Dt-01/06/2015Comparisons of mechanical and metallurgical properties of GMAW,

FCAW & MCAW weldments of SA516 GR70 steel Material

Pandit Deendayal Petroleum UniversitySchool of Technology ,Mechanical Engineering

Sponsored project of Department ofScience and Technology, New Delhi

1

SupervisorDr. Vishvesh J Badheka, IWEAssociate Professor, Mechanical Engineering DeptSchool of Technology,Pandit Deendayal Petroleum University.

Review Presentation (4th Sem)

Presented ByPritesh J. PrajapatiRo.No- 13RME011PhD Student, PDPU

Content of Presentation

PhD journey Introduction.

GMAW FCAW MCAW

Gap Analyses. Research Plan Proposed Objectives Material Selection. Experimental Procedure. Acknowledgement.

PhD journey Introduction.

GMAW FCAW MCAW

Gap Analyses. Research Plan Proposed Objectives Material Selection. Experimental Procedure. Acknowledgement.

2

SEM WORK DONE DURATION REMARKSem -I Course work

1).Fundamentals of Welding (ME-704)2).Advanced welding processes (ME-701)3).Research Methodology (PET-701)

July-Dec2013

Good

Sem -II Compressive exam and Review ofLiterature survey

Jan-June2013

Good

PhD Journey Enrolled in July 2013

3

Sem -II Compressive exam and Review ofLiterature survey

Jan-June2013

Good

Sem -III Experiment-I July-Dec2014

Very good

Sem -IV Experiment-II Jan-June2015

4

IntroductionGMAW is an electric arc welding process

Fig.1

6Fig.2

FCAW, has a hollow wire with flux in the center, Just as the name states, a FluxCore.

The main difference between MIG welding and FCAW is, FCAW gets its shieldingfrom the flux core, so use at weld outdoors. MIG welding is the way the electrode isshielded from the air.

7The internal components of a metal cored wire are composed chiefly of the alloys,manganese, silicon, and in some cases, nickel. chromium and molybdenum as well as verysmall amounts of arc stabilizers such as sodium and potassium, with the balance being ironpowder.

Gap Analyses Existing literature available in the area of the GMAW and FCAW. Most of research

papers published are the comparison of the solid wire with flux cored wire.

Metal cored wires are the latest development in the area of advances consumables.There is general comparison of characteristics of wires (solid, flux cored and metalcored) are available but effect of different wire on mechanical and metallurgical isnot reported.

Conventionally root run are being filled with the GTAW process because it hasexcellent weld metal properties and subsequently passes with GMAW or SAWdepending on the size of the job.

In addition to the above mentioned detail there is very little research has beencarried out in the area of application of hybrid welds using GMAW, FCAW &MCAW process.

Mechanical and metallurgical properties of solid, flux cored wires ,metal coredwires are also will be compared with hybrid welds.

Existing literature available in the area of the GMAW and FCAW. Most of researchpapers published are the comparison of the solid wire with flux cored wire.

Metal cored wires are the latest development in the area of advances consumables.There is general comparison of characteristics of wires (solid, flux cored and metalcored) are available but effect of different wire on mechanical and metallurgical isnot reported.

Conventionally root run are being filled with the GTAW process because it hasexcellent weld metal properties and subsequently passes with GMAW or SAWdepending on the size of the job.

In addition to the above mentioned detail there is very little research has beencarried out in the area of application of hybrid welds using GMAW, FCAW &MCAW process.

Mechanical and metallurgical properties of solid, flux cored wires ,metal coredwires are also will be compared with hybrid welds.

8

Hybrid Welds

Hybrid welds in which root and filler pass filled with different process.

Hybrid Welding Process

9

Parameters Filler Wire diameter = 1.2mm. Welding Current - 200 A,Voltage - 28 V, Travel Speed 200

Shielding Gas Composition Ar/CO2 =90/10

I II III

ROOT SIDE GMAW FCAW MCAW

FILLER PASSES (OP-1) GMAW FCAW MCAW

Research Plan

FILLER PASSES (OP-1) GMAW FCAW MCAW

FILLER PASSES (OP-2) FCAW GMAW GMAW

FILLER PASSES (OP-3) MCAW MCAW FCAW

SAMPLE ID ROOT RUN FILLER RUN

A GMAW GMAW

B GMAW FCAW

C GMAW MCAW

D FCAW GMAW

E FCAW FCAW

11

E FCAW FCAW

F FCAW MCAW

G MCAW GMAW

H MCAW FCAW

I MCAW MCAW

Root passes andfiller pass filled withsolid wire flux coredand metal cord wire.

Root passes filled withmetal cord wire and fillerpass with solid wire.

Root passes -solid wire.filler pass with metal cordor flux cored wire.

Fig.3

Proposed Objectives

Experiments are made to in single V (60) groove joint design for 10mm thickSA516 Gr70 carbon steel plate using Solid wire (ER70S6), flux cored wire (E71T-1C), and Metal Cored wire (E70C-6M) of 1.2 mm in diameter.

Establishment of Welding Parameters for welding SA516 Gr70 Carbon steel plateusing GMAW ,FCAW and MCAW process.

Destructive and Non-destructive testing and characterization of the welded joint asper applicable standards is carried out.

Comparison of Metallurgical & Mechanical properties of GMAW, FCAW &MCAW welded Joints.

Experiments are made to in single V (60) groove joint design for 10mm thickSA516 Gr70 carbon steel plate using Solid wire (ER70S6), flux cored wire (E71T-1C), and Metal Cored wire (E70C-6M) of 1.2 mm in diameter.

Establishment of Welding Parameters for welding SA516 Gr70 Carbon steel plateusing GMAW ,FCAW and MCAW process.

Destructive and Non-destructive testing and characterization of the welded joint asper applicable standards is carried out.

Comparison of Metallurgical & Mechanical properties of GMAW, FCAW &MCAW welded Joints.

13

Material Selection

SA516Gr70 carbon steel materials are widely used in heavy fabrication applicationin which cost saving factor and high strength are most important.

SA516 Grade 70 offers greater tensile and yield strength when compared to ASTMSA516 Grade 65 and can operate in even lower temperature service.

Table 1. Mechanical properties of consumables

Mechanical PropertiesSolid Wire

(ER70S-6)Flux Cored Wire

(E71T-1C)

Metal CoredWire

(E70C-6M)

Base metal

(SA516Gr70)

SA516Gr70 carbon steel materials are widely used in heavy fabrication applicationin which cost saving factor and high strength are most important.

SA516 Grade 70 offers greater tensile and yield strength when compared to ASTMSA516 Grade 65 and can operate in even lower temperature service.

Table 1. Mechanical properties of consumables

14

Solid Wire

(ER70S-6)Flux Cored Wire

(E71T-1C)

Metal CoredWire

(E70C-6M)

Yield Strength 427 MPa 605 MPa 448 MPa 446.9 MPa

Tensile Strength 529 MPa 579 MPa 549 MPa 590.60 MPa

Elongation 26% 31 % 31 % 24.8 %

CVN Impact Value

(Temp. C)35 J (30C)

80J (-20C) 103J(-30 C)

48J (-29C) 62J(-18C)

---

Shielding Gas --- 100% CO275% Ar-25%

CO2

---

Contents Solid Wire

(ER70S-6)Flux cored

wire

(E71T-1C)

Metal cored wire

(E70C-6M)Base metal

(SA516Gr70)

C 0.07 0.03 0.048 0.186

Si 0.86 0.56 0.582 0.322

Mn 1.44 1.29 1.375 1.112

0.014

Table 2. Chemical composition of the filler wire and SA516 Gr70 carbon steel material.

P 0.014 0.011 0.014 0.014

S 0.008 0.005 0.012 0.009

Cr 0.025 0.04 0.023 0.030

Ni 0.014 0.02 0.014 0.026

Mo 0.002 0.01 0.001 0.019

V 0.002 0.02 0.004 0.001

Nb N/A N/A 0.002 Nil

Cu 0.15 0.01 0.015 0.033

15

Experiment Procedure.

16

Power Source Equipment

Photograph of Experimental Setup

Ar/CO2Gas Mixer

Power Source Equipment

WeldingTorch

SPMHead

StandardGas

Cylinders

FumeExtractor

Data Monitoring System

Above setup available at PDPU( Research work carried out under sponsored project ofDepartment of Science and Technology (DST), New Delhi)

Fig.4

Experimental Condition

Base metal : SA516Grade70 Size : 30010010 mm Joint Design : V- groove (60 angle, Root Gap= 04 mm) Wire Type : 1.2 mm Solid (ER70S6), Flux cored (E71T-1C/M), MetalCored(E70C-6M) Welding Variable:

a) Normal Fe modeb) Welding Current -200 Ac) Welding Voltage 28 Vd) Travel Speed 200mm/mine) Nozzle to Plate Distance -15 mmf) Electrode Extension -8 to 10 mmg) Shielding Gas -90%Ar + 10% CO2

Base metal : SA516Grade70 Size : 30010010 mm Joint Design : V- groove (60 angle, Root Gap= 04 mm) Wire Type : 1.2 mm Solid (ER70S6), Flux cored (E71T-1C/M), MetalCored(E70C-6M) Welding Variable:

a) Normal Fe modeb) Welding Current -200 Ac) Welding Voltage 28 Vd) Travel Speed 200mm/mine) Nozzle to Plate Distance -15 mmf) Electrode Extension -8 to 10 mmg) Shielding Gas -90%Ar + 10% CO2

18

Fig.5 Joint Design

Fig.6.Photographs of welded plates

FMFSFF

19

Carbon steel plate SA516Gr70 welded using FF shows that both root pass and fillerpass filled with flux cored wire.

FS indicate Hybrid welds in which root pass filled with flux cored wire and fillerpass with solid wire.

FM indicate Hybrid shows that root pass filled with flux cored wire and filler passwith metal cored wired.

Table 3. Full plate Experimental Data

ID Current in Amp Voltage in VoltWeldingspeed inmm/min

Heat input KJ/mm

Set 1 (*) 2 (*) ActualAvg.(*) Set 1 (*) 2 (*)ActualAvg.(*) Set Cal. Cal.1 (*) Cal.2 (*)

ActualAvg.(*)

FF 200 273 282 277.5 28 27.9 28 27.95 200 1.68 2.28 2.36 2.32

FS 200 234 272 253.0 28 27.9 28.1 28.00 200 1.68 1.95 2.29 2.12

FM 200 228 271 249.5 28 27.9 28 27.95 200 1.68 1.90 2.27 2.09

20

1: First Trial 2: Second Trial .ctual (*): Values recorded by online data monitoring system (During Welding).

KJ/mm Where, V- Voltage,I- Current,S- Welding Speed-Welding Efficiency 0.9

Angular Distortion

Dial Indicator

21 Angular distortion measurement were carried as per the following procedure.

Fig.7 Schematic diagram of angular distortion measurements [30]

Weldingprocess

VerticalDisplacement Z in mm

HorizontalDisplacement

X in mm

Root runTemp.

Filler runTemp.

Avg. PeckTemperature

FF 4.66 100 2.68 420 394 407.0 Co

FS 4.98 100 2.66367 411 389Co

FM 3.94 100 1.72287 358 322.5 Co

Table 4. Angular Distortion and peck temperature Data

Contact typethermocouple

(K-Type- Nibase,chromel & alumel)

22Fig.(8) Calculated Angular Distortions

Contact typethermocouple

(K-Type- Nibase,chromel & alumel)

012345

FF FS FM

% Ang

u Dist

Consumables

Average pick temperature with flux coredwire is higher compare to other welds, becauseof high input recorded using flux cored wire, asshown in table 4That may be the reason for higher angulardistortion in FF and lowest in FM.

Macro preparation

The test specimen were cut from the welded plate after removing run on and runoff.

Each metallographic specimens were prepared by:- Mechanical grinding.- Polishing (120 and 320 grit silicon carbide),- Etching (solution of 35% concentrated HCL (60%) and 35%

concentrated HNO3 (40%) for 2-3 min to produce a bright surface.

The test specimen were cut from the welded plate after removing run on and runoff.

Each metallographic specimens were prepared by:- Mechanical grinding.- Polishing (120 and 320 grit silicon carbide),- Etching (solution of 35% concentrated HCL (60%) and 35%

concentrated HNO3 (40%) for 2-3 min to produce a bright surface.

23

FF FS FM

Fig.9

Table 5. Radiography Test Results of Full Plate.Sample Id Film Size (inch) Position Observation

FF 3 X 15 A/B Miner defect arereported andaccepted withinstandard

FS 3 X 15 A/B

FM 3 X 15 A/B

FFFF

24

FSFS

FMFM

25

Figure 10. . Plate less than 19mm Thickness Procedure Qualification(Pressurevessel and boiler code. ASME, Section IX) [25].

Destructive TestingTable 6. Tensile Test Specimens

Sample IdTensile test photos

RemarksFirst set

FF Specimen break from parent metal

26

FS Specimen break from parent metal

FM Specimen break from parent metal

Table- 7. Yield Strength and Tensile Strength for Welded joints.Sample Id Set of

ExperimentsYield

Strength(MPa)

Avg. YieldStrength(MPa)

TensileStrength(MPa)

Avg. TensileStrength(MPa)

Observation

FF 1387

359611

565 Broken fromparent

330 519

382 517

27

FS 2

382

385517

568 Broken fromparent

388 619

FM 3375

379562

559 Broken fromparent

382 555

Average yield strength and tensile strength values are higher for FS hybrid weld.

Fig.11 Effect of wires on mechanical yieldstrength

Fig.12 Effect of wires on mechanical Tensilestrength.

300320340360380400420

FF FS FM

YS in

MPa

Consumables

500520540560580600

FF FS FM

TS in

MPa

Consumables

28

Fig.11 Effect of wires on mechanical yieldstrength

Fig.12 Effect of wires on mechanical Tensilestrength.

This may be due to the externally fine microstructure (ferrite, Widmanstttenferrite, and acicular ferrite) developed.Additionally, it is future conform through the weld metal chemical analysis as shown intable 9.it was found that C-Mn-S for FS weld metal is higher compared to filler metal.The variation in properties across the weld can be attributed

Table-8 %Elongation Area for welded Joints

SampleId

Set ofspecimen

%Elongation

Avg. %Elongation

FF1 25 232 21

FS1 08

152 22

FM1 20

232 26

29

05

1015202530

FF FS FM

% Elon

gation

ConsumablesFig.(13) Effect of wires on % Elongation

Result:- Percent elongation is higher forflux cored weld (FF) as compare to hybridwelds

Table-9 Joint efficiency of welded joint.

Sample Id Weld Joint Strengthin MPa

Joint Efficiency in %

FF 565.05 96

FS 568.00 96

FM 558.20 95

Result:- Joint efficiency of weldedjoint is defined as a ratio of strengthof weld metal to the strength ofparent metal.Strength of parent metal is590MPa.

Joint efficiency is very by 2%only.

100

30Fig. (14) Different wires on joint efficiency

Result:- Joint efficiency of weldedjoint is defined as a ratio of strengthof weld metal to the strength ofparent metal.Strength of parent metal is590MPa.

Joint efficiency is very by 2%only.

80859095

100

FF FS FM

Joint

Efficie

ncy

Consumables

Table -8 Bend test photos

ID

Bend Test

RemarksFace bend Root BendSet. 1 Set. 2

FFPass

31

FSPass

FM Pass

Table -9 Impact Test Results.

Weldingprocess

Charpy impact test at -49 C. energy absorbed in Joule

set of specimen Avg.Weld

set of specimen Avg.HAZI II II I I III

FF 46 44 38 43 32 38 36 35

FS 44 50 52 49 26 22 22 24

FM 20 24 18 21 24 28 22 25

60

32

(G) Impact test results Weld and HAZ

Fig.(15) Impact test results Weld and HAZ

Result:- Highest Impact value reported forFS welds and lowest for FM welds. Whilein HAZ highest impact values reported forFF..

1015202530354045505560

FF FS FM

Impa

ct Tes

t in J

Consumables

WELD

HAZ

Vickers Hardness Measurement Specimens prepared for macrostructure observation were utilized for VHN measurement.

Specification of the machine as follow. Vickers hardness was measured as per standard ASTM,A 370-07 in both in both

transverse(weld metal, HAZ, and parent metal) direction and vertical(root to filler pass)direction.

Each indentation was separated by 1mm at 10 Kg for macro hardness and 300grms formicro hardness.

Equipment : ESEWAY-4000.Modal-4302 Load : 10 Kg & 300grm Dwell Time : 15 Sec. Objective : 20 X

Specimens prepared for macrostructure observation were utilized for VHN measurement.Specification of the machine as follow.

Vickers hardness was measured as per standard ASTM,A 370-07 in both in bothtransverse(weld metal, HAZ, and parent metal) direction and vertical(root to filler pass)direction.

Each indentation was separated by 1mm at 10 Kg for macro hardness and 300grms formicro hardness.

Equipment : ESEWAY-4000.Modal-4302 Load : 10 Kg & 300grm Dwell Time : 15 Sec. Objective : 20 X

33Fig- 16: Vicker hardness tester - (ESEWAY-4000.Modal-4302) at PDPU

Fig17. VHN at different (transverse direction) zones at (HV10)

100115130145160175190205220235250265280

-15

-14

-13

-12

-11

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

HV

10

Dist. from Center of weld to both side

FF

FS

FM

34

Fig 18. VHN at different (vertical direction) zones at (HV10)

150165180195210225240255270285300

-5 -4 -3 -2 -1 0 1 2 3 4 5

HV

10

Dist. from Center of weld to both side

FF

FS

FM

Root side Filler side

Fig 19. VHN at different (transverse direction) zones at (HV0.3)

Fig 20. VHN at different (Vertical direction) zones at (HV0.3)

100115130145160175190205220235250265280295310325340355370385400

-15

-14

-13

-12

-11

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

HV

0.3

Dist. from Center of weld to both side

FF

FS

FM

35

Fig 20. VHN at different (Vertical direction) zones at (HV0.3)

120140160180200220240260280300320340360380400

-5 -4 -3 -2 -1 0 1 2 3 4 5

HV

0.3

Dist. from Center of weld to both side

FF

FSFM

Root side Filler side

Contentin %

FF FS FM

Filler

WireWeldedSample Filler Wire

WeldedSample Filler Wire

WeldedSample

Carbon 0.07 0.112 0.03 0.092 0.048 0.108

Manganese 1.44 1.510 1.29 1.415 1.375 1.309

TABLE 10. Chemical analysis of weld metal

36

Silicon 0.86 0.618 0.56 0.674 0.582 0.391

= increased and = decreased compared with filler wire %.

From above table , C-Mn-Si for FS welds metal is higher compared to filler metal.

In second cases, C-Mn % for FF welds metal is higher compared to filler metal, while Si islow record. C for FM weld higher while Mn-Si is lower compared to filler metal.

From table 10, in some cause % for Manganese and % of silicon in weld metal isreduced as compared to filler wire because of all this element react with oxygenstrongly during welding.

The loss of manganese and silicon may be caused by oxidation reactions in theweld pool: [20]

Carbon, decreases. the ductility, formability, weldability and increases the strengthand hardenability.

Manganese slightly increases the strength of ferrite, and also increases the hardnesspenetration of steel in the quench by decreasing the critical quenching speed. Thisalso makes the steel more stable in the quench

Silicon is used as a deoxidizer in the manufacture of steel. It slightly increases the strength of ferrite, and when used in conjunction with other

alloys can help increase the toughness and hardness penetration of steel.

From table 10, in some cause % for Manganese and % of silicon in weld metal isreduced as compared to filler wire because of all this element react with oxygenstrongly during welding.

The loss of manganese and silicon may be caused by oxidation reactions in theweld pool: [20]

Carbon, decreases. the ductility, formability, weldability and increases the strengthand hardenability.

Manganese slightly increases the strength of ferrite, and also increases the hardnesspenetration of steel in the quench by decreasing the critical quenching speed. Thisalso makes the steel more stable in the quench

Silicon is used as a deoxidizer in the manufacture of steel. It slightly increases the strength of ferrite, and when used in conjunction with other

alloys can help increase the toughness and hardness penetration of steel.

37

(a) Microstructure ofFCAWParent

(b) Microstructure of PM &HAZleft (interface)

(c) Microstructure ofTop run

Microstructure of the FF Samples at (200X)

Normalweld

38

(d) Microstructure ofMiddle run

(f) Microstructure of Root run

Hybridweld

(g) Microstructure ofPM &HAZ Right

(interface)

(a) Microstructure ofParent

(b) Microstructure of PM &HAZleft (interface)

(c) Microstructure ofTop run

Hybridweld

Microstructure of the FS Samples at (200X)

(d) Microstructure ofMiddle run

(e) Microstructure of Root run

Hybridweld

(f) Microstructure of PM &HAZ Right(interface)

(a) Microstructure ofParent (b) Microstructure of PM &HAZ

left(interface)

(c) Microstructure ofTop run

Hybridweld

Microstructure of the FM Samples at (200X)

(d) Microstructure ofMiddle run

(g) Microstructure ofRoot run

(h) Microstructure ofPM &HAZ

Right (interface)(f) Microstructure ofMiddle run (50 X)

The properties of the steel depends upon the microstructure. Decreasing the size of thegrains and decreasing the amount of pearlite improve the strength, ductility andtoughness of the steelMicrostructure investigation reflects the extremely fine grain structure of weld and aswell HAZ of FS weld.It has two major constituents, which are ferrite and pearlite.Its major components include allotriomorphic ferrite, Widmansttten (called side plateferrite) ferrite, and acicular ferrite.The dark regions are the microstructure is the pearlite. it is made up from a finemixture of ferrite and iron carbide.The light coloured region is the ferrite. boundary ferrite is called allotriomorphicferrite.

41

The properties of the steel depends upon the microstructure. Decreasing the size of thegrains and decreasing the amount of pearlite improve the strength, ductility andtoughness of the steelMicrostructure investigation reflects the extremely fine grain structure of weld and aswell HAZ of FS weld.It has two major constituents, which are ferrite and pearlite.Its major components include allotriomorphic ferrite, Widmansttten (called side plateferrite) ferrite, and acicular ferrite.The dark regions are the microstructure is the pearlite. it is made up from a finemixture of ferrite and iron carbide.The light coloured region is the ferrite. boundary ferrite is called allotriomorphicferrite.

42

Figure13. Fracture morphology (SEM image) of tensile specimen fractured at room temperature, (a) FF sample,(b) FS sample. (C) FM sample. The inclusion is indicated by the arrow. The EDAX spectra of the inclusions areshown in Fig

FF sample FS sample

In all sample, the results of the EDXanalyses indicated that the inclusionscontained manganese, iron, carbon andnickel, silicon as shown in Fig .

43

Small spots within the ferrite grains. These inclusions are silicon oxides and manganeseoxides, and sulphides etc.The difference in composition of the inclusions is due to the different sources of theinclusions.In MAG, the Impurities mainly arose from the shielding gas. In FCAW, the impuritiesmainly arose from the ux and shielding gas. [18]

FM sample

Image Analyser ERDA, Baroda

Model: Olympus

Scanning ElectronMicroscope - PDPU

Model : ZEISS ULTRA 55 44

CONCLUSIONS The angular distortion is higher with flux cored wire compare to hybrid weld. Pick temperature reported with flux cored wire is higher compare to hybrid weld

which shown that high hear input with welding with flux cored wire. Yield strength and tensile strength values are higher for with FS hybrid weld. Percent elongation is higher for flux cored wire as compare to hybrid welds During tensile test all specimens failed from parent material; means welded joints

are stronger then parent metal. Samples welded with different consumables shows good integrity of welded

joints during bend test. Excellent impact toughness of the weld metal reported for the FS hybrid welds

compared to other cases. Higher macro and micro hardness value reported for flux cored welds compare to

others hybrid welds. Weld metal microstructure confirm the presence of allotriomorphic ferrite,

Widmansttten ferrite, and acicular ferrite in the weld metal.

The angular distortion is higher with flux cored wire compare to hybrid weld. Pick temperature reported with flux cored wire is higher compare to hybrid weld

which shown that high hear input with welding with flux cored wire. Yield strength and tensile strength values are higher for with FS hybrid weld. Percent elongation is higher for flux cored wire as compare to hybrid welds During tensile test all specimens failed from parent material; means welded joints

are stronger then parent metal. Samples welded with different consumables shows good integrity of welded

joints during bend test. Excellent impact toughness of the weld metal reported for the FS hybrid welds

compared to other cases. Higher macro and micro hardness value reported for flux cored welds compare to

others hybrid welds. Weld metal microstructure confirm the presence of allotriomorphic ferrite,

Widmansttten ferrite, and acicular ferrite in the weld metal.

45

While comparing the mechanical properties of the FF welds with FS and FM. It wasfound that FS weld is better compared to others in terms of YS, TS JE and weldimpact. This may be due to the externally fine microstructure (ferrite,Widmansttten ferrite, and acicular ferrite) developed.

Additionally, it is future conform through the weld metal chemical analysis asshown in table 9.it was found that C-Mn-S for FS weld metal is higher compared tofiller metal.

46

Paper submitted

1.International Journal of Pressure Vessels and Piping (ELSEVIER).Impact Factor: 1.532,Date-26/12/2014, DC ON 12/12/2014

Title: The effect of welding consumables on the Mechanical and Metallurgicalproperties of carbon Steel Material. Current Status: Paper under review.

2. Journal of Pressure Vessel Technology ,ASMEsubmitted on Date-13/04/2015

Title: The effect of Hybrid Weldments on the Mechanical and Metallurgical.Properties of carbon Steel Material.

Current Status: comments received from reviewer.

47

Paper submitted

1.International Journal of Pressure Vessels and Piping (ELSEVIER).Impact Factor: 1.532,Date-26/12/2014, DC ON 12/12/2014

Title: The effect of welding consumables on the Mechanical and Metallurgicalproperties of carbon Steel Material. Current Status: Paper under review.

2. Journal of Pressure Vessel Technology ,ASMEsubmitted on Date-13/04/2015

Title: The effect of Hybrid Weldments on the Mechanical and Metallurgical.Properties of carbon Steel Material.

Current Status: comments received from reviewer.

Originality AcceptableSignificance AcceptableScientific relevance AcceptableCompleteness AcceptableAcknowledgment of the Work of others by References AcceptableOrganization MarginalClarity of Writing MarginalClarity of Tables, Graphs, and Illustrations MarginalIn your opinion, is the technical treatment plausible and free of technicalerrors?

Yes

Reviewer 1:

48

In your opinion, is the technical treatment plausible and free of technicalerrors?

Yes

Have you checked the equations? NoAre you aware of prior publication or presentation of this work? NoIs the work free of commercialism? YesIs the title brief and descriptive? YesDoes the abstract clearly indicate objective, scope, and results? Yes

This paper is Not Acceptable (Revision required; resubmit as Tech. Brief) . The qualityof the paper is Good.

Recommendation

The work appears to be original and meaningful.

Originality Acceptable

Significance Acceptable

Scientific relevance Acceptable

Completeness Marginal

Acknowledgment of the Work of others by References Marginal

Organization Acceptable

Clarity of Writing Poor

Clarity of Tables, Graphs, and Illustrations Marginal

In your opinion, is the technical treatment plausible and free of technical errors? Yes

Reviewer 2:

49

In your opinion, is the technical treatment plausible and free of technical errors? Yes

Have you checked the equations? Yes

Are you aware of prior publication or presentation of this work? No

Is the work free of commercialism? Yes

Is the title brief and descriptive? Yes

Does the abstract clearly indicate objective, scope, and results? No

This paper is Not Acceptable (Revision and resubmitted required) . The quality of thepaper is Average.

Recommendation

Internal Assessment seminar topics

(1) Non- Destructive testing of welds- all.(Delivered on 05/09/2013)(2) Heat Flow during welding. (Delivered on 10/10/2013)(3) M.Tech presentation. (Delivered on 27/01/ 2014)(4) Destructive testing of welds- all. (Delivered 15th May 2014)(5) Welding symbol (Delivered 29th Des 2014)(6) Welding Metallurgy (will be deliver before 11nd June2015)

Internal Assessment seminar topics

(1) Non- Destructive testing of welds- all.(Delivered on 05/09/2013)(2) Heat Flow during welding. (Delivered on 10/10/2013)(3) M.Tech presentation. (Delivered on 27/01/ 2014)(4) Destructive testing of welds- all. (Delivered 15th May 2014)(5) Welding symbol (Delivered 29th Des 2014)(6) Welding Metallurgy (will be deliver before 11nd June2015)

References

1. American Welding Society - Welding Hand book, Welding Processes, Eighth Edition - Vol.II, pp 110, pp 157-190.2. American Society of Metals Handbook, Vol. 6 Welding, Brazing and Soldering, Published in 1993, pp 582-583.3. www.esabna.com, "Advantages and Disadvantages of metal cored wire".4. Nasir Ahmed, "New development in advance welding", Pub. Wood Head publishing limited Cambridge, England; pp 23.5. Stanley E. Ferree, Michael S, Sierdzinski, "Stainless steel metal cored wires for welding automotive exhaust systems" ESAB

Welding and Cutting Products, Hanover (PA) USA. Svetsaren nr i , 2000, pp 15-18.6. Kevin A. Lyttle, Praxair, Inc Senior Development Associate; "Metal Cored Wire: Where Do They Fit In Your Future?" Reprinted

from Welding Journal, Oct. 1996, pp 35-38.7. www.esabmanualcom, "Flux Core arc Welding, ESAB".8. David Widgery; Tubular wire welding, Jaico Publishing House.9. Washington alloy co. www.weldingwire.com.10. Avesatar welding www.avestarwelding.com.11. BOC, IPRM 2006: Section 4: Welding processes.12. BOC, AU: IPRM 2007: Section 8: Consumables.13. M. Suban, J. Tusek, "Dependance of melting rate in MIG/MAG welding on the type of shielding gas used", Journal of Materials

Processing Technology 119 (2001), pp 185-192.14. American Society of Metals Handbook, Vol. 6 Welding, Brazing and Soldering, Published in 1993, pp 163-174.15. Tom Myers,"Choosing a shielding Gas for FCAW", A senior application engineer, The Lincoln Electric Co; Cleveland, Ohio.16. John Norrish, -Advanced welding processes technologies and process control", Pub. Wood.17. Head publishing limited Cambridge", England pp 108.18. V. V. Vaidya, "Theory and practice of shielding gas mixtures for semiautomatic welds", Director, welding Technology and Business

Development, Air Liquide Canada Inc., Canada.19. M Menzel, "The influence of individual components of an industrial gas mixture on the welding process and the properties of

welded joints". Linde Gas Poland; Welding International 2003 17 (4) 262-264.20. .S. Mukhopadhyay and T.K.Pal.; "Effect of shielding gas mixture on gas metal arc welding of HSLA steel using solid and flux-cored

wires". Welding Technology Centre, Metallurgical Engineering Department, Jadavpur University, Kolkata.21. AMOS DAVIS, business development manager, "Optimizing Metal Cored Performance" Hobart Brothers Company, Feb 1, 2009;

12:00 PM.22. W. F. Garth Stapon, "Using Flux cored and Metal Cored Wire". Praxair. Inc. Marketing Manager Metal Fabrication; Reprinted from

Practical Welding Today Jan/Feb 2000.23. V. Vel Murugan and V. Gunaraj, "Effect of process parameters on Angular Distortion of gas metal arc welded structural steel plates",

Welding Journal, November 2005.51

References

1. American Welding Society - Welding Hand book, Welding Processes, Eighth Edition - Vol.II, pp 110, pp 157-190.2. American Society of Metals Handbook, Vol. 6 Welding, Brazing and Soldering, Published in 1993, pp 582-583.3. www.esabna.com, "Advantages and Disadvantages of metal cored wire".4. Nasir Ahmed, "New development in advance welding", Pub. Wood Head publishing limited Cambridge, England; pp 23.5. Stanley E. Ferree, Michael S, Sierdzinski, "Stainless steel metal cored wires for welding automotive exhaust systems" ESAB

Welding and Cutting Products, Hanover (PA) USA. Svetsaren nr i , 2000, pp 15-18.6. Kevin A. Lyttle, Praxair, Inc Senior Development Associate; "Metal Cored Wire: Where Do They Fit In Your Future?" Reprinted

from Welding Journal, Oct. 1996, pp 35-38.7. www.esabmanualcom, "Flux Core arc Welding, ESAB".8. David Widgery; Tubular wire welding, Jaico Publishing House.9. Washington alloy co. www.weldingwire.com.10. Avesatar welding www.avestarwelding.com.11. BOC, IPRM 2006: Section 4: Welding processes.12. BOC, AU: IPRM 2007: Section 8: Consumables.13. M. Suban, J. Tusek, "Dependance of melting rate in MIG/MAG welding on the type of shielding gas used", Journal of Materials

Processing Technology 119 (2001), pp 185-192.14. American Society of Metals Handbook, Vol. 6 Welding, Brazing and Soldering, Published in 1993, pp 163-174.15. Tom Myers,"Choosing a shielding Gas for FCAW", A senior application engineer, The Lincoln Electric Co; Cleveland, Ohio.16. John Norrish, -Advanced welding processes technologies and process control", Pub. Wood.17. Head publishing limited Cambridge", England pp 108.18. V. V. Vaidya, "Theory and practice of shielding gas mixtures for semiautomatic welds", Director, welding Technology and Business

Development, Air Liquide Canada Inc., Canada.19. M Menzel, "The influence of individual components of an industrial gas mixture on the welding process and the properties of

welded joints". Linde Gas Poland; Welding International 2003 17 (4) 262-264.20. .S. Mukhopadhyay and T.K.Pal.; "Effect of shielding gas mixture on gas metal arc welding of HSLA steel using solid and flux-cored

wires". Welding Technology Centre, Metallurgical Engineering Department, Jadavpur University, Kolkata.21. AMOS DAVIS, business development manager, "Optimizing Metal Cored Performance" Hobart Brothers Company, Feb 1, 2009;

12:00 PM.22. W. F. Garth Stapon, "Using Flux cored and Metal Cored Wire". Praxair. Inc. Marketing Manager Metal Fabrication; Reprinted from

Practical Welding Today Jan/Feb 2000.23. V. Vel Murugan and V. Gunaraj, "Effect of process parameters on Angular Distortion of gas metal arc welded structural steel plates",

Welding Journal, November 2005.

26. 26. ASTM-A ferrous metals 2006 SA 516 Gr-70.27. Gas metal are welding of carbon steel (PRAXAIR).28. Mario Teske and Fabio Martins, The influence of the shielding gas composition on GMA welding of ASTM A 516 steel. Federal Technological

University of Parana, Campus Curitiba, Brazil.29. Cicero Murta Diniz Starling, Paulo Jose Modenesi, and Tadeu Messias Donizete Borba, Comparison of operational performance and bead characteristics

when welding with different tubular wires, Welding international, Vol. 24, No 8, August 2010, 579-592.30. R. M. Mirza and R. Gee;Effects of shielding gases on weld diffusible hydrogen contents using cored wire; Science and Technology of welding and

joining, 1999, vol. 4, no.2.31. Ravi Menon,; Recent advances in cored wires for hardfacing. Vice President, Technology, Stoody Co; a Thermadyne company, Bowling Green.32. N. M. Ramini DE Rissone; H. G. Svoboda; E. S. Surian, and L. A. DE Vedia; Influence of procedure variables on C-Mn-Ni-Mo metal cored wire ferrites

all weld metal. Supplement to the welding journal, September 2005.33. Lucilene de Oliveira Rodrigues, Anderson Paulo de Paiva and Sebastiao Carlos de Costa; Optimization of the FCAW process by bead geometry

analysis, Welding International, Vol.23, No.4, Aprial 2009, 261-269.34. D. D. Harwig; D. P. Longeneker and J. H. Cruz; Effect of welding parameters and electrode atmospheric exposure on the diffusible hydrogen content of

shielding flux cored arc welds, AWS welding Journal, September 1999.35. K. S. Bang; D. H. Jung; C. Park and W. S. Chang; Effect of welding parameters on tensile strength of weld metal in flux cored arc welding, Science and

Technology of welding and joining, 2008, vol. 13, no.6, 509.36. T. Kannan & J. Yoganandh, Effect of process parameters on clad bead geometry and its shape relationships of stainless steel claddings deposited by

GMAW, Int Adv Manuf Technology (2010), 30: 1083-1095.37. ESAB; Welding Handbook; Eighth edition.38. Her-Yueh Huang; Effects of activating flux on the welded joint characteristics in gas metal arc welding. Department of Materials Science and

Engineering, National Formosa University, Yunlin 632, Taiwan.39. The ABC's of Arc Welding; KOBELCO WELDING TODAY.40. www.wikipedia.com Equivalent Carbon Content.41. H. K. D. H. Bhadeshia and Sir Robert Honeycombe; Steels: Microstructure and Properties: Third edition; Published by Elsevier Ltd. 2006.42. Flux Cored Arc Welding Equipment, Setup, and Operation Chapter no 3.43. Welding Kita-Shinagawa, Shinagawa-Ku Essential Factors in Gas Metal Arc 2011 by Kobe Steel, Ltd Fourth Edition , Tokyo, 141-8688 Japan.44. Shielding Gases Selection Manual (Praxair).45. British patent 8580854, Mar 29, 1957.46. Welding Design and Fabrication, a Penton Media, Inc. publication. May 1999 6/8/1999, New AWS Specs-Electrode Selection.47. Nick Kapustka Arc Welding Capabilities at EWI, November 29, 2012 .ewi.org 614.688.5000.48. Jeff Nadzam, Senior Application Engineer Lincon electrical, Gas Metal Arc Welding , Carbon, Low Alloy, and Stainless Steels and Aluminum, MIG

C4.200 9/06.49. Syarul Asraf Mohamat,, Izatul Aini Ibrahim, , Amalina Amir , Abdul Ghalib The Effect of Flux Core Arc Welding (FCAW) processes on different

parameters SciVerse ScienceDirect , International Symposium on Robotics and Intelligent Sensors 2012 (IRIS 2012) Procedia Engineering 41 ( 2012 )1497 1501.

50. Vishvesh J Badheka , Hardik Vyas Comparisons of GMA, FCA and MCA weldments of SA516 Gr70 Steel Material.51. Ramy Gadallah , Raouf Fahmy ,Tarek Khalifa, Alber Sadek Influence of Shielding Gas Composition on the Properties of Flux-Cored Arc Welds of

Plain Carbon Steel.International Journal of Engineering and Technology Innovation, vol. 2, no. 1, 2012, pp. 01-12.

52. ASME. Pressure vessel and boiler code. New York (NY): ASME, Section IX.53. K.E. Dorschu. Factors affecting weld metal properties in carbon and low alloy pressure vessel steels. sponsored by the pressure vessel research committee

of the welding research council, WRC bulletin 231.

26. 26. ASTM-A ferrous metals 2006 SA 516 Gr-70.27. Gas metal are welding of carbon steel (PRAXAIR).28. Mario Teske and Fabio Martins, The influence of the shielding gas composition on GMA welding of ASTM A 516 steel. Federal Technological

University of Parana, Campus Curitiba, Brazil.29. Cicero Murta Diniz Starling, Paulo Jose Modenesi, and Tadeu Messias Donizete Borba, Comparison of operational performance and bead characteristics

when welding with different tubular wires, Welding international, Vol. 24, No 8, August 2010, 579-592.30. R. M. Mirza and R. Gee;Effects of shielding gases on weld diffusible hydrogen contents using cored wire; Science and Technology of welding and

joining, 1999, vol. 4, no.2.31. Ravi Menon,; Recent advances in cored wires for hardfacing. Vice President, Technology, Stoody Co; a Thermadyne company, Bowling Green.32. N. M. Ramini DE Rissone; H. G. Svoboda; E. S. Surian, and L. A. DE Vedia; Influence of procedure variables on C-Mn-Ni-Mo metal cored wire ferrites

all weld metal. Supplement to the welding journal, September 2005.33. Lucilene de Oliveira Rodrigues, Anderson Paulo de Paiva and Sebastiao Carlos de Costa; Optimization of the FCAW process by bead geometry

analysis, Welding International, Vol.23, No.4, Aprial 2009, 261-269.34. D. D. Harwig; D. P. Longeneker and J. H. Cruz; Effect of welding parameters and electrode atmospheric exposure on the diffusible hydrogen content of

shielding flux cored arc welds, AWS welding Journal, September 1999.35. K. S. Bang; D. H. Jung; C. Park and W. S. Chang; Effect of welding parameters on tensile strength of weld metal in flux cored arc welding, Science and

Technology of welding and joining, 2008, vol. 13, no.6, 509.36. T. Kannan & J. Yoganandh, Effect of process parameters on clad bead geometry and its shape relationships of stainless steel claddings deposited by

GMAW, Int Adv Manuf Technology (2010), 30: 1083-1095.37. ESAB; Welding Handbook; Eighth edition.38. Her-Yueh Huang; Effects of activating flux on the welded joint characteristics in gas metal arc welding. Department of Materials Science and

Engineering, National Formosa University, Yunlin 632, Taiwan.39. The ABC's of Arc Welding; KOBELCO WELDING TODAY.40. www.wikipedia.com Equivalent Carbon Content.41. H. K. D. H. Bhadeshia and Sir Robert Honeycombe; Steels: Microstructure and Properties: Third edition; Published by Elsevier Ltd. 2006.42. Flux Cored Arc Welding Equipment, Setup, and Operation Chapter no 3.43. Welding Kita-Shinagawa, Shinagawa-Ku Essential Factors in Gas Metal Arc 2011 by Kobe Steel, Ltd Fourth Edition , Tokyo, 141-8688 Japan.44. Shielding Gases Selection Manual (Praxair).45. British patent 8580854, Mar 29, 1957.46. Welding Design and Fabrication, a Penton Media, Inc. publication. May 1999 6/8/1999, New AWS Specs-Electrode Selection.47. Nick Kapustka Arc Welding Capabilities at EWI, November 29, 2012 .ewi.org 614.688.5000.48. Jeff Nadzam, Senior Application Engineer Lincon electrical, Gas Metal Arc Welding , Carbon, Low Alloy, and Stainless Steels and Aluminum, MIG

C4.200 9/06.49. Syarul Asraf Mohamat,, Izatul Aini Ibrahim, , Amalina Amir , Abdul Ghalib The Effect of Flux Core Arc Welding (FCAW) processes on different

parameters SciVerse ScienceDirect , International Symposium on Robotics and Intelligent Sensors 2012 (IRIS 2012) Procedia Engineering 41 ( 2012 )1497 1501.

50. Vishvesh J Badheka , Hardik Vyas Comparisons of GMA, FCA and MCA weldments of SA516 Gr70 Steel Material.51. Ramy Gadallah , Raouf Fahmy ,Tarek Khalifa, Alber Sadek Influence of Shielding Gas Composition on the Properties of Flux-Cored Arc Welds of

Plain Carbon Steel.International Journal of Engineering and Technology Innovation, vol. 2, no. 1, 2012, pp. 01-12.

52. ASME. Pressure vessel and boiler code. New York (NY): ASME, Section IX.53. K.E. Dorschu. Factors affecting weld metal properties in carbon and low alloy pressure vessel steels. sponsored by the pressure vessel research committee

of the welding research council, WRC bulletin 231.52

53

EFFECT OF ALLOYING ELEMENT IN STEEL .[53]Carbon (C): Carbon is an element whose presence is imperative in all steel. Indeed, carbon is theprinciple hardening element of steel. That is, this alloying element determines the level of hardness or strength that can

be attained by quenching. Furthermore, carbon is essential for the formation ofcementite (as well as other carbides) and of pearlite, spheridite, bainite, and iron-carbon martensite, with martensite being the hardest of the microstructures.

Carbon is also responsible for increase in tensile strength, hardness, resistance towear and abrasion.

However, when present in high quantities it affects the ductility, the toughness andthe machinability of steel.

They are described as follows:Low Carbon: Under 0.4 percent Medium Carbon: 0.4 - 0.6 percent High Carbon: 0.7 - 1.5

percent Carbon is the single most important alloying element in steel.

EFFECT OF ALLOYING ELEMENT IN STEEL .[53]Carbon (C): Carbon is an element whose presence is imperative in all steel. Indeed, carbon is theprinciple hardening element of steel. That is, this alloying element determines the level of hardness or strength that can

be attained by quenching. Furthermore, carbon is essential for the formation ofcementite (as well as other carbides) and of pearlite, spheridite, bainite, and iron-carbon martensite, with martensite being the hardest of the microstructures.

Carbon is also responsible for increase in tensile strength, hardness, resistance towear and abrasion.

However, when present in high quantities it affects the ductility, the toughness andthe machinability of steel.

They are described as follows:Low Carbon: Under 0.4 percent Medium Carbon: 0.4 - 0.6 percent High Carbon: 0.7 - 1.5

percent Carbon is the single most important alloying element in steel.

54

Manganese (Mn):Increases the strength, shock resistance, toughness, hardenability, weldebility, hotformability, no change in ductility. In addition Mn is a strong austenite former by reducing the eutectoid temperaturebelow to room temperature.Manganese slightly increases the strength of ferrite, and also increases the hardnesspenetration of steel in the quench by decreasing the critical quenching speed. This alsomakes the steel more stable in the quench.

Sulfur (S):The excess sulfur reduces the ability for hot (900C) deformation of steel forming thebrittle FeS phase at the grain boundaries (hot brittleness).

The solubility of S is higher than C therefore it restricts the formation of pearlite in thezones with higher S contents, leading a banded structure of pearlite and ferrite.(Macroscopy experiment: flow lines). This causes severe anisotropy in the mechanicalprop of steel therefore S content is limited 0.035%.

However, 0.3% S may be added to free cutting steels to increase the chip formationthus the machinability

55

Manganese (Mn):Increases the strength, shock resistance, toughness, hardenability, weldebility, hotformability, no change in ductility. In addition Mn is a strong austenite former by reducing the eutectoid temperaturebelow to room temperature.Manganese slightly increases the strength of ferrite, and also increases the hardnesspenetration of steel in the quench by decreasing the critical quenching speed. This alsomakes the steel more stable in the quench.

Sulfur (S):The excess sulfur reduces the ability for hot (900C) deformation of steel forming thebrittle FeS phase at the grain boundaries (hot brittleness).

The solubility of S is higher than C therefore it restricts the formation of pearlite in thezones with higher S contents, leading a banded structure of pearlite and ferrite.(Macroscopy experiment: flow lines). This causes severe anisotropy in the mechanicalprop of steel therefore S content is limited 0.035%.

However, 0.3% S may be added to free cutting steels to increase the chip formationthus the machinability

Silicone (Si): Silicon is used as a deoxidizer in the manufacture of steel. It slightly increases the strength of ferrite, and when used in conjunction with other

alloys can help increase the toughness and hardness penetration of steel. It increases strength, decreases the weldability, magnetic losses, oxide formation

affinity, no change in ductility. In addition Si has higher affinity to O than carbon therefore used as deoxizing agent

(semi-killed steels). It is also austenite former agent leading the nucleation of austenite grain in many

size yielding finer grain size.Copper (Cu):

Copper The addition of copper in amounts of 0.2 to 0.5 percent primarily improvessteels resistance to atmospheric corrosion. It should be noted that with respect toknife steels, copper has a detrimental effect to surface quality and to hot-workingbehavior due to migration into the grain boundaries of the steel.

Copper (Cu): restricted to max. 0.35%. Up to 0.2 % provides some resistanceagainst to atmospheric corrosion. Not desired in spring steels.

Silicone (Si): Silicon is used as a deoxidizer in the manufacture of steel. It slightly increases the strength of ferrite, and when used in conjunction with other

alloys can help increase the toughness and hardness penetration of steel. It increases strength, decreases the weldability, magnetic losses, oxide formation

affinity, no change in ductility. In addition Si has higher affinity to O than carbon therefore used as deoxizing agent

(semi-killed steels). It is also austenite former agent leading the nucleation of austenite grain in many

size yielding finer grain size.Copper (Cu):

Copper The addition of copper in amounts of 0.2 to 0.5 percent primarily improvessteels resistance to atmospheric corrosion. It should be noted that with respect toknife steels, copper has a detrimental effect to surface quality and to hot-workingbehavior due to migration into the grain boundaries of the steel.

Copper (Cu): restricted to max. 0.35%. Up to 0.2 % provides some resistanceagainst to atmospheric corrosion. Not desired in spring steels.

56

Chromium (Cr): As the Cr content increases, strength, hardenability, corrosion resistance, high

temperature strength, decreases the oxide formation tendency. (forms a verycoherent oxide layer on the surface preventing further oxidation-- in stainlesssteels).

It is also strong carbide former as an essential factor behaving as a strong secondphase particle, therefore, obstructs the dislocation motion particularly at elevatedtemperatures. Also nitride former and used in nitriding steels.

Chromium As with manganese, chromium has a tendency to increase hardnesspenetration. This element has many interesting effects on steel.

Phosphorus It increases strength and hardness and decreases ductility and notch impact

toughness of steel. The adverse effects on ductility and toughness are greater in quenched and

tempered higher-carbon steels.

Nickel Nickel is a ferrite strengthener. Nickel does not form carbides in steel. It remains

in solution in ferrite, strengthening and toughening the ferrite phase. Nickelincreases the harden ability and impact strength of steels.

Chromium (Cr): As the Cr content increases, strength, hardenability, corrosion resistance, high

temperature strength, decreases the oxide formation tendency. (forms a verycoherent oxide layer on the surface preventing further oxidation-- in stainlesssteels).

It is also strong carbide former as an essential factor behaving as a strong secondphase particle, therefore, obstructs the dislocation motion particularly at elevatedtemperatures. Also nitride former and used in nitriding steels.

Chromium As with manganese, chromium has a tendency to increase hardnesspenetration. This element has many interesting effects on steel.

Phosphorus It increases strength and hardness and decreases ductility and notch impact

toughness of steel. The adverse effects on ductility and toughness are greater in quenched and

tempered higher-carbon steels.

Nickel Nickel is a ferrite strengthener. Nickel does not form carbides in steel. It remains

in solution in ferrite, strengthening and toughening the ferrite phase. Nickelincreases the harden ability and impact strength of steels.

57

The Iron-Iron Carbide Diagram A map of the temperature at which different phase changes occur on very

slow heating and cooling in relation to Carbon, is called Iron- CarbonDiagram.

Iron- Carbon diagram shows the type of alloys formed under very slow cooling, proper heat-treatment temperature and how the properties of steels and cast irons can be radically changed

by heat-treatment. Plain carbon steels are generally defined as being those alloys of iron

and carbon which contain up to 2.0% carbon The pure metal Iron, at temperatures below 910C, has a

body-centred cubic structure, and if we heat it to above thistemperature the structure will change to one which is face centredcubic.

A map of the temperature at which different phase changes occur on veryslow heating and cooling in relation to Carbon, is called Iron- CarbonDiagram.

Iron- Carbon diagram shows the type of alloys formed under very slow cooling, proper heat-treatment temperature and how the properties of steels and cast irons can be radically changed

by heat-treatment. Plain carbon steels are generally defined as being those alloys of iron

and carbon which contain up to 2.0% carbon The pure metal Iron, at temperatures below 910C, has a

body-centred cubic structure, and if we heat it to above thistemperature the structure will change to one which is face centredcubic.

IRON IRON-CARBON DIAGRAM

Austenite

Pearlite andCementine

Eutecticeutectoid

Ferrite

Steel Cast iron

Pearlite

Pearlite andCarbide

The Iron-Iron Carbide Diagram

The diagram shows three horizontal lines which indicate isothermal reactions (oncooling / heating):

First horizontal line is at 1490C, where peritectic reaction takes place:Liquid + austenite

Second horizontal line is at 1130C, where eutectic reaction takes place:liquid austenite + cementite

Third horizontal line is at 723C, where eutectoid reaction takes place:austenite pearlite (mixture of ferrite & cementite).

The diagram shows three horizontal lines which indicate isothermal reactions (oncooling / heating):

First horizontal line is at 1490C, where peritectic reaction takes place:Liquid + austenite

Second horizontal line is at 1130C, where eutectic reaction takes place:liquid austenite + cementite

Third horizontal line is at 723C, where eutectoid reaction takes place:austenite pearlite (mixture of ferrite & cementite).

61

The solid solution formed when carbon atoms are absorbed into the face-centred cubicstructure of iron is called Austenite and the extremely low level of solid solution formedwhen carbon dissolves in body-centred cubic iron is called Ferrite.

For many practical purposes we can regard ferrite as having the same properties as pureiron.the symbol ('gamma') is used to denote both the face-centred cubic form of iron and thesolid solution austenite, whilst the symbol ('alpha') is used to denote both thebody-centred cubic form of iron existing below 910C and the solid-solution ferrite

62

Definition of structures

Ferrite is known as solid solution. It is an interstitial solid solution of a small amount of carbon dissolved

in (BCC) iron. stable form of iron below 912 deg.C The maximum solubility is 0.025 % C at 723C and it dissolves only

0.008 % C at room temperature. It is the softest structure that appears on the diagram.

Ferrite is known as solid solution. It is an interstitial solid solution of a small amount of carbon dissolved

in (BCC) iron. stable form of iron below 912 deg.C The maximum solubility is 0.025 % C at 723C and it dissolves only

0.008 % C at room temperature. It is the softest structure that appears on the diagram.

Definition of structures

Pearlite is the eutectoid mixture containing 0.80% C and is formed at 723C on very slow cooling.

It is a very fine platelike or lamellar mixture offerrite and cementite.

The white ferritic background or matrix containsthin plates of cementite (dark).

64

Pearlite is the eutectoid mixture containing 0.80% C and is formed at 723C on very slow cooling.

It is a very fine platelike or lamellar mixture offerrite and cementite.

The white ferritic background or matrix containsthin plates of cementite (dark).

Austenite is an interstitial solid solution of Carbon dissolved in (F.C.C.) iron.Maximum solubility is 2.0 % C at 1130C.High formability, most of heat treatments begin with this single phase.It is normally not stable at room temperature. But, under certain conditions it is possibleto obtain austenite at room temperature.

Cementite or iron carbide, is very hard, brittle intermetalliccompound of iron & carbon, as Fe3C, contains 6.67 % C.It is the hardest structure that appears on the diagram,exact melting point unknown.Its crystal structure is orthorhombic. It is haslow tensile strength (approx. 5,000 psi), buthigh compressive strength.

65

Cementite or iron carbide, is very hard, brittle intermetalliccompound of iron & carbon, as Fe3C, contains 6.67 % C.It is the hardest structure that appears on the diagram,exact melting point unknown.Its crystal structure is orthorhombic. It is haslow tensile strength (approx. 5,000 psi), buthigh compressive strength.

Martensite - a super-saturated solid solution of carbon in ferrite.It is formed when steel is cooled so rapidly that the change from austenite to pearlite issuppressed.The interstitial carbon atoms distort the BCC ferrite into a BC-tetragonal structure(BCT).; responsible for the hardness of quenched steel.

Principal phases of steel and their Characteristics

Phase Crystal structure Characteristics

Ferrite BCC Soft, ductile, magnetic

Austenite FCC Soft, moderate strength,non-magnetic

Cementite Compound of Iron &Carbon Fe3CHard &brittleCementite Compound of Iron &Carbon Fe3CHard &brittle

Hypo-eutectoid steels: Steels having less than 0.8% carbon are called hypo-eutectoid steels (hypo means "less than").

Hyper-eutectoid steels (hyper means "greater than") are those that contain morethan the eutectoid amount of Carbon.

In arc welding, energy is transferred from the welding electrode to the basemetal by an electric arc.Heat input is a relative measure of the energy transferred per unit length ofweld.It is an important characteristic because, like preheat and interpass temperature,it influences the cooling rate, which may affect the mechanical properties andmetallurgical structure of the weld and the HAZ (see Figure 1). Heat input is typically calculated as the ratio of the power (i.e., voltage xcurrent) to the velocity of the heat source (i.e., the arc) as follows:

Cooling Rate is a Function of Heat Input

67

In arc welding, energy is transferred from the welding electrode to the basemetal by an electric arc.Heat input is a relative measure of the energy transferred per unit length ofweld.It is an important characteristic because, like preheat and interpass temperature,it influences the cooling rate, which may affect the mechanical properties andmetallurgical structure of the weld and the HAZ (see Figure 1). Heat input is typically calculated as the ratio of the power (i.e., voltage xcurrent) to the velocity of the heat source (i.e., the arc) as follows:

H = heat input (kJ/in or kJ/mm)E = arc voltage (volts)I = current (amps)S = travel speed (in/min or mm/min)

The effect of heat input on cooling rate is similar to that of the preheattemperature.As either the heat input or the preheat temperature increases, the rate of coolingdecreases for a given base metal thickness.

These two variables interact with others such as material thickness, specificheat, density, and thermal conductivity to influence the cooling rate.

The following proportionality function shows this relationship between preheattemperature, heat input and cooling rate:

68

The effect of heat input on cooling rate is similar to that of the preheattemperature.As either the heat input or the preheat temperature increases, the rate of coolingdecreases for a given base metal thickness.

These two variables interact with others such as material thickness, specificheat, density, and thermal conductivity to influence the cooling rate.

The following proportionality function shows this relationship between preheattemperature, heat input and cooling rate:

R = cooling rate (F/sec or C/sec)To = preheat temperature (F or C)H = heat input (kJ/in or kJ/mm)

69

The cooling rate is a primary factor that determines the final metallurgical structure of theweld and heat affected zone (HAZ), and is especially important with heat-treated steels.

When welding quenched and tempered steels, for example, slow cooling rates (resultingfrom high heat inputs) can soften the material adjacent to the weld, reducing the load-carrying capacity of the connection.