Effect Of Type And Character Of Quenching Medium On Hardness Of Steel Through Heat Treatment.
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
: ……………………………
ii
“ 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
:………………………………….
iii
To my lovely parents, brothers and sisters, my supervisors and all my friends
iv
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.
v
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).
vi
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.
vii
TABLE OF CONTENT
CHAPTER
1
DESCRIPTION
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
INTRODUCTION
1.1
2
PAGE
Overview
1
1.2 Problem Statement
2
1.3
Problem Identifications
3
1.4
Objectives
3
1.5
Scope
4
LITERATURE REVIEW
2.1
Overview
2.2
Studies on steel
6
2.2.1
Classification of steel
6
2.2.2
The hardenibility heat treatment of steel
7
2.2.3
Carbon steel
8
viii
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
3
4
15
2.6.2
Brine
15
2.6.3
Oil
16
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
19
Specimen preparation
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
RESULTS AND DISCUSSION
4.1
Overview
33
4.2
Hardness reading before Heat Treatment
34
4.3
Hardness reading after Heat Treatment
35
ix
4.3.1
Effect of mode of agitation
4.3.2
Effect of initial quenching medium
Temperature
4.3.3
5
38
Effect of technique of quenching after
Agitation
4.4
35
41
The other character of Quenching medium
4.4.1
Mass effect
43
4.4.2
The volume of Quenching medium
44
CONCLUSION AND RECOMMENDATION
5.1
Overview
45
5.2
Conclusion
45
5.3
Recommendation
46
REFERENCES
48
APPENDIX A
50
x
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)
3.7
To study the effect of initial quenching medium temperature
(mode of agitation moderate)
3.8
30
31
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
xi
LIST OF FIGURE
NO.
2.1
TITLE
PAGE
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.
4.4
Effect of initial quenching temperature on hardness based on mode of
agitation during quenching in water.
4.5
40
Effect of initial quenching temperature on hardness based on mode of
40
xii
agitation during quenching in Brine.
4.6
41
Effect of technique of quenching after agitation on hardness based on
quenching medium
42
xiii
LIST OF APPENDIX
NO.
1
TITLE
APPENDIX A
( Hardness of specimen before Heat Treatment process)
PAGE
1
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).
2
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
3
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). Mediumcarbon 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.
4
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.
5
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.
6
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
7
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
8
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
C
Cu
Mn
P
Si
S
Max weight (%)
1.00
0.60
1.65
0.40
0.60
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.
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
: ……………………………
ii
“ 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
:………………………………….
iii
To my lovely parents, brothers and sisters, my supervisors and all my friends
iv
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.
v
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).
vi
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.
vii
TABLE OF CONTENT
CHAPTER
1
DESCRIPTION
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
INTRODUCTION
1.1
2
PAGE
Overview
1
1.2 Problem Statement
2
1.3
Problem Identifications
3
1.4
Objectives
3
1.5
Scope
4
LITERATURE REVIEW
2.1
Overview
2.2
Studies on steel
6
2.2.1
Classification of steel
6
2.2.2
The hardenibility heat treatment of steel
7
2.2.3
Carbon steel
8
viii
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
3
4
15
2.6.2
Brine
15
2.6.3
Oil
16
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
19
Specimen preparation
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
RESULTS AND DISCUSSION
4.1
Overview
33
4.2
Hardness reading before Heat Treatment
34
4.3
Hardness reading after Heat Treatment
35
ix
4.3.1
Effect of mode of agitation
4.3.2
Effect of initial quenching medium
Temperature
4.3.3
5
38
Effect of technique of quenching after
Agitation
4.4
35
41
The other character of Quenching medium
4.4.1
Mass effect
43
4.4.2
The volume of Quenching medium
44
CONCLUSION AND RECOMMENDATION
5.1
Overview
45
5.2
Conclusion
45
5.3
Recommendation
46
REFERENCES
48
APPENDIX A
50
x
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)
3.7
To study the effect of initial quenching medium temperature
(mode of agitation moderate)
3.8
30
31
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
xi
LIST OF FIGURE
NO.
2.1
TITLE
PAGE
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.
4.4
Effect of initial quenching temperature on hardness based on mode of
agitation during quenching in water.
4.5
40
Effect of initial quenching temperature on hardness based on mode of
40
xii
agitation during quenching in Brine.
4.6
41
Effect of technique of quenching after agitation on hardness based on
quenching medium
42
xiii
LIST OF APPENDIX
NO.
1
TITLE
APPENDIX A
( Hardness of specimen before Heat Treatment process)
PAGE
1
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).
2
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
3
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). Mediumcarbon 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.
4
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.
5
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.
6
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
7
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
8
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
C
Cu
Mn
P
Si
S
Max weight (%)
1.00
0.60
1.65
0.40
0.60
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.