EFFECT OF TYPE AND CHARACTER OF QUENCHING MEDIUM ON HARDNESS OF STEEL THROUGH HEAT TREATMENT

ROS SURIAYATI BT MUSA

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

EFFECT OF TYPE AND CHARACTER OF QUENCHING MEDUIM ON

HARDNESS OF STEEL THROUGH HEAT TREATMENT

ROS SURIAYATI BT MUSA

This thesis is submitted to Faculty of Mechanical Engineering as Partial Fulfillment

of Requirement for Award of the Degree of Bachelor of Mechanical Engineering

(Structure & Material)

Faculty of Mechanical Engineering

Universiti Teknikal Malaysia Melaka

November 2008

“I declare that I have already read this thesis entitle effect of type & character of

quenching medium on hardness of steel through heat treatment and the point of my view

that this report is qualify for this scope & quality to fulfill the award for Bachelor

Degree of Mechanical Engineering (Structure & Material)”

Signature : …………………………………………

Name : …………………………………………

Date : ……………………………

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“ I hereby declare that this project report is written by me and it is my own effort and

that no part has been plagiarized without citations”

Signature :……………………………….....

Name of Writer :……………………………….…

Date :………………………………….

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To my lovely parents, brothers and sisters, my supervisors and all my friends

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ACKNOWLEDGEMENT

First and foremost, ALHAMDULILLAH I am grateful to ALLAH SWT on His

blessing in completing this project. I am also thankful to Him because through my

studying at Universiti Teknikal Malaysia Melaka (UTeM), it is easier for me to get

knowledgement by Him and all resistances and obstacles is faced can be resolved with

diligent and patiently.

I would like to take this opportunity to thanks my project supervisor, Puan

Zakiah bt Abd Halim for her invaluable guidance, assistance and support throughout this

research. Under her supervision, many aspects regarding on this project has been

explored, and with knowledge, idea and support received from her, this thesis can be

represented in the given time.

Not forget I wish to acknowledge the technicians especially Materials Science

and Technology Lab’s technician, En Mahader for his help and assistance on the

experiment during finishing this thesis. Without his guidance maybe this project cannot

be completed succesfully.

Finally, I would like to dedicate my gratitude to all my lectures involved and

teaching my course, thanks for the lesson that been delivered. Not forget to my lovely

parents, Encik Musa bin Ngah and Semek@Aishah bt Awang and also all my friends.

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ABSTRAK

Kajian ini dijalankan menggunakan keluli karbon sederhana, AISI 1040. Melalui

prosess rawatan haba, tesis ini menyiasat tentang kesan kekerasan pada jenis dan

karakteristik medium penyejukan. Objektif utama kajian ini dilakukan adalah untuk

meningkatkan mutu ekperimen rawatan haba yang telah sedia ada untuk subjek Sains

Bahan dan bertujuan untuk menyediakan satu set baru eksperimen yang lebih efisyen

dan berjaya. Set ini hanya untuk eksperimen yang fokus pada jenis-jenis dan karakter

medium penyejukan tersebut. Tesis ini meliputi proses yang pertama iaitu penyediaan

bahan dari bahan mentah hinggalah kepada analisis data. Selain perbezaan jenis medium

penyejukan yang digunakan sperti minyak, air dan larutan garam, sifat-sifat medium

penyejukan ini juga di ambil kira bagaimana ia memberi kesan kepada kekerasan keluli.

Antara parameter sifat-sifat media penyejukan yang dikaji termasuklah perbezaan tahap

kocakan (kacauan), perbezaan suhu awal medium penyejukan dan perbezaan teknik

penyejukan selepas kocakan (kacauan).

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ABSTRACT

The research is carried on specimen of medium carbon steel, AISI 1040.

Through heat treatment process, the effect of type and character of quenching medium

on hardness are investigated. The main objective of this research is to improve the

existing heat treatment in Material Science subject by recommending a new set of

experiment that can successfully heat treated steels by focusing on type and character of

quenching medium. This thesis had covered from the first process, which is material

preparation until the data analysis. Beside differences in type of quenching medium used

which are oil, water and brine, the character of this quenching medium also considered

how it will give effect to steel hardness. The parameter of character that investigated in

this project includes the differences of mode of agitation, the initial quenching medium

temperature and the technique of quenching after agitation.

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TABLE OF CONTENT

CHAPTER DESCRIPTION PAGE

CONFESSION ii

DEDICATION iii

ACKNKOWLEDGEMENT iv

ABSTRAK v

ABSTRACT vi

TABLE OF CONTENT vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF APPENDIX xiii

1 INTRODUCTION

1.1 Overview 1

1.2 Problem Statement 2

1.3 Problem Identifications 3

1.4 Objectives 3

1.5 Scope 4

2 LITERATURE REVIEW

2.1 Overview 6

2.2 Studies on steel

2.2.1 Classification of steel 6

2.2.2 The hardenibility heat treatment of steel 7

2.2.3 Carbon steel 8

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2.3 Effect of section size and agitation 9

2.4 Assessment of mechanical properties 10

2.5 Heat treatment 11

2.6 Quenching Medium 13

2.6.1 Water 14

2.6.1.1 Temperature dependence 14

2.6.1.2 Vapor phase stability 15

2.6.1.3 High cooling rates in convection

phase 14 15

2.6.2 Brine 15

2.6.3 Oil 16

3 METHODOLOGY

3.1 Overview 17

3.2 Laboratory Flow Chart 17

3.3 Preparation of work piece 18

3.3.1 Raw material 18

3.3.2 Specimen preparation 19

3.4 Mark the Specimen 21

3.5 Hardness Test before heat treatment 21

3.6 Austenization/ Heating Process and Cooling 22

3.6.1 Austenization process 22

3.6.2 Heating process 23

3.6.3 Quenching process 24

3.7 Grinding and Polishing 26

3.8 Hardness test 27

3.9 Heat Treatment data 29

4 RESULTS AND DISCUSSION

4.1 Overview 33

4.2 Hardness reading before Heat Treatment 34

4.3 Hardness reading after Heat Treatment 35

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4.3.1 Effect of mode of agitation 35

4.3.2 Effect of initial quenching medium

Temperature 38

4.3.3 Effect of technique of quenching after

Agitation 41

4.4 The other character of Quenching medium

4.4.1 Mass effect 43

4.4.2 The volume of Quenching medium 44

5 CONCLUSION AND RECOMMENDATION

5.1 Overview 45

5.2 Conclusion 45

5.3 Recommendation 46

REFERENCES 48

APPENDIX A 50

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LIST OF TABLE

NO. TITLE PAGE

2.1 Composition of Carbon Steel 8

2.2 Properties and Average Cooling Abilities of Quenching Media 16

3.1 Composition of AISI 1040 steel specime

(Source: P.Fernandes, K.N Prabhu/ Journal of Materials Processing

Technology 183 (2007) 1-5) 19

3.2 Specification of Band Saw Machine 21

3.3 Specification of LT Furnace 26

3.4 Specification of Hardness Tester 29

3.5 To study the effect of Agitation 30

3.6 To study the effect of initial quenching medium temperature

(mode of agitation still) 30

3.7 To study the effect of initial quenching medium temperature

(mode of agitation moderate) 31

3.8 To study the effect of initial quenching medium temperature

(mode of agitation rough) 31

3.9 To study the effect of technique of quenching after agitation 32

4.1 Effect of mode of Agitation 36

4.2 Effect of initial quenching medium temperature (mode of agitation still) 38

4.3 Effect of initial quenching medium temperature

(mode of agitation moderate) 39

4.4 Effect of initial quenching medium temperature (mode of agitation rough) 39

4.5 Effect of technique of quenching after agitation 43

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LIST OF FIGURE

NO. TITLE PAGE

2.1 The Eutectoid transformation between austenite (γ) and pearlite

(source: Muldrew, Ken; Locksley E. McGann (1997) 12

3.1 Laboratory Flow Chart 18

3.2 Specimen dimension 20

3.3 Band saw machine 20

3.4 Specimens cut from raw material 20

3.5 Steel phase diagram

(Source: Christophe Dang Ngoc Chan1998) 23

3.6 Electric Furnace and LT Furnace 24

3.7 Using safety tool to place the specimen into furnace 24

3.8 Three types of quenching medium 25

3.9 Manual Grinding Machine 26

3.10 Polishing Machine 27

3.11 Hardness test on longitudinal direction 28

3.12 Location of hardness’s points (center and surface) 29

4.1 Schematic illustration of Heat Treatment process 34

4.2 Comparison on hardness of type and character of quenching medium 36

4.3 Effect of initial quenching temperature on hardness based on mode of

agitation during quenching in oil. 40

4.4 Effect of initial quenching temperature on hardness based on mode of

agitation during quenching in water. 40

4.5 Effect of initial quenching temperature on hardness based on mode of

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agitation during quenching in Brine. 41

4.6 Effect of technique of quenching after agitation on hardness based on

quenching medium 42

xiii

LIST OF APPENDIX

NO. TITLE PAGE

1 APPENDIX A

( Hardness of specimen before Heat Treatment process)

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CHAPTER 1

INTRODUCTION

3.10Overview

University Teknikal Malaysia Melaka’s (UTeM) student especially second year

students from Faculty of Mechanical are studying Science Material as a core subject.

Heat treatment of steel is one of the experiments that carried out in this subject. This

research is about the types and character of quenching medium affects the hardness of

steel through heat treatment.

Heat treatment of steels is a heat-treating process whereby the steel are exposed

to an elevated temperature for a period time and cooled of which transforms or changes

the mechanical properties without changing the specimen shape. Heat treatment can be

define as an operation or set of operations in a metal involving heating and controlled

cooling. Transformation in the solid state can be obtained using heat treatment

procedures, which cause changes in microstructure resulting in materials with a wide

range of hardness and mechanical properties. Although an exact relationship between

hardness and wear performance does not exist, hardness has traditionally been the

properly used for quality control, selection of steel, and heat treatment and performance

evaluation (Totten. G.E. and Liang. H, 2004).

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Quenching is one of the important processes of the heat treatment to improve the

performance of steel. During quenching, the steel is rapidly cooled in a quenching

medium from the austenitising temperature typically in the range 845-870 ºC.

Quenching is performed to prevent ferrite or pearlite formation and allow bainite or

martensite to be formed. The selection of a quenching medium depends on the

hardenability of particular alloy, the section thickness and shape involved, and the

cooling rates needed to achieve desired microstructure. The most common quenching

media used include oil that may contain a variety of additives, water, aqueous polymer

solution and water may contain salt or caustic additives.

As can know, steels are among the most important engineering materials because

without them, the machinery and tools are required to establish any industrial activity

would be difficult to imagine. A very important property of steel is the ability to alter its

hardness by simple heat treatments. Carbon steel can be classified according to various

deoxidation process. Deoxidation practice and steelmaking process will have an effect

on the characteristics and properties of the steel. Generally, carbon steels contain up to

2% total alloying elements and can be subdivided into low-carbon,medium-carbon,

high-carbon, and ultrahigh-carbon (UHC) steels.

3.11Problem statement

Heat treatment of steel is already done in laboratory session for Material Science

subject by students. The existing heat treatment experiment focus on the study of effects

of different quenching medium but at the same austenization temperature and soaking

time. The other problems are from the research, it is noted that usually the existing heat

treatment experiment almost take more than lab session hour, which is usually three

hours. But usually extend until a few hours and give effect for the others session.

Besides that, the material used for this project different with the exits material in heat

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treatment experiment. Cause of that, study on the type of these material properties, and

also for different type and characteristic of quenching medium is needed.

3.12Problem Identifications

In order to study the effect of type and character of quenching medium to

specimen properties, the different types of mediums used which are oil, water and brine.

Different quench character such as agitation mode, initial temperature of quenching

medium and the technique of quenching after agitation are raised.

To make sure the three hours lab session is enough for heat treatment experiment,

a new set experiment as these parameters affect the hardness of specimen will be

recommended. In order to achieve the objective, medium carbon steel is used as

specimen as replacement to plain carbon steel that already used in heat treatment

experiment. To measure the hardenability of the specimen, the Brinell Hardness Test is

suitable to use.

1.4 Objectives

For any research, the objective is the main element that must have. So, in this

research, the main objectives are to improve the existing heat treatment experiment in

Material Science subject at Univesity Technical Malaysia Melaka (UTeM). Medium-

carbon steel is used as specimen as already in the experiment. A new set of heat teatment

experiment will be recommended after all analysis is done. This will be take new set of

heat experiment with update procedure and steps that can successfully heat treated

steels.

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AISI-SAE 1040 Plain Carbon Steel is used in this experiment which is in

standard size and shape; diameter and thickness. The specimen used is ∅20mm in

diameter and 10mm thickness in cylinder shape. Not same as previously heat treatment

in Material Science subject, which have use AISI-SAE 1080 Plain Carbon Steel for the

experiment as specimen.

The other objective in this research is to focus on type and character of

quenching medium. Quenching medium use in this experiment are brine, water, and oil.

This research wills analysis the type of these media that will give effect to the specimen

and also the character of it. The size, composition and initial temperature of the

specimen and the final properties are deciding factors in selecting the quenching

medium. All parameter will be considered in this analysis.

1.5 Scope

The main scope in this project are handling and conducting the experiment using

all heat treatment equipments in Materials Science and Technology Lab at UTeM. The

specimen comes as raw material in a roll of steel with 1 meter long. The steel is cut

properly with bandsaw machine as 15mm each. After that, using CNC machine, the

specimen machined to get 10mm thickness. The gas furnace is use for heat treatment

process. After quenching process, all specimens are grinded and polished before tested

the hardness using Brinell Hardnes Test.

As previously, it was state that the plain carbon AISI 1040 is the material used

compared to existing heat treatment using AISI 1080. The standard specimen for this

experiment is in round shape with dimension 20 mm and 10 mm length.

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Based on cost effectiveness, it refers to power consumption requirements. For

example the heating process by Gas Furnace, how much lot of the power (kilowatt per

hour) used to heat the specimen for a period of time.

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CHAPTER 2

LITERATURE REVIEW

2.1 Overview

Chapter 2 discusses about studies on steel, classification of steel through its

composition, the review of past research by others scientist and also the assessment of

mechanical properties.

2.2 Studies on steel

2.2.1 Classification of steel

According to Anil Kumar Sinha et.al (2006), steel can be classified by different

systems depending on:

1 Compositions, such as carbon (or nonalloy), low-alloy, and alloy steel

2 Manufacturing methods, such as converter, electric furnace, or

elecrtroslag remelting method

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3 Application or main characteristic, such as structural, tool, stainless

steel or heat-resistant steels

4 Finishing methods such as hot rolling, cold rolling, casting, or

controlled rolling and controlled cooling

5 Product shape, such as bar, plate, strip, tubing, or structural shape

6 Oxidation practice employed, such as rimmed, killed, semikilled, and

chapped steels

7 Microstructure, such as ferritic, pearlitic, martensitic, and austenitic

8 Required strength level, as specified in the American Society for

Testing and Materials (ASTM) standards

9 Heat treatment, such as annealing, quenching and tempering, air

cooling (normalization), and thermo mechanical processing

10 Quality descriptors and classifications, such as forging quality and

commercial quality

Steels are commonly made from iron ore, coal, and limestone. When these raw

materials are put into the blast furnace, the result is a pig iron which has a composition

of iron, carbon, manganese, sulfur, phosphorus, and silicon. As pig iron is hard and

brittle, steelmakers must refine the material by purifying it and then adding other

elements to strengthen the material. The steel is next deoxidized by a carbon and oxygen

reaction.

2.2.2 The hardenibility heat treatment of steel

Bhadeshia and Robert Honeycombe (2006), introduced the traditional route to

high strength in steels is by quenching to form martensite which is subsequently

reheated or tempered at an intermediate temperature, increasing the toughness of the

steel without too great a loss in strength. Therefore, for optimum development of

strength, a steel must first be fully converted to martensite. To achive this situation, the

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steel must be quenched at a rate sufficiently rapid to avoid the decomposition of

austenite during cooling to such products as ferrite, pearlite and bainite. The

effectiveness of the quench will depend primarily on two factors; the geometry of the

specimen, and the composition of the steel.

2.2.3 Carbon Steel

According to Efunda Engineering Fundamentals, carbon steels are steels whose

alloying elements do not exceed the following limits:

Table 2.1 : Composition of Carbon Steel

(http://www.efunda.eng.com)

Element Max weight (%)C 1.00Cu 0.60Mn 1.65P 0.40Si 0.60S 0.005

Wikipedia mentioned that Carbon steel also called plain carbon steel, is a metal

alloy, a combination of two elements, iron and carbon, where other elements are present

in quantities too small to affect the properties. The only other alloying elements allowed

in plain-carbon steel are manganese (1.65% max), silicon (0.60% max), and copper

(0.60% max). As general, Carbon steel classified to three groups, which are Mild or Low

carbon steel, Medium carbon steel and High Carbon steel. Low carbon steel has

approximately 0.05% to 0.29% carbon content. Steel with low carbon content has the

same properties as iron, soft but easily formed. Besides that, it has low tensile strength,

but it is cheap and malleable, and surface hardness can be increased through carburizing.