirkendall voids was studied by employing Sn and various Cu substrates. After aging at 180 ℃,

the voids did not appear at Sn/high-purity (HP) Cu interface, while a number of voids were observed both at

Sn/electroplated (EP) Cu, and Sn/vacuum sputtered (VS) Cu joints. The size of voids formed at the Sn/VS Cu was

smaller relative to that at the Sn/EP Cu. The VS Cu has the finest grains, and the EP Cu follows, while the HP Cu

has the coarsest grains. The fine-grained VS Cu could supply more diffusion paths for Cu atoms diffusing out of

the Cu/Cu3Sn interface, generating more vacancy flux; in addition, the fine grains would grow during thermal

aging, releasing energy to promote void nucleation. Therefore, fine-grained Cu substrate would promote

Kirkendall voiding

.

Keywords: Kirkendall void; Grain size; Electronic materials; Interface; Copper

E-mail: shweld@sjtu.edu.cn, Tel. / Fax: +86-21-34202548

22

Characteristics of Nanocomposite Paste for

LED Package with Reflow Process

Kwang-Seok Kim*, Won-Chul Moon**, Dae Up Kim***, Seung-Boo Jung*

*School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, Korea

** SMT Korea Co., Ltd, Hwaseong 445-812, Korea

*** Korea Institute of Industrial Technology, Jeonju 561-202, Korea

Abstract:

Reliability of light-emitting diode (LED) package depends on the thermal resistance of thermal interface mat

erials and the die attach quality of bonding materials, leading failure in the operation. The ECO-trace reflow proce

ss as well as these interconnect materials has a pivotal role in thermal management of the LED package by providi

ng the superior heat dissipation from LED chips to heat sink and stable thermal uniformity. Carbon nanotube (CN

T) is one of the promising conductive fillers due to its reinforcement and excellent thermal conductivity. Conducti

ve nanocomposite paste containing multi-walled CNT (0, 1, 2, 3 wt.%) mixed with metal nanoparticles dispersing

in solvent was employed to investigate the influence of CNT on thermal and mechanical properties of the nanoco

mposite paste. The reflow temperature profiles were varied to understand the effects of reflow conditions on the

electrical/mechanical/thermal characteristics of nanocomposite joints with special tracer. Differential scanning cal

orimetry was carried out to analyze thermal behaviour of the nanocomposite paste and microstructural evolution

was observed using field emission scanning electron microscopy. Thermal conductivity of the nanocomposite past

e was measured by the thermal constants analyzer with the Kapton insulated sensor, and the relative density of the

paste was statistically analyzed by the Brunauer-Emmett-Teller method.

Bare LED chips were attached on the silver-finished heat slug using the nanocomposite paste by a reflow pro

cess. The bonding strength of the nanocomposite joint was evaluated by a low-speed die shear test. Mounted L

ED packages were fabricated on the metal-based printed circuit board and thermal resistance of the nanocomposit

e paste in the LED package was measured by T3ster thermal transient tester. The total LED luminous flux was me

asured by an integrating sphere system and the temperature profile of the LED package module was detected by a

n infrared camera. When the nanocomposite paste was sintered at higher temperatures or had larger multi-walled

CNT composition rates, its thermal conductivity and fracture energy increased.

The results indicated that the ECO LED package fabricated by the nanocomposite paste showed further

improved heat dissipation and lumen degradation through the low thermal contact resistance and high thermal

conductivity.

Key Words : Multi-walled carbon nanotube, Metal-matrix nanocomposite, Ag nanoparticle, Thermal conductivity,

Heat dissipation

23

Twin-induced Ultra-high Thermal Conductivity of Sintered Ag Nanoparticles

for High Power Density Electronic Packaging Shuai Wang, Mingyu Li*

State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology Shenzhen Graduate

School, Shenzhen, China 518055

*myli@hit.edu.cn

Abstract:

Rapid pressureless low temperature sintering of Ag nanoparticles for bonding is achieved. Organic shells

adsorbing on the surface of Ag nanoparticles to stabilize them are thinned to be a sparse protecting layer.

Numerous coherent twin boundaries formed in sintered Ag nanoparticles with a grain size of 21 nm induce

ultra-high thermal conductivity (229 W/m·K), which overcomes the intrinsic defect that metals with nano-sized

grain generally cause a pronounced decrease in thermal conductivity because of the grain boundary scattering

effect.

Keywords:Ag nanoparticle; sintering; bonding; thermal conductivity; twinning

Fig. 2. (a) Thermal conductivity and porosity of

Ag nanoparticles with thin organic shells sintered

for 20 min as a function of sintering temperature.

(b) Shear strength of joints as a function of

sintering time using the Ag nanoparticles with

thin organic shells sintered at 150 °C and 200 °C.

Inset: SEM (scanning electron microscopy)

image of sintered Cu-to-Cu joint.

Fig. 1. (a) Schematic diagram of sintering

process of Ag nanoparticles with thick organic

shells and (b) that with thin organic shells. (c)

TEM image of Ag nanoparticles sintered at

200 °C for 20 min with thick organic shells and

(d) that with thin organic shells. (e) and (f) are

the low magnification TEM images of (c) and (d)

respectively. (g) TEM image of initial Ag

nanoparticles.

24

A Study on the Laser Brazing Characteristics of

Mg/Steel Dissimilar Joints Sook-Hwan Kim*, Mok-Young Lee*, Y. Zhou**, Jong-Won Yoon**

*System Solution Research Center, RIST, Pohang 790-330, Korea

**Department of Mechanical & Mechatronics Eng., Univ. of Waterloo, ON, Canada

***Department of Materials Science & Eng., DongEui Univ. Busan 614-714, Korea

Abstract: Within the last years there was a rising interest in dissimilar metal combinations. In automotive and aviation

industries, the development of dissimilar material joints is a consequent advancement of the concept of tailoring

blanks. Besides a further optimized material exploitation concerning the mechanical properties, additionally offers

benefits under functionality requirements.

In past few years, many researches focused on joining aluminum to steel and aluminum to titanium,

involving solid state joining, reactive wetting or laser welding. Nevertheless, the major work in this aspect is the

development of the laser process. Laser brazing and laser welding-brazing technologies are realized for well

joining dissimilar materials due to the combination of furnace brazing and laser welding. With a much localized

energy input and precise control of laser beam energy, a high joining speed and accompanying high cooling rates

are carried out. Laser brazing and welding-brazing successfully prevent an excessive formation of intermetallic

phases. The formation of intermetallic layers can be limited to a size below 10 µm which leads to desirable

mechanical properties.

The melting points of Mg and Fe are 649 ℃ and 1538 ℃, respectively. The great difference in the melting

points between these two kinds of metals poses the difficulty in melting them at the same time during fusion

welding. Moreover, they do not react with each other. Therefore, joining Mg alloys to steels by fusion welding

processes is very difficult. Laser welding-brazing and laser brazing all are better approaches to join magnesium to

steel.

Thus, laser brazing between commercially Al coated steel and Mg alloy (AZ31B) has been carried out in the

Mg-based and Al-based insert metals. The brazing bonds have been evaluated using light microscopy, electron

probe microanalysis (EPMA), X-ray diffraction (XRD) technique and tensile shear testing. Light microscopy

shows that different intermediate layers are formed in the reaction zone, and these layers changes with a kind of

insert metals. EPMA revealed that, at any particular insert metal, Mg-rich phases (intermetallic phases) formed in

cell boundary of the Mg alloy side, but original coated layer remained in the steel side.

This microanalysis also indicated different step formations in the concentration profile of Al, Mg, Zn and Si

over different composition ranges in the fusion zone indicating formation of intermetallic phases that were

detected by XRD. Brittle intermetallic phases lower the strength and ductility of the brazed couples significantly.

Best room temperature tensile shear fracture load, approx = 520kg. has been obtained at Mg-5.9Al-0.8Zn-0.55Mn

due to minimal deleterious effects.

Key Words : Laser Brazing, Dissimilar Metal, Tensile Shear Test

*Corresponding author. Tel.: +82-54-279-5453, Fax: +82-54-279-6888.

Email address: weldksh@rist.re.kr (S.H. Kim).

25

Ultrasonic Weldability of Al Ribbon to Cu Sheet and

Joint Formation Behaviors

Guifeng Zhanga,b

*, Zhonghao Hengb, Kazumasa Takashima

b, Kouta Mizawa

b,

and Yasuo Takahashib

a State Key Laboratory for Mechanical Behavior of Materials,

Xi’an Jiaotong University, Xi’an 710049, China b Joining and Welding Research Institute, Osaka University, Ibalaki, 567-0047, Japan

Abstract: This work aims to investigate the ultrasonic weldability of Al ribbon (width 2.0 mm × thickness 0.2 mm) to

Cu sheet (thickness 1.0 mm) and to understand joint formation behaviors by examining joint macro- and

micro-structures, and also bond-fracture behavior. The bonding tool (sonotrode tip size) was 2.0 mm × 1.0 mm.

For the selected conditions of 20 W power, 30 N clamping force, 0.1-1.0 s bonding time, it was found that sound

lap joint could be readily obtained when bonding time reached and exceeded 0.4 s. After tensile lap shear testing

(pulling lap-bonded Al ribbon in the direction parallel to interface), these sound joints fractured within Al ribbon,

close to clamping jig or bonded area, but not along interface, indicating that (i) oxide film was removed well from

the base metal surfaces, and (ii) the detrimental effect of metallic compounds can be prevented even for the long

bonding time of 1 s. It was suggested from microstructure observation that an intimate contact was achieved well

at most interface, except for boundary region, showing detectable interlocking. Even for failed joint, adhered Al

could be clearly observed on Cu side. Based on the fracture surface, fracture position and microstructure, the joint

formation could be described as (i) slipping and initial mechanical contacting (or frictional adhesion) in large area,

and (ii) subsequent metallurgical bonding in partial areas at both Cu/Al (between Cu surface and the initially

adhered thin Al layer) and Al/Al (between the initially adhered thin Al layer and Al ribbon body) interface

formation, assisted primarily with frictional slipping and detectable transversal deformation, respectively.

Keywords: ultrasonic welding; aluminum ribbon, copper sheet, frictional slipping, mechanical bonding,

metallurgical bonding

Corresponding author. Tel.:+86-29-82668807, Fax: +86-29-82668807.

Email address: gfzhang@mail.xjtu.edu.cn (Guifeng Zhang)

26

Materials Laser Welding/joining at Microscale and Nanoscale

Guisheng Zou1, Lei Liu1,2, Zhenguo Sun1, Hailin Bai1, Aiping Wu1, Y. Norman Zhou1,3

1Department of Mechanical Engineering, Tsinghua University, Beijing, , China

2The State Key Laboratory of Tribology, Tsinghua University, Beijing, China

3Department of Mechanical & Mechatronics Engineering, University of Waterloo, Waterloo, Canada,

Email: zougsh@tsinghua. edu.cn, liulei@tsinghua.edu.cn

Keywords: laser, nanojoining, microjoining, femtosecond laser

1. Introduction

Laser microjoining/welding and microjoining/welding technology has been applied in many industries, such

as defense, life science, medical, microelectronics etc. As the development of material science and product design,

laser microjoining/welding technology needs to be developed accordingly. In this presentation, laser induced

microjoining and nanojoining have been performed, including laser microbrazing of CNT yarn, laser micro braze

welding of Pt to stainless steel, laser directly welding of glass , laser welding of nano-Ag wires and laser

brazing-welding of nano- Ag particle and nano-Pt particle.

2. Experimental procedure

(1) For laser microbrazing of CNT yarn

High strength and conductive super-aligned CNT yarns are made from the produced carbon nanotube wafer by

a twisting and shrinking method. The brazing alloy used here is a ternary Ag-Cu-Ti alloy with a chemical

composition of 3 wt. % Ti, 62.2 wt. % Ag and 34.8 wt. % Cu. A Nd: YAG pulse laser is used as the laser source

with a pulse energy of 4.1J and repetition rate of 10Hz.

(2) For laser micro braze welding of Pt to stainless steel

Pt-10 pct Ir (wt pct) wire and cold-worked 316 LVM SS wire, both of 0.38-mm diameter, were used in this

study, and a simple rectangular pulse profile was used for all welds[1]

.

(3) For laser directly welding of glass

Fused silica glass was directly welded by using a femtosecond laser (50fs, 1kHz, max. 4mJ/pulse, Gaussian

beam profile).

(4) For laser joining of nanoparticles

Laser brazing-welding of nano-Ag particle and nano-Pt particle was directly joined through the femtosecond

laser irradiation.

(5) For laser welding of nano-silver Ag wire

Nano-Ag wire was directly welded through the femtosecond laser dirrect irradiation

3. Results and Discussion

Figure 1 shows micro brazing of CNT yarn by using a Nd:YAG pulsed laser. With increase of pulse number, the

joint strength increased and peaked at 55 pulses. The cross section of the micro brazed joint showed that the CNT

yarn was completed surrounded by the AgCuTi filler metal. The Ti element riched at the periphery region of the

CNT yarn indicated that Ti-C compounds formed which contributed to the joint strength.

27

Figure 1 Laser micro brazing of CNT yarn

Figure 2 shows micro braze welding of Pt to stainless steel. The Pt and SS wire were cross clamped and the laser

beam fired from the top. The cross section showed that top wire melted and wetted on the bottom wire. The joint

strength increased with laser power and peaked at 40N between 0.3-0.4 peak power of laser. The joining mechanism

showed in the schematic diagram.[1]

Figure 2 Laser braze welding of Pt to stainless steel[1]

Figure 3 shows the quartz glass joined by femtosecond laser. By utilizing the non-linear absorption of femtosecond

laser, the transparent quartz glass was directly welded without any interlayers. The cross section clearly showed the

weld seam width was around 30µm. The scanning electron microscopy image showed the fusion zone of the glass has

few defects. The maximum shear strength of the joined glass was around 40 MPa.

28

Figure 3 Femtosecond laser directly welding of quartz glass

Figure 4 shows the brazed Pt nanoparticles by Ag nano filler metal. The size of Ag nano particles was less than

10nm, which had the melting point in the range of 373-573K.[2] Therefore, the melting temperature of Ag was much

lower than that of Pt. The Ag nanoparticles was used as filler metal to braze Pt nano particles. The small radius fillets of

Ag nanoparticles indicates the Ag nanoparticles melted during laser radiation. It is believed that the Brownian motion is

important to the nano brazing process. The collision between nanoparticles induced the contacts of nanoparticles.

Figure 5 shows the morphology of joined nanowires. The selected area diffraction pattern on the nanowire indicated

the nanowire kept its original five twinned pentagonal structure. Our results indicated that femtosecond laser irradiation

can induce highly localized heat in nanowire, especially at the ends of nanowire and the crossed region.[3] Therefore,

the localized heat can melt the joined area and keep the rest of the nanowire stay its original shape and structure.

Figure 4 STEM image of nano brazed joint by femtosecond laser irradiation. The nano Ag cluster was the filler

metal and Pt-Ag nanoalloy was the base metal.[4]

Figure 5 Morphology of nanowires after femtosecond laser illumination indicating the location of plasmonic heating:

(a)-(c) on an amorphous carbon substrate, (d) after irradiation in liquid. In (a) melting occurs at the ends of the nanowire

and in the cross-sectional area adjacent to the junction between two wires. (b) and (c) show bright and dark field TEM

images of the terminal nano-particles, showing a grain boundary caused by melting and solidification. (d) after

29

irradiation in liquid without the presence of a substrate.[3]

4. Conclusions

CNT yarns, Pt micro wires, and quartz were successfully joined by laser micro joining. The configuration,

microstructures, joining mechanisms and joint strength were investigated and discussed. Nanojoining induced by

femtosecond laser was also performed and studied.

Acknowledgements

This work was supported by National Natural Science Foundation of China (Grant No. 51375261, 51075232), by

The Natural Science Foundation of Beijing ( Grant No. 3132020), by the Specialized Research Fund for Doctoral

Program of Higher Education (Grant No.20130002110009) and by Tsinghua University Initiative Scientific Research

Program (Grant No.2010THZ 02-1, 2013Z02-1).

References [1] Zou GS, Huang YD, Pequegnat A, Li XG, Khan MI and Zhou Y (2012) Crossed-Wire Laser Microwelding of Pt-10 Pct Ir

to 316 Low-Carbon Vacuum Mel ted Stainless Steel: Part I. Mechanism of Joint Formation. Metallurgical and Materials Transactions a-Physical

Metallurgy and Materials Science 43A(4): 1223-1233. [2] Hu A, Guo JY, Alarifi H, Patane G, Zhou Y, Compagnini G and Xu CX (2010) Low temperature sintering of Ag

nanoparticles for flexible electronics packaging. Applied Physics Letters 97(15): 153117-153117-3. [3] Liu L, Peng P, Hu A, Zou G, Duley W and Zhou YN (2013) Highly localized heat generation by femtosecond laser

induced plasmon excitation in Ag nanowires. Applied Physics Letters 102(7): 073107-073107-4. [4] Liu L, Huang H, Hu A, Zou G, Quintino L and Zhou Y (2013) Nano Brazing of Pt-Ag Nanoparticles under Femtosecond

Laser Irradiation. Nano-Micro Letters 5(2): 88-92.

30

Parallel Session B: Eco-welding & Manufacturing

31

In-situ Observation of Microstructural Evolution in Simulated Coarse-grained

HAZ of Bainitic Steel H. Terasaki

a, Y. Shintome

a, A. Takada

a and Y. Komizo

a

aJoining and Welding Research Institute, Osaka University

Abstract:

Microstructural evolution of the simulated coarse-grained HAZ of a bainitic steel was in-situ observed by

using the laser scanning confocal microscopy (LSCM). Hereafter, the thermal cycle applied is referred to as

‘‘CGHAZ-25 or 180,’’ as it takes 25 or 180 seconds to go from 800 C to 500 C in the cooling cycle. Granular

bainitic ferrite was formed along the thermal cycle of CGHAZ-180. On the other hand, upper bainite of the BII

and BIII type and martesite was formed in the case of CGHAZ-25. In this study, microstructural evolution was

discussed from viewpoint of grouping behavior of microstructural unit, in the case of CGHAZ25 and 180.

Furthermore, correlation between microstructural evolution and second phase formation such as cementite,

retained austenite and martensite-austenite (M-A) constituent was clarified by using scanning electron microscope

(SEM) and focused ion beam / transmission electron microscope (FIB/TEM) method.

Keywords: coarse grained heat-affected zone, bainitic steel, in-situ characterization

Fig.1 Snapshots of LSCM images during microstructural evolution of granular bainitic ferrite under the thermal cycle of

CGHAZ-180.

32

Welding and Joint Surface Nanocrystallization of

7A52 Aluminum Alloy

Furong Chen (College of Materials Science and Engineering Material Forming and Control Engineering Laboratory,

Inner Mongolia University of Technology, Hohhot 010051, China)

Abstract:

7A52 aluminum alloy is widely applied in many fields due to its high strength of weight ratio, specific

stiffness and its better corrosion resistance. However, strength reduction of weld seam, stress-corrosion cracking

of welded joint and other problems remain major challenges to its welding quality. To solve the above problems,

the paper makes the following tasks:（1）Optimize the parameters of Electron Beam Welding (EBW) and Tandem

MIG welding of 20mm 7A52 aluminum alloy and comparably analyze their joint performance.(2) Comparatively

analyze Monofilament MIG and Tandem MIG weld quality and joint performance of 40mm 7A52 aluminum alloy.

（3）The processes combined artificial aging and High Energy Shot Peening (HESP) technology and Ultrasonic

Impact Treatment (UIT) were carried out to achieve the joint Surface nanocrystallization and improve joint overall

performance of 20mm 7A52 aluminum alloy Tandem MIG welding. Obtain optimizing Surface

nanocrystallization parameters and compare the joint surface properties before and after Surface

nanocrystallization.

The test results show: (1) With the optimizing parameters of EBW and Tandem MIG, the EBW welded joint

has narrower HAZ, higher depth to width ratio, less inter porosities and finer grains. (2) Comparing the 7A52

aluminum alloy welded joint of Monofilament MIG with Tandem MIG, it shows that Tandem MIG welded joint

has better weld quality, smaller number and size of stomata and higher hardness values in joint regions. In

addition, its welding deformation is about 55% of Monofilament MIG welded joint. The tensile strength of

Monofilament MIG and Tandem MIG welded joint are respectively approximately 60% and 66% of the base

material and impact toughness are respectively about 63.7% and 74.2% of the base material. (3) The two

processes of artificial aging + HESP and UIT are all able to achieve joint Surface nanocrystallization and improve

overall performance of the joint.

Keyword: 7A52 aluminum alloy; EBW; Tandem MIG; Surface nanocrystallization

33

Effects of Martensite on Cold Cracking

in 600MPa Grade FCA Weld Metals

Myungjin Leea, Kyungmok Choa, Yongdeok Kimb, and Namhyun Kanga,*

aDept. of Materials Science and Engineering, Pusan National University, Busan 609-735, Korea bResearch and Development Center, Hyundai Welding Co., Ltd, Pohang 790-240, Korea

Abstract :

This study observed the cold crack susceptibility of three types of low-hydrogen flux-cored arc (FCA) weld

metals developed for a yield strength of 600 MPa. Cold cracks in the weld metal were measured using the

y-groove test, and four different preheating temperatures were employed from room temperature to 150 °C. The

microstructure of the y-groove weldment consisted of acicular ferrite, bainite, and martensite. All weld metals

showed cold cracking at room temperature, and a preheating temperature of 50 °C produced cold cracking only

for weld metal C, having the largest carbon equivalent and the largest volume fraction of bainite and martensite.

The volume expansion rate of the weld metals was measured when the austenite was transformed to martensite

during simulated weld cooling. Weld metal C showed the largest volume expansion rate (2.6%), resulting in the

largest probability of cold crack production. Moreover, the transformed martensite affected the cold crack

fractography in the weld metal. Intergranular fracture occurred in the region occupied by large volume fractions of

martensite and quasi-cleavage fracture was observed in regions of small volume fractions of martensite. The

difference of martensite volume fraction and fracture type was related to the localised Mn segregation in the FCA

welds: regions of high Mn content had significant martensite transformation and intergranular fracture.

Keywords : FCA welding, Cold cracking, Preheating, Martensite, Segregation

Fig. 1 Microstructure near the secondary cold crack for specimen C: (a) EBSD IQ image of the weld metal and

(b) the volume fraction of microstructure in the region of intergranular fracture and quasi-cleavage fracture.

*Corresponding author. Tel.: +82-51-5103027, Email address: nhkang@pusan.ac.kr (N. Kang)

34

Pinless Friction Stir Welding of Aluminum Alloy:

From Spot Weld to Butt and Lap Weld

Wenya Li *

State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, School of Materials

Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, Shaanxi, PR China

Abstract:

Pinless friction stir spot welding (P-FSSW) as a new variant of conventional FSSW has received increasing

attentions in recent years as it has successfully avoided the inherent keyhole in conventional FSSW joints.

However, as a relatively immature technology, there are many issues, e.g., how to avoid hook defect (HD), how to

enhance mechanical properties and if can be extended to other welds. A first priority for promoting the

applications of this technique is to overcome above problems. In this study, therefore, two specially designed

methods were applied to eliminate HD for superior joints. The one is changing welding parameters such as

rotating speed and dwell time. The other one is P-FSSW plus subsequent FSW (P-FSSW-FSW). Experimental

results showed that HD in P-FSSW joints cannot be eliminated by changing the welding parameters, but it is

successfully eliminated by using the P-FSSW-FSW process. The P-FSSW-FSW joints exhibited a tensile-shear

load of as much as 12kN. On the other hand, P-FSSW was extended to butt and lab welds, and this technique is

named as pinless friction stir welding (P-FSW). The preliminary experiments on P-FSW revealed that this process

can eliminates the lazy S presented in butted joint of conventional FSW, the maximum tensile strength of P-FSW

butted joints reaches to be about 326MPa. Moreover, in the P-FSW lapped joints the hook defect is observed,

resulting in very lower tensile-shear loads.

Keywords: Pinless friction stir spot welding; Pinless friction stir welding; 2024-T3 aluminum alloy; butt joint; Lap

joint; Tensile-shear strength

Corresponding author, Tel: ++86-29-88495226, Fax: ++86-29-88492642, E-mail: liwy@nwpu.edu.cn

35

36

Process Mechanism of Ultrasonic Vibration

Enhanced Friction Stir Welding

X.C. Liu, C.S. Wu* Institute of Materials Joining, Shandong University, Jinan 250061, China

Abstract：

The previous study has shown that ultrasonic vibration enhanced friction stir welding (FSW), a novel

modification of conventional FSW, can improve the weld formation quality, the welding efficiency, and the

mechanical properties of welded joints. In this study, the mechanism underlying ultrasonic vibration enhanced

FSW is experimentally investigated. The tool torque, traverse force and thermal cycles are measured during the

welding of 2A12-T4 aluminum alloys. The test data in ultrasonic vibration enhanced FSW are compared with

those in conventional FSW. The experimental results reveal that the tool torque decreases in ultrasonic vibration

enhanced FSW, but the variation of traverse force has different tendency as the welding conditions change. There

is almost no difference of the thermal cycles for two processes. It indicates that the exerted ultrasonic vibration

plays a role as the mechanical effect on the softened material around the tool pin, other than the thermal effect.

Through tool “sudden stop action” technique and “section” technique, the distribution of marker material on

the transverse cross-sections and the horizontal cross-sections with the tool exit hole after welding is observed and

analyzed, which provides a visual method to evaluate the material flow in FSW. The effect of ultrasonic vibration

on material flow in FSW can be revealed by the difference of material flow with and without ultrasonic energy.

The interaction of the ultrasonic energy with the plastically deformed materials in the vicinity of the tool pin

enhances the material flow and the strain rate so that quite a few advantages appear in ultrasonic vibration

enhanced FSW.

Corresponding author: wucs@sdu.edu.cn

37

Fatigue Life of the Repair TIG Welded Hastelloy X Superlloy

Sang-kyu Choi, Restu Sihotang, Sung-sang Park, and Eung-ryul Baek

School of Materials Science and Engineering,

Yeungnam Univ, Gyeongbuk 712-749, Republic of Korea

Abstract:

Hastelloy X in this study was applied in jet engine F-15 air fighter as shroud to isolate the engine from outer

skin. After 15 years operation the mechanical properties decreased gradually due to the precipitation of continues

second phases in the grain boundaries and precipitated inside the grain. Selective TEM analysis found that the

grain boundaries consist of M23C6 carbide, M6C carbide and small percentage of sigma (σ) phase. Furthermore,

it was confirmed the nano size of σ and miu (μ) phase inside the grain. The second phases reached 12 % volume

fraction in the structure after applying for 15 years in jet engine. Furthermore, the crack generally happen at the

edge of shroud due to the thermal and mechanical stress from jet engine operation to degraded shroud component.

Owing to the high cost of shroud, it is economically more viable to repair the crack by welding than to replace

them with a new part.

The high cycle fatigue number of the repair welded Hastelloy X superalloy on the used shroud part shows a much

lower compare to the as used shroud. In this study, it was investigated a microstructure examination of the degraded

shroud component and the heat affected zone (HAZ) of repair welded shroud. In the HAZ, the dissolution of the M23C6

carbides and smaller precipitates, the migration of the undissolved larger M23C6 carbide and M6C carbide, and the

liquation which due to simply melt of the segregated precipitates in the grain boundaries were frequently observed.

Interestingly, the segregated second phases which simply melt in the grain boundaries more easily happened at higher

heat input welding condition. High temperature tensile test was done in 3000C, 700

0C and 900

0C. It was obtained that

the toughness of welded sample is lower compare to the non-welded sample. One of the main reason to decrease the

tensile strength and the high cycle fatigue properties of the repair welded shroud is the formation of the liquid phase in

HAZ.

The solution heat treatment at 11700C for 5 minutes was suggested to obtain a better mechanical properties of the

used shroud part. The high cycle fatigue number at room temperature after solution heat treatment was almost double

compare to the before solution heat treatment sample under 420-500 MPa stress amplitude. However, the high cycle

fatigue number of repaire welded sample was shown a much lower compare to the used shroud and solution treated

shroud.

Key Words:Superalloy, Hastelloy X, Grain boundary liquation, High cycle fatigue test.

Corresponding Author: Tel: +82-53-810-2473, Fax: +82-53-810-4628

Email address: erbaek@ynu.ac.kr

38

Investigation on Friction Hydro-pillar Processing by Experiments and

Numerical Simulation

L.Y. Xu1,2*

, Y.C. Xu1,2

, H.Y. Jing1,2

, Y.D. Han1,2

, 1 School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China

2 Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300072, China

E-mail address: xulianyong@tju.edu.cn

Abstract:

This paper focuses on the effects of geometry containing rod and hole configurations, welding parameters

including rotational speed and applied downward force on weld defects, temperature response, stress evolution in

friction hydro-pillar processing (FHPP). Various configurations of the rod and hole are designed and all welds are

performed by using a self-developed high-performance platform with the same welding parameters. The

experimental results indicate that the defects usually appear at the bottom of the hole, but the upper region bonds

well. The quality of welded joints is deeply affected by the bottom filling which is called initial stage. Therefore,

the finite-element method (FEM) is employed to simulate the initial stage of FHPP. The simulated results agree

well with those of the experiments. The results indicate that the geometry of the hole influences the welding

quality more strongly than the shape of the rod and that weld samples with a rounded corner at the bottom of the

hole bond well. Moreover, different shapes of the rods cause different stress states and temperature distributions,

which also influence the quality of welded joints. The simulation results for various welding parameters showed

that with increasing rotational speed and applied downward force, the rate of temperature rise increases.

Consequently, significant axial shortening and fast-formed flash occur earlier. Further, stress gradually decreases

with rising temperature.

Keywords: FHPP, Numerical simulation, Configurations, Welding parameters, Defects, Temperature distribution,

39

40

Parallel Session C: Welding Behavior & Joint Properties

41

Hierarchical Damage Simulation for Structural Performance-Based Material

Design

Mitsuru Ohataa,*

a Division of Materials and Manufacturing Science, Graduate School of Engineering,

Osaka University, 2-1 Yamada-Oka, Suita, Osaka 565-0871, JAPAN

Abstract:

Hierarchical approach to link the micro-structural characteristics of a material and a ductile crack

growth resistance curve of a component is proposed. First attention is paid to reveal mechanical properties

that control ductile crack growth resistance curve (CTOD-R curve), so that the R-curve could be numerically

predicted only from those properties. It is shown from the observation of a mechanism for ductile crack

growth that two types of “ductile properties” of steel associated with ductile damage can mainly influence

CTOD-R curve; one is a resistance of ductile crack initiation estimated with critical local strain for ductile

cracking from the surface of notch root, and the other one is a stress triaxiality dependent ductility obtained

with circumferentially notched round-bar specimens. The damage model for numerically simulating the

R-curve is proposed taking these two “ductile properties” into account, where ductile crack initiation from

crack-tip is in accordance with local strain criterion, and subsequent crack growth triaxiality dependent

damage criterion. This macroscopic simulation can correlate the mechanical properties of steel with

CTOD-R curve of a component. The second approach is to develop a simulation method to predict the

effect of micro-structural characteristics of a multi-phase material on the two types of ductile properties that

were found to be ductile crack growth controlling mechanical properties. To simulate meso-scale ductile

damage behaviors, 3D micro-structural FE-model is developed for analyzing the stress/strain localization

behaviors by micro-structural strength mismatch and ductile damage model for reproducing damage

evolution up to micro-void/micro-crack formation. This meso-scopic simulation can correlate

micro-structural characteristics with mechanical properties of two-phase steel. Through the proposed

hierarchical approaches, micro-structural morphology of a multi-phase material to improve a ductile crack

growth resistance of a component can be discussed.

Keywords Damage model; 3D-simulation; Microstructure; Ductile crack growth resistance

Fig. 1. Concept for developing hierarchical simulation method.

Corresponding author. Tel.: +81-6-6879-7545, Fax: +81-6-6879-7545

Email address : ohata@mapse.eng.osaka-u.ac.jp

42

Three-dimensional Porosity-induced Fatigue Cracking in Hybrid Laser

Welded Al Alloys via High-resolution SR-μCT

S.C. Wua,*, C. Yu

a, W.H. Zhang

a, J.Y. Buffiere

b, Y.N. Fu

c

aState Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, China bUniversité de Lyon, INSA-Lyon, MATEIS CNRS UMR 5510, 69621 Villeurbanne, France

cShanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Shanghai 201204, China

Abstract:

As near-spherical hydrogen pores seriously destroy the integrity of hybrid laser-arc-welded 7075-T6 Al

structures, it is essential to evaluate their effect on fatigue crack initiation and propagation for a fitness-for-service

welded joint. The interaction between the pores and fatigue cracks is characterized in situ via high-resolution

synchrotron radiation X-ray microcomputed tomography. The spatial distribution and growth behavior of the

pores are then investigated and quantified. Gas porosity inside 7075-T6 hybrid welds is found to play a significant

role in the fatigue crack nucleation and propagation process. The volume fraction and total number of pores

increase slightly with increasing number of fatigue cycles, which provides a key indicator for the damage

evolution. Meanwhile, surface-based optical microscopy, scanning electron microscopy, and post-mortem

fractography are also employed to analyze the mechanism of fatigue crack initiation and propagation.

Experimental results show that the micropores grow and distort during fatigue cyclic loading, resulting in fatigue

cracks. Owing to the difference in misorientations of adjacent grains and discrete pores together with matured

secondary cracks, fatigue cracks exhibit intricate three-dimensional morphological features. It is also found that in

the fatigue loads, the maximum micropore is not a favorable site, in terms of physical suitability, for fatigue crack

initiation and propagation, and the diameter of porosity-induced cracks is roughly 10–150 μm.

Keywords: Gas porosity; Fatigue cracks; X-ray computed tomography; Al alloy; Hybrid welding

Fig. 1. Interaction between the pores and fatigue cracks inside hybrid-welded 7075-T6 joints (Weld-2). The

number of fatigue cycles were (a) N = 300031 and (b) N = 410778.

*Corresponding author. Tel.: +86-28-87634788, Fax: +86-28-87600868.

Email address: wusc@swjtu.cn (S.C. Wu).

43

Reviews on Nucleation Mechanisms of Acicular Ferrite

in Steel Welds

Kangmyung Seo*, Young-min Kim**, Hee Jin Kim**, Changhee Lee*

* Hanyang Univeristy, Korea

**Korea Institute of Industrial Technology (KITECH), Korea

Abstract: Acicular ferrite (AF) is a microstructure that nucleates from non-metallic inclusions in ferritic welds and

grows in radial directions. However, not all inclusions act as nucleation sites but a certain type of inclusions such

as Ti-containing ones is known to be effective for nucleation. In order to explain such a difference, several

suggestions have been proposed with or without experimental evidences. This paper presents the effectiveness of

the previously proposed three mechanisms based on the experimental results recently obtained.

A. Simple Heterogeneous Nucleation

Based on calculation results of the free energy barrier to ferrite nucleation using classical heterogeneous

nucleation theory, it was considered that the energy barrier for ferrite nucleation decreases with the increase in

inclusion size. Accordingly, if this mechanism operates then larger inclusions more likely to nucleate AF than

smaller ones and there are some evidences for this.

However, recent results show that the extent of the effect of inclusion size on AF nucleation probability is

greatly different depending on the inclusion characteristics that can be explained by the following two

mechanisms.

B. Good Lattice Matching

This hypothesis suggests that several specific phases that have good lattice misfit with ferrite are responsible

for nucleating acicular ferrite. There is plenty of evidence for this mechanism. For example, MnAl2O4, TiN and

TiO are all appear to be effective for nucleating AF in steel weld metals by this mechanism as those phases are

low in misfit with ferrite, less than 4.0%. Recently, MnTi2O4 was found to be effective even though it has a misfit

value as high as 6%.

C. Formation of MDZ

In Ti-containing steels, it was often observed that manganese can diffuse into inclusions and it results in

Mn-depleted zone (MDZ) in the surrounding steel matrix especially when the inclusions are predominant

withTi2O3 phase. As MDZ can increase the thermodynamic driving force for ferrite transformation, MDZ

formation becomes the most favorable one for AF nucleation in heat-treated steels. However, welding researchers

have not been favor to this mechanism largely due to the lack of diffusion time available during weld thermal

cycle and partly due to the absence of experimental evidences. However, the MDZ formation were recently

observed in two different weld systems, It was also found that these MDZ are always accompanying with the

ilmenite inclusions, mixture of Ti2O3 and MnTiO3..

Therefore, no single mechanism can explain AF nucleation on inclusions in weld metals. Of those three

mechanisms described above, the first mechanism applies to all the inclusions but to a different extent because

one of the latter two can be added depending on the inclusion characteristics. It implies that alloy design for

welding consumables with improved toughness now needs to focus on ‘how to design the inclusions more

effective for acicular ferrite nucleation, i.e. inclusion-design’.

44

45

Application of Narrow-Gap Welding Technology of Turbine Welded Rotor

Xia Liu1, Fenggui Lu

2

1. Shanghai Turbine Plant of Shanghai Electric Power Generation Equipment, Shanghai 200240, China

2. School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

Abstract:

Due to the difficulties to manufacture large forgings in making rotors with heavy section, it is necessary to

combine rotor via proper welding technology to meet the demand. In this report, the history of welded rotor with

narrow-gap welding technology (NG-SAW or NG-TIG) is introduced to show that lots of successful experiences

in putting welded rotor into applications. And with the increase of steam parameters, 620℃ level steam turbine is

put forward, which leads to the welding of dissimilar steels rotor become a big challenge. The design and

background of 620℃ welded rotor will be described detailedly. In the long-term operation at elevated

temperatures of steam turbine components, properties such as fatigue, creep must be taken into account. The

properties of welded joint could meet the requirements of design based on the test results, which will provide

reliable data in service. And finally, the pilot study of 700℃ welded rotor is involved.

46

Interfacial Oxidation of Aluminum at Liquid Alloy/Sapphire Interfaces under

Ultrasonic Filed and Its Application in Joining

Yan Jiuchun, Cui Wei

State Key Laboratory of Advanced Welding and Joining,

Harbin Institute of Technology, Harbin 150001, People’s Republic of China

Abstract:

Wetting and bonding at the metal/ceramic interface is a core issue in joining ceramics. Sapphire

(monocrystalline α-Al2O3) is a typical oxide ceramic. Wetting of liquid metals on sapphire is usually very

difficult because of the very inert chemical properties of sapphire. Here we report a novel joining method through

the ultrasonic interfacial oxidation of aluminum at the interface between liquid alloys and sapphire. This reaction

significantly promotes the wetting and bonding at the alloy/sapphire interface. Several novel brazing methods

have been developed based on these phenomena. Sn-Zn-Al, Sn-Ag-Cu-Al, and Sn-Bi-Al alloys were used to join

sapphire at ~200 ºC, the shear strength was 30-50MPa. The strength of the joints is very high comparing to that

joined by traditional methods. Thus, we proposed a novel technical route to make ceramic joints at lower

temperature.

47

48

Prediction of Proper Arc Welding Condition by

Artificial Neural Network for Automotive Industry

Jungho Cho*,a

, Seung-Hwan Bae*, Jung-Jae Lee

*, Jong-Won Yoon

*School of Mechanical Engineering, Chungbuk National University, Cheongju 361-763, Korea

**Dept. of Advanced Materials Engineering, Dong-Eui University, Pusan 614-714, Korea

Abstract:

Steel sheets for automobiles are becoming diverse due to the requirements of strict safety regulation and

higher fuel efficiency. Accordingly, the number of combinations for arc welding of steel sheet is exponentially

increased in these days. Therefore conducting the whole welding experiments for the purpose of deriving proper

process window for various steel sheet combinations is almost impossible. So this study adopted artificial neural

network (ANN) to complete the process window derivation work by training the network and predicting proper

welding conditions for steel combinations omitted in experiment. First of all, types of ANN and proper system

variables were decided by simple test by comparing experiment and prediction. Then the ANN is trained by

experimental result. The prediction accuracy of trained ANN is also evaluated through comparison a set of

experiment and prediction result.

Key Words : Automotive, Artificial Neural Network, Arc Welding, GMAW

a Corresponding: junghocho@cbnu.ac.kr, +82-43-261-2445

49

Microstructure and Mechanical Properties of Dissimilar Joints of Ti-Al

Intermetallics with Ni-based Wrought Superalloy

Hua-Ping Xiong*, Bing-Qing Chen, Lei Ye, Bo Chen

Laboratory of Welding and Forging, Beijing Institute of Aeronautical Materials, 100095 Beijing, P. R. China

Abstract :

In general, it is extremely difficult to join Ti-Al system intermetallics and Ni-based superalloys because of

their great differences in chemical compositions and thermo-mechanical properties. But the dissimilar joining of

the two kinds of materials is rather attractive for high-temperature application in advanced aeroengines.

In this study, dissimilar joining of Ti3Al-based alloy to Ni-based superalloy (Inconel 718) was carried out

using gas tungsten arc (GTA) welding technology with Ti-Nb and Ti-Ni-Nb filler alloys. The average

room-temperature tensile strength of the joint welded with Ti-Nb was 202 MPa and the strength value of the one

welded with Ti-Ni-Nb was 128 MPa. For both fillers, the weak links of the dissimilar joints were the weld/In718

interfaces. The presence of TiNi, TiNi3 and Ni3Nb intermetallic compounds in the joint welded with Ti-Ni-Nb

induced microcracks at the weld/In718 interface and deteriorated the mechanical properties of the joint.

In the meantime, dissimilar welding of a Ti3Al-based alloy and the Ni-based superalloy was successfully

carried out by using a Ni-Cu alloy as filler material. It is found that the weld/Ti3Al interface is composed of

Ti2AlNb matrix dissolved with Ni and Cu, Al(Cu, Ni)2Ti, (Cu, Ni)2Ti, (Nb, Ti) solid solution, and so on. The weld

and In718/weld interface mainly consist of (Cu, Ni) solid solutions. The average room-temperature tensile

strength of the joints reaches 242 MPa and up to 73.6% of the value can be maintained at 600oC. The brittle

intermetallic phase of Ti2AlNb matrix dissolved with Ni and Cu at the weld/Ti3Al interface is the weak link of the

joint.

Additionally, TiZr-based and CoFeNiCr-based brazing filler metals were also designed for the joining of TiAl

intermetallics to GH536 superalloy. Firstly the wettability of the filler alloys was studied with the sessile drop

method. Then the filler alloys were fabricated into filler foils by a rapidly-solidifying technique, and they were

used in the subsequent brazing experiment. The results showed that the shear strength of the joints brazed with the

TiZr-based filler foils was 200 MPa at room temperature, and the joint strength at 760oC for the CoFeNiCr-based

filler alloy even reached 286 MPa.

It is pointed out that, development of new high-temperature-tolerance welding consumables or brazing alloys,

joining of dissimilar materials, and study on joint assessment and engineering application would be the important

research areas in future.

Keywords: Ti3Al-based alloy; TiAl; Ni-based superalloy; welding; microstructure; mechanical properties.

Corresponding author: Hua-ping Xiong. Tel.: +86-10-6249-6680. Fax: +86-10-6245-6925.

E-mail address: heaping.xiong@biam.ac.cn; xionghuaping69@sina.cn

50

An Investigation of Liquid Metal Embrittlement in Resistance Spot Welding of

High Manganese TWIP Steels

Y.D. Parka,*, M. A Haque

a, C.W. Ji

b, K.G. Chin

c, I.S. Woo

c

aDong-Eui University, Department of Advanced Materials Engineering, Busan, 614-714, Korea

bSchool of Materials Science and Engineering, Pusan National University, Busan, Korea

cposco Technical Research Laboratories, Gwangyang, Korea

Abstract:

Recently the automobile manufacturers are particularly interested in High manganese austenitic TWinning

Induced Plasticity (TWIP) steels due to their outstanding mechanical properties at room temperature combining

high strength (900 MPa) and ductility(60% elongation) based on the high work-hardening capability. The ductility

is the main difference between the TWIP steels and other Advance High Strength Steels (AHSS). The austenitic

microstructure of TWIP steels along with the galvanized (GI) coating are prone to Liquid Metal Embrittlement

(LME) during Resistance Spot Welding (RSW). There are many models to explain the LME mechanism. But the

LME phenomena is still not fully understood yet. In this frame work, coating layer melting behavior, LME

initialization and propagation in galvanized TWIP (GI TWIP) steel have been observed with respect to the

welding time during RSW by a high speed camera and monitoring system. The results obtained (by half electrode)

from the high speed camera have been also compared with full electrode RSW. The experimental results revealed

that coating layer melted in the electrode-sheet interface even during the holding time and squeezed out molten Zn

accumulated at the outside of the electrode imprint. Due to high temperature in the outside of the electrode imprint,

coating layer of that area melted as well as stagnant and this molten Zn ensured a rich supply of liquid during the

LME propagation. First LME initiated in the inside electrode imprint and LME propagation was stopped when the

electrode came in close contact with the sheet and impeded the supply of liquid Zn. The maximum LME started in

the outside of the electrode imprint where there was no contact between the electrode and workpiece and crack

continued to propagate even during the holding time. Finally temperature distribution, nugget growth and stress

analysis with welding time have been evaluated by the simulation and simulated results strongly supported the

LME formation during the high speed camera operation.

Keywords: TWIP steel; Liquid metal embrittlement; Zn Coating; Resistance Spot Welding; Nugget Growth

Fig. 1. LME observed in flat area of inside electrode imprint at after expulsion current (10kA); Maximum

temperature by full electrode welding conditions in curved area at the welding time of (a) 68ms (b) 136ms (c)

204ms (d) 340ms

*Corresponding author. Tel.: +82-51-8902290, Email address: ypark@deu.ac.kr (Y.D. Park).

827 C

(a)

1159 C

(b)

1017 C

(d)

36 C(c)

51

Parallel Session D Advanced Arc Welding Physics

52

List of Attendants

53

Influence Mechanism of Process Parameters on Keyhole-induced Porosity

Formation Based on 3D Transient Modelling

Fenggui Lu, Zhuguo Li, Xibin Li, Xinhua Tang, Yixiong Wu

Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and

Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

Abstract:

Keyhole-induced porosity occurring in laser weld with deep-penetration becomes a big issue in laser

manufacturing the components with heavy section. In order to better insight into the keyhole-induced porosity

formation process and its influencing factors, a there dimension (3D) transient model is proposed to investigate

the correlations between keyhole and porosity at different process parameters. Fluid flow, bubble movement and

solidification are coupling considered in this model. Results indicate that the number of bubbles is mainly

determined by keyhole stability. The keyhole easily tends to close and collapse during laser welding as increasing

laser power, decreasing velocity and beam diameter, which contribute to violent flow, strong evaporation of

molten pool negatively acting on the keyhole with large ratio of depth to width. However, the evolution efficiency

from bubbles to porosities depends on solidification rate and temperature gradient, most of bubbles adjacent to

fusion line transfer into porosities due to high solidification rate. A good agreement is obtained between the

simulations and experiments.

Keywords: keyhole-induced porosity; process parameters; evolution efficiency

Figure Porosities variation with laser beam size: (a) D=0.6mm, (b) D=0.9mm

54

Theoretical Analysis of Variable Polarity Arc Welding of Aluminum

Jungho Cho*,a

, Jung-Jae Lee*, Seung-Hwan Bae

*

*School of Mechanical Engineering, Chungbuk National University, Cheongju 361-763, Korea

Abstract:

Due to increasing demand for the aluminum material to the light-weight requirements of the various

transportations, the interest of the aluminum welding technique is also growing. However, the aluminum oxide

has significantly greater melting temperature and hardness than pure aluminum therefore these are inferred as

main reasons of low arc weldability. In this study, variable polarity GTA is applied to lap joint fillet welding of

5052 aluminum alloy plates of 3mm thickness. Result of weldment itself was quite successful but the main issue

was focused on the effect of DCEP duty ratio on bead formation because it is resulted as exactly opposite to

conventional arc theory. Conventional arc theories about anode heating and cleaning effect were not applicable to

explain the strange result. Therefore an alternative physical theory is suggested through the study and it is

combination of tunneling effect and random walk of cathode spot. Suggested idea successfully explained the

abnormal result and it also explained previously reported unaccountable result about relationship between oxide

thickness and heat input in variable polarity GTA of aluminum welding.

Key Words : Aluminum, Variable Polarity, TIG, GTAW, Tunneling Effect

Corresponding: junghocho@cbnu.ac.kr, +82-43-261-2445

Figure 1. Cross sectional bead shape for various arc current and DCEP duty ratio.

55

56

Comprehensive Simulation of Laser Cladding Process

of a Nickel-based Superalloy

Pulin Nie*, Zhuguo Li, Jian Huang

Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, PR China

Abstract:

The laser cladding process is a highly non-linear problem that couples the phenomenon of fluid, heat transfer

and metallurgical transformation. In order to simulate such a complex process, a comprehensive numerical

model which combines the computational fluid dynamics (CFD), a physical energy function, the finite element

method (FEM) and the stochastic analysis is developed and applied to a Nickel-based superalloy laser cladding

process. The trajectory of the powder stream during the feeding procedure, the formation of the deposited

coating on the substrate, the thermal history experienced by the flying powder particles, deposited coating and

substrate, and the evolution of the microstructure in the deposited coating are investigated by this comprehensive

simulation from macro- to micro- scales. The simulation results show that the solidified microstructure of the

deposited coating is possible to be controlled by solidification conditions via optimizing the processing parameters

of laser cladding. This work contributes to the comprehensive understanding of laser cladding, as well as

provides a fundamental basis for controlling the microstructure in laser cladding nickel-based superalloy coatings.

Keywords: Laser cladding; Nickel-based superalloy; Simulation

_______________________

Contacts: Corresponding author: Pulin Nie E-mail: nplhxy@sjtu.edu.cn Tel: +86-21-54748940-8022 Fax:+86-21-34203024

57

Effects of Profile Force on Ductility of UHSS Resistance Weld Joint (Part 1)

Kyo Eun Lee*, Han Jun Lin*, Sun Hee Choi*, Tae Min Kim*, Hee Seok Chang** , Duyoul Choi***

* Student, Dept. of Mechanical Engineering, Myongji University, Yong-Inn city,449-728, Rep. of Korea

** Professor, Dept. of Mechanical Engineering, Myongji University, Yong-Inn city,449-728, Rep. of Korea

*** Principal Researcher, POSCO Global R&D Center, Songdo-dong, Incheon 406-840, Rep. of Korea

Abstract:

Recent application of Ultra high strength steel (UHSS) to vehicle body manufacturing has become an

important issue. Despite decrease in total weight of car body, UHSS-intensive vehicle shows improved crash

performance. Since resistance spot welding (RSW) has been conventional tool of joining UHSS sheet for

automotive assemblies, many researches have focused on weldability of UHSS in view of heat schedule.

In general, weldability is determined by carbon content of carbon steel and usually deteriorated as the amount of

carbon increases. The hardened weld zone of high-carbon steel shows more fragile than that of low carbon steel.

In this case, pre-heat or post-weld heat treatment process may improve ductility.

This paper investigated effects of profile hold force on tensile-shear strength of UHSS weld specimen. In

comparison to conventional constant hold force during RSW processes, profile force (step increase of hold force)

is applied through servo force control system. The effect of step increase on the tensile-shear strength is

experimentally investigated.

According to the experimental results, major finding is that ductility of weld zone is remarkably increased with

step increase of hold force. Numerous researches have tried various pre/post heat treatments to obtain ductile

UHSS weld specimen. Few results have reported to be successful and practical. This is promising result in that

application of profile hold force is new method for ductile UHSS weld specimen.

Key Words:servo force control, profile force, UHSS, tensile-shear strength, Resistance Spot Welding

58

59

A Deeply Description of Welding Plasma Arc – the Separability and

Measurement of Arc components S.J. Chen, F. Jiang

S.J. Chen (sjchen@bjut.edu.cn) and F. Jiang are with the Welding Research Institute, Beijing University of Technology, China.

Abstract:

In normal welding conditions, the arc plasma and electron flow are merged forming an arc of classical

definition. To better understand keyhole plasma arc and help improve the process, the authors consider a welding

arc as a composite of an electron flow and electrically neutral arc plasma consisting of equal numbers of ions and

electrons. the arc plasma and the electron flow which ionized the gas to form the arc plasma are considered

separable. To demonstrate the arc separation phenomena, this initial study deviates the anode from the tungsten

axis both for the constrained plasma arc (PA) and unconstrained free gas tungsten arc (GTA) to deviate the

electron flow. The observed phenomena are qualitatively analyzed to show that the separability is indeed a

property of the welding arc. This phenomenon provides a better way to understand the arc fundamentally. Hence,

this work designed an innovative experimental system to measure/record the heat and pressure from the separated

arc components – arc plasma and electron flow. An algorithm was proposed to calculate/derive the distribution of

the pressure from its bulk measurements that are easy to obtain accurately. Experiments were conducted to study

the effects of welding parameters on the heat and pressure in the arc components. It is found that for the

constrained plasma arc (PA), the heat applied into the work-piece through the arc plasma exceeds that from the

electron flow and this dominance increases as the current increases. However, for the heat from the electron flow,

the constraint on the arc does not change it significantly as can be seen from the comparison with that in free GTA

(gas tungsten arc). For the pressure in PA, the arc plasma plays the dominant role in determining its amplitude,

while the electron flow only primarily contributes to the distribution.

60

Time-resolved X-ray Study of Thermodynamic Non-equilibrium

in Weld Solidification

H. Terasakia and Y. Komizo

a

aJoining and Welding Research Institute, Osaka University

Abstract:

It is well-known that solidification and solid-state phase transformation during welding process is in

thermodynamic non-equilibrium state. It is due to characteristic thermal cycle of welding, that is, rapid heating

and cooling. Quantitative understanding of non-equilibrium state is important to control the microstructure of

weld.

From late 1990’s, bright X-ray generated in synchrotron radiation source has been used to track the

microstructural change under the thermal cycle of welding. However, the literature contains few studies on the

quantitative analysis about the thermodynamic non-equilibrium during welding process.

In the present study, in order to provide the quantitative discussion about thermodynamic non-equilibrium state

during welding process, a bright X-ray is used to track phase transition between the liquid, delta-ferrite and

austenite phase during GTA welding process. Furthermore, measured diffraction data is corresponded to the

temperature at the centerline of the weld bead. An area detector with highly S/N ratio is used to detect the phase

transition of liquid phase under the welding thermal cycle. Furthermore, a radiation thermometer (RT) with

immersion-type optical fiber is used to measure the temperature at the centerline of the weld bead within the

irradiated area.

Keywords: Solidification, thermodynamic non-equilibrium, Time-resolved X-ray diffraction analysis

Fig. 1 D-spacing and temperature during solidification process of Cr-Ni steel in TIG welding.

61

Porosity control in wire plus arc additive manufacturing (WAAM) of

aluminium-copper alloy Dr. Baoqiang CONG

School of Mechanical Engineering and Automation, Beihang University, 100191, China

Abstract:

High strength aluminium alloys have gathered wide acceptance in aeronautic and aerospace applications due

to their excellent strength, fracture properties and good corrosion resistance. The conventional method of

manufacturing aluminium alloy components is using subtractive processes which machine the component out of a

solid alloy block. Most of aluminium alloy needs to be machined away which results in a long production time

and high cost. In addition it cannot satisfy the requirement for sustainability of modern industry. Thus, more

attention has been focused on the metal additive manufacturing (AM), which has proved to be an economic

alternative method for fabricating metal components. Among different AM processes, wire plus arc additive

manufacturing (WAAM) is becoming more popular due to its advantages in high deposition rate, low production

cost, perfect density, materials-saving and the capability for fabricating large-scale components.

The cold metal transfer (CMT) process is a relatively new technique which is characterised by its low heat

input, low spatter and high deposition rate. It has been observed that this process exhibits greater control of

droplet transfer and dilution. Recently CMT has been developed into different droplet transfer modes which are

conventional CMT, CMT pulse (CMT-P), CMT advanced (CMT-ADV) and CMT pulse advanced (CMT-PADV).

Due to the excellent characteristics in terms of low spatter and automatic adjustment of contact tip to work

distance the CMT process is a potential process to be used in the AM application of aluminium alloy.

In this study, the effect of CMT process variants on the porosity characteristic of additive manufactured

Al-6.3%Cu alloy has been systematically investigated. Experiments were performed on both single layer deposits

and multilayer deposits. It was found that deposit porosity is significantly influenced by the CMT process.

Conventional CMT is not suitable for the additive manufacturing process because it produces a large amount of

gas pores, even in single layer deposit. CMT-PADV proved to be the most suitable process for depositing

aluminium alloy due to its excellent performance in controlling porosity. With correct parameter setting the gas

pores can be eliminated. It was found that the key factors that enable the CMT-PADV process to control the

porosity efficiently are the low heat input, a fine equiaxed grain structure and effective oxide cleaning of the wire.

Acknowledgements:

The researcher would like to thank all the technician members in Welding Engineering and Laser Processing

Centre in Cranfield University. The work was supported by the WAAMat programme.

62

List of Attendants

63

4th EAST-WJ List of Attendants

Name Title Affiliation Address Representing

Society E-Mail

Sook-Hwan Kim

Researcher (Dr.)

RIST 67 CheongAm-Ro, Nam-Gu , Pohang, 790330,

Korea KWJS weldksh@rist.re.kr

Hee Jin Kim Senior

researcher KITECH

Yangdaegiro-gil 89, Ipjang-myun, Seobuk-gu, Chonan-si, 331815, Korea

KWJS kimhj@kitech.re.kr

Dae-up Kim Dr. KITECH Palbokdong , Deokjin-gu, Jeonju-si,

Jeollabuk-do, 561-739,Korea KWJS dukim@kitech.re.kr

Yeong Do Park Professor DONG-EUI University

176 Eomgwangro, Busanjin-gu, Busan, 614714,Korea

KWJS ypark@deu.ac.kr

Jongwon Yoon Professor DONG-EUI University

San 24, Gayadong, Busanjingu, Busan, 614714, Korea

KWJS jwyoon@deu.ac.kr

Eung-ryul Baek Professor Yeungnam University

280 Daehak-ro, Gyeongsan,712749, Korea KWJS erbaek@yu.ac.kr

Sehun Rhee Professor Hanyang University

17 Haengdang-dong, Seongdong-gu, Seoul,133791, Korea

KWJS srhee@hanyang.ac.kr

Hee Seok Chang

Professor Myongji University

Department of Mechanical Engineering, San

38-2, Nam-dong , Yong-Inn city, Kyung-ki do，

449-728，Korea

KWJS hschang@mju.ac.kr

Seung-Boo Jung

Professor Sungkyunkwan

University 2066, SEOBU-RO, JANGAN-GU, SUWON-SI,

GYEONG GI-DO,440746, Korea KWJS sbjung@skku.edu

Jae Pil Jung Professor University of Seoul 90 JunNong-dong, DongDaeMun-gu, Seoul ,

130743, Korea KWJS jpjung@uos.ac.kr

Nam Hyun Kang

Professor Pusan National

University

2 Pusan University-Ro 63th-Gil, Geumjeong-Gu，

Busan，609-735,Korea KWJS nhkang@pusan.ac.kr

Jungho Cho Professor Chungbuk National

University

52 Naesudong-ro, Seowon-gu ,Cheongju, Chungbuk, 361763,Rep of Korea

KWJS junghocho@chungbuk.ac.kr

Jungjae Lee Mr. Chungbuk National

University

52 Naesudong-ro, Seowon-gu ,Cheongju, Chungbuk, 361763,Rep of Korea

KWJS theuglyman@nate.com

64

Seunghwan Bae

Mr. Chungbuk National

University

52 Naesudong-ro, Seowon-gu ,Cheongju, Chungbuk, 361763,Rep of Korea

KWJS nghwan1@nate.com

Yoshinori Hirata

Professor Osaka University 2-1,Yamadaoka, Suita-shi,

Osaka,565-0871,Japan JWS hirata@mapse.eng.osaka-u.ac.jp

Qiaofeng Zhou Mr. Osaka University 2-1,Yamadaoka, Suita-shi,

Osaka,565-0871,Japan JWS q-zhou@mit.eng.osaka-u.ac.jp

Fumikazu Miyasaka

Associate Professor

Osaka University 2-1,Yamadaoka, Suita-shi,

Osaka,565-0871,Japan JWS miyasaka@ams.eng.osaka-u.ac.jp

Mitsuru Ohata Associate Professor

Osaka University 2-1,Yamadaoka, Suita-shi,

Osaka,565-0871,Japan JWS ohata@mapse.eng.osaka-u.ac.jp

Kazuya Ishida Mr. Osaka University 11-1 Mihogaoka, Ibaraki, Osaka 576-0047,

Japan JWS k.ishida@jwri.osaka-u.ac.jp

Manabu Tanaka

Professor Osaka University 11-1 Mihogaoka, Ibaraki, Osaka 576-0047,

Japan JWS tanaka@jwri.osaka-u.ac.jp

Hidenori Terasaki

Associate Professor

Osaka University 11-1 Mihogaoka, Ibaraki, Osaka 576-0047,

Japan JWS hidenori@jwri.osaka-u.ac.jp

Yasuo Takahashi

Professor Osaka University 11-1 Mihogaoka, Ibaraki, Osaka 576-0047,

Japan JWS takasy@casi.osaka-u.ac.jp

Mikihito Hirohata

Assistant Professor

Nagoya University Furo-cho, Chikusa-ku, Nagoya, 4648603, Japan JWS hirohata@civil.nagoya-u.ac.jp

Kenji Shinozaki Professor Hiroshima University

1-4-1 Kagamiyama,Higashi-Hiroshima, 739-8527,Japan

JWS kshino@hiroshima-u.ac.jp

Kota Kadoi Assistant Professor

Hiroshima University

1-4-1 Kagamiyama,Higashi-Hiroshima, 739-8527,Japan

JWS kadoi@hiroshima-u.ac.jp

Takanori Kitamura

Assistant Professor

Kyushu Institute of Technology

Kitakyushu,804-8550,Japan JWS kitamura.takanori599@

mail.kyutech.jp

Hiroyuki Kokawa

Professor Tohoku University

Department of Materials Processing, 6-6-02

Aramaki-aza-Aoba, Aoba-ku，Sendai，980-8579,

Japan

JWS kokawa@material.tohoku.ac.jp

Shoichi Matsuda

Associate Professor

University of the Ryukyus

1 Senbaru, Nishihara ,903-0213, Japan JWS matsudas@tec.u-ryukyu.ac.jp

65

Changjiu Li Professor Xi'an Jiaotong

University 28 west Xianning Rd., Xi'an , 710049,China CWS licj@mail.xjtu.edu.cn

Jianxun Zhang Professor Xi'an Jiaotong

University 28 west Xianning Rd., Xi'an , 710049,China CWS jxzhang@mail.xjtu.edu.cn

Guifeng Zhang Professor Xi'an Jiaotong

University 28 west Xianning Rd., Xi'an , 710049,China JWS gfzhang@mail.xjtu.edu.cn

Yixiong Wu Professor Shanghai Jiaotong

University 800 Dongchuan Road, Minhang District,Shanghai 200240, China

CWS yxwu@sjtu.edu.cn

Fenggui Lu Associate Professor

Shanghai Jiaotong University

800 Dongchuan Road, Minhang District,Shanghai 200240, China

CWS Lfg119@sjtu.edu.cn

Chun Yu Lecturer Shanghai Jiaotong

University 800 Dongchuan Road, Minhang District,Shanghai 200240, China

CWS yuchun1980@sjtu.edu.cn

Pulin Nie Lecturer Shanghai Jiaotong

University 800 Dongchuan Road, Minhang District,Shanghai 200240, China

CWS nplhxy@sjtu.edu.cn

Jiuchun Yan Professor Harbin Institute of

Technology No 92, Xidazhi street, Harbin 150001, China CWS jcyan@hit.edu.cn

Yanhong Tian Professor Harbin Institute of

Technology No 92, Xidazhi street, Harbin 150001, China CWS tianyh@hit.edu.cn

Mingyu Li Professor Harbin Institute of Technology

Shenzhen

HIT Campous, Shenzhen University Town, Xili, Shenzhen, 518055,China

CWS myli@hit.edu.cn

Wenya Li Professor Northwestern Polytechnical

University No.127, West Youyi Road, Xi'an, 710072,China CWS liwy@nwpu.edu.cn

Huaping Xiong Professor Beijing Institute of Aeronautical

Materials

Wenquan Town,Haidian Distr., Beijing, 100095,China

CWS xionghp69@yahoo.com.cn

Chuansong Wu Professor Shandong University

17923 Jingshi Road,Jinan, 250061,China CWS wucs@sdu.edu.cn

Baoqiang Cong Dr. Beihang University No.37 Xueyuan Rd. Haidian District,Beijing,100191,China

CWS congbq@buaa.edu.cn

Qiang Wang Dr. Beihang University No.37 Xueyuan Rd. Haidian District,Beijing,100191,China

CWS sy1207140@163.com

66

Xia Liu Senior

researcher

Shanghai Electric Power Generation Equipment Co.,

Ltd.

333 Niangchuan Road, Minhang District,Shanghai

CWS liuxia@shanghai-electric.com

Furong Chen Professor Inner Mongolia University of Technology

Inner Mongolia University of Technology, Hohhot, 010051,China

CWS cfr7075@163.com

Xiaoyan Li Professor Beijing University

of Technology No.100 Pingleyuan, Chaoyang District, Beijing,

China, 100124 CWS xyli@bjut.edu.cn

Shujun Chen Professor Beijing University

of Technology No.100 Pingleyuan, Chaoyang District, Beijing,

China, 100124 CWS sjchen@bjut.edu.cn

Hui Li Associate Professor

Beijing University of Technology

No.100 Pingleyuan, Chaoyang District, Beijing, China, 100124

CWS hui.li@bjut.edu.cn

Fan Jiang Dr. Beijing University

of Technology No.100 Pingleyuan, Chaoyang District, Beijing,

China, 100124 CWS jiangfan@bjut.edu.cn

Shengchuan Wu

Professor Southwest Jiaotong

University

No. 111, North Second Ring, Chengdu, 610031,PR China

CWS wusc@swjtu.cn

Zhenguo Sun Associate Professor

Tsinghua Uniersity Welding Building, Tsinghua，100084, University CWS sunzhg@tsinghua.edu.cn

Lei Liu Assistant Professor

Tsinghua Uniersity Welding Building, Tsinghua，100084, University CWS liulei@tsinghua.edu.cn

Linshu Wang Professor Chinese Welding

Society 2077 Chuangxin Rd.Harbin, 150028,China CWS wanglinshu59@sina.cn

Lijun He Senior

researcher China Welding

Magazine 2077 Chuangxin Rd.Harbin, 150028,China CWS zghjbjb@126.com

Zhiling Tian Professor China Iron & Steel Research Institute

Group

76 S.Xueyuan Rd., Haidian Distr.Beijing, 100081，

China CWS tianzhl@cisri.com.cn

Lianyong Xu Associate Professor

Tianjin University 92 Weijin Rd,Nankai Distr., Tianjin,

300072,China CWS xulianyong@tju.edu.cn