THE MECHANICAL BEHAVIORS OF SHIELD-ED BY MUHAMMAD …

THE MECHANICAL BEHAVIORS OF SHIELD-ED

METAL ARC WELDING (SMAW) OF BUTT JOINT OF

MILD STEEL

BY

MUHAMMAD SAIFUL ADLI BIN FOUZI

A dissertation submitted in fulfilment of requirement for the

degree of Master of Science (Manufacturing Engineering)

Kulliyyah of Engineering

International Islamic University Malaysia

JUNE 2016

ii

ABSTRACT

Mechanical behaviours/properties are the most important engineering considerations

in manufacturing, design, and constructions of products. These manufacturing usually

involve assembling and joining of the components and parts to form a complete

product. One of the widely used metal joining method is fusion welding method. In

this study, mechanical behaviours of Shielded Metal Arc Welding (SMAW) of mild

steel were studied. Welding works were performed using current, voltage and polarity

parameters. Investigations of tensile testing, impact testing, hardness testing, and

microstructure examination of welded mild steel have been conducted. The relation

between ultimate tensile strength (UTS) and current shows a fluctuation pattern.

Increasing current does not increase UTS proportionally. UTS also does not

proportional with voltage. Furthermore, for correlation of UTS and current relative to

polarity, the UTS for DCEN polarity were observed to be higher than UTS for DCEP

polarity. For voltage from 23 to 24 volts, the UTS for DCEN polarity were higher than

the UTS for DCEP polarity. However, as the voltage increase from 26 to 27 volts, the

UTS for DCEP polarity eventually become higher than the UTS for DCEN polarity. In

order to achieve high UTS and tensile strength, one should choose current from 68 to

120 ampere combined with voltage of 23 volts. For maximum toughness, high current

ranged from 102 amperes to 120 amperes should be used with voltage varied from 24

to 26 volts in DCEN polarity. The microstructure of the weld metal shows a

combination of ferrite and pearlite grain structure which signifies that the welded

materials exhibit in brittle and ductile behaviors correspondingly. Three positions of

indentation were used to measure the hardness of the welded materials which are

fusion zone, heat affected zone (HAZ) and base metal zone. Among those three, the

hardness properties at the fusion zone are the highest for most samples tested. The

hardness was also observed to be highest when the current is 70 amperes. The

hardness was found to be directly proportional to the voltage values.

iii

البحث ملخصABSTRACT IN ARABIC

خواص المعدن وسلوكه الميكانيكي تعتبر من اهم الاعتبارات الهندسية خلال التصنيع و التصميم وتجهيز المنتجات. عمليات التصنيع عادة تشمل التجميع و التوصيل للمكونات مع

ل المنتج النهائي. احدى الاستخدامات الشائعة لطرق توصيل المعادن هي بعض لتشكياسلوب اللحام بالانصهار. في هذه البحث, تم دراسة السلوك الميكانيكي للفولاذ الطري بعد

( . تم تنفيذ اعمال اللحام باستخدام التيار و الفولتية و SMAWلحامه بطريقة القوس المحمي )التحقيقات عن طريق اختبار الشد و اختبار الصدم و اختبار الصلادة القطبية. وقد تم اجراء

و الفحص المجهري لعينات الفولاذ الطري الملحوم. وقد بينت النتائج ان العلاقة بين قوة الشد ( والتيار اظهرت نمط متذبذب, وان زيادة التيار لاتزيد من قوة الشد UTSالقصوى )والتيار UTSلفولتية. وعلاوة على ذلك, العلاقة بين ايضاً لاتتناسب مع ا UTSالقصوى.

. DCEPلقطبية UTSكانت اعلى من DCENلقطبية UTSبالنسبة للقطبية, لوحظ ان UTSاعلى من DCENلقطبية UTSفولت, كانت 32الى 32وبالنسبة للفولتية من

في نهاية المطاف فولت, تصبح 32الى 32. ومع ذلك, بزيادة الفولتية من DCEPلقطبية UTS لقطبيةDCEP اعلى منUTS لقطبيةDCEN وبهدف تحقيق اعلى .UTS و قوة

فولت. 32امبير الى جانب الفولتية بقيمة 031الى 26الشد, ينبغي اختيار تيار من امبير يجب ان تستخدم مع 031الى 013وللحصول على اعلى متانة, قيم تيار عالية من

. واظهرت البُنى المجهرية للمعادن الملحومة DCENفولت خلال قطبية 32الى 32فولتية من . وتم قياس الصلادة في ثلاثة مواضع مختلفة pearliteو الـ ferriteات الـ مزيج من حبيب

( والمعدن الاساسي, HAZللمعادن الملحومة وهي منطقة الانصهار والمنطقة المتأثرة بالحرارة )ومن خلال ذلك تبين ان الصلادة في منطقة الانصهار هي الاعلى بالنسبة لمعظم العينات

21لوحظ ايضاً ان الصلادة كانت عالية عندما استخدم تيار بقيمة التي تم فحصها. وقد امبير, وقد وجد كذلك ان الصلادة تتناسب طردياً مع قيم الجهد.

iv

APPROVAL PAGE

I certify that I have supervised and read this study and that in my opinion; it conforms

to acceptable standards of scholarly presentation and is fully adequate, in scope and

quality, as a dissertation for the degree of Master of Science (Manufacturing

Engineering).

……………………………………..

Suryanto

Supervisor

I certify that I have read this study and that in my opinion it conforms to acceptable

standards of scholarly presentation and is fully adequate, in scope and quality, as a

dissertation for the degree of Master of Science (Manufacturing Engineering).

……………………………………..

Mohammad Iqbal

Internal Examiner

……………………………………..

Muataz Hazza Faizi Al Hazza

Internal Examiner

This dissertation was submitted to the Department of Mechatronics Engineering and is

accepted as a fulfilment of the requirement for the degree of Master of Science

(Manufacturing Engineering).

……………………………………..

Md. Yusof Ismail

Head, Advanced Engineering and

Innovation Centre

This dissertation was submitted to the Kulliyyah of Engineering and is accepted as a

fulfilment of the requirement for the degree of Master of Science (Manufacturing

Engineering).

……………………………………..

Md. Noor Bin Salleh

Dean, Kulliyyah of Engineering

v

DECLARATION

I hereby declare that this dissertation is the result of my own investigation, except

where otherwise stated. I also declare that it has not been previously or concurrently

submitted as a whole for any other degrees at IIUM or other institutions.

Muhammad Saiful Adli bin Fouzi

Signature…………………....………. Date …….……………….

vi

COPYRIGHT

INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA

DECLARATION OF COPYRIGHT AND AFFIRMATION OF

FAIR USE OF UNPUBLISHED RESEARCH

THE MECHANICAL BEHAVIORS OF SHIELD-ED METAL ARC

WELDING (SMAW) OF BUTT JOINT OF MILD STEEL

I declare that the copyright holder of this dissertation are jointly owned by the

student and IIUM.

Copyright © 2016 Muhammad Saiful Adli bin Fouzi and International Islamic University Malaysia.

All rights reserved.

No part of this unpublished research may be reproduced, stored in a retrieval system,

or transmitted, in any form or by any means, electronic, mechanical, photocopying,

recording or otherwise without prior written permission of the copyright holder

except as provided below

1. Any material contained in or derived from this unpublished research may

be used by others in their writing with due acknowledgement.

2. IIUM or its library will have the right to make and transmit copies (print

or electronic) for institutional and academic purposes.

3. The IIUM library will have the right to make, store in a retrieved system

and supply copies of this unpublished research if requested by other

universities and research libraries.

By signing this form, I acknowledged that I have read and understand the IIUM

Intellectual Property Right and Commercialization policy.

Affirmed by Muhammad Saiful Adli bin Fouzi

……..…………………….. ………………………..

Signature Date

vii

DEDICATION

This dissertation is dedicated to my beloved parents

viii

ACKNOWLEDGEMENTS

Bismillahirrahmanirrahim. By the name of Allah swt., the Most Gracious, the Most

Beneficial, Alhamdulillah, All praises to Allah swt.

Firstly, it is my utmost pleasure to dedicate this work to my dear parents and

my family, who granted me the gift of their unwavering belief in my ability to

accomplish this goal: thank you for your support and patience.

I wish to express my sincerest appreciation and thanks especially to my

colleagues in Politeknik Kota Bharu and International Islamic University Malaysia,

friends and those who provided their time, effort and support for this project. To the

members of my dissertation committee, thank you for sticking with me.

Finally, a special thanks to Associate Professor Dr. Suryanto for his

continuous support, encouragement and leadership, and for that, I will be forever

grateful.

Jazakumullahum khairan.

ix

TABLE OF CONTENTS

Abstract ........................................................................................................................ ii Abstract in Arabic ........................................................................................................ iii Approval Page .............................................................................................................. iv

Declaration ................................................................................................................... v Copyright ..................................................................................................................... vi Dedication .................................................................................................................... vii Acknowledgements ...................................................................................................... viii List of Tables ............................................................................................................... xi

List of Figures .............................................................................................................. xii List of Symbols ............................................................................................................ xv List of Abbreviations ................................................................................................... xvi

CHAPTER ONE: INTRODUCTION ..................................................................... 1 1.1 Background of the Study ............................................................................ 1 1.2 Statement of the Problem............................................................................ 3

1.3 Research Objectives.................................................................................... 4 1.4 Methodology of Research ........................................................................... 4

1.5 Research Scope ........................................................................................... 7 1.6 Organization of the Thesis .......................................................................... 8

CHAPTER TWO: LITERATURE REVIEW ........................................................ 10 2.1 Introduction................................................................................................. 10 2.2 Shielded Metal Arc Welding (SMAW) ...................................................... 10

2.2.1 Butt Joint and Mild Steel .................................................................. 13

2.3 Mexhanical Behaviors of Materials ............................................................ 14 2.3.1 Tensile Strength and Tensile Test ..................................................... 15

2.3.2 Hardness and Hardness Testing ........................................................ 17 2.3.3 Toughness and Impact Testing ......................................................... 19

2.3.4 Microstructure Examination and Analysis ........................................ 19 2.4 Summary ..................................................................................................... 22

CHAPTER THREE: EXPERIMENTAL WORKS ............................................... 24 3.1 Introduction................................................................................................. 24 3.2 Experimental Works ................................................................................... 24

3.2.1 Sample Preparation ........................................................................... 25

3.2.2 Welding Works ................................................................................. 25 3.3 Characterization of Mechanical Behaviors ................................................. 27

3.3.1 Tensile Testing .................................................................................. 27 3.3.2 Hardness Testing ............................................................................... 31 3.3.3 Impact Testing................................................................................... 33

3.3.4 Microstructure Examination ............................................................. 35 3.4 Summary ..................................................................................................... 38

CHAPTER FOUR: RESULTS AND DISCUSSIONS ........................................... 40 4.1 Introduction................................................................................................. 40

x

4.2 Welding Samples Observations .................................................................. 40

4.2.1 Sample 1 ............................................................................................ 40 4.2.2 Sample 2 ............................................................................................ 41

4.2.3 Sample 3 ............................................................................................ 41 4.2.4 Sample 4 ............................................................................................ 42 4.2.5 Sample 5 ............................................................................................ 43 4.2.6 Sample 6 ............................................................................................ 43 4.2.7 Sample 7 ............................................................................................ 44

4.2.8 Sample 8 ............................................................................................ 45 4.3 Tensile Testing Results ............................................................................... 45

4.3.1 Ultimate Tensile Strength ................................................................. 48 4.3.1.1 Effect of Welding Current on UTS ....................................... 50

4.3.1.2 Effect of Welding Voltage on UTS ...................................... 51 4.3.2 Yield Strength ................................................................................... 52

4.3.2.1 Effect of Welding Current on Yield Strength ...................... 53

4.3.2.2 Effect of Welding Voltage on Yield Strength ...................... 54 4.4 Toughness of Welded Samples ................................................................... 55

4.4.1 Effect of Welding Current on Toughness ......................................... 57 4.4.2 Effect of Welding Voltage on Toughness ......................................... 58

4.5 Hardness of Welded Samples ..................................................................... 59 4.5.1 Variation Hardness with Welding Current........................................ 61

4.5.2 Variation Hardness with Welding Voltage ....................................... 62 4.6 Microstructure Analysis ............................................................................. 63

4.6.1 Microstructure for Various Welding Current .................................... 65

4.6.2 Microstructure for Various Welding Voltage ................................... 66 4.6.3 Microstructure for Different Polarity ................................................ 67

4.7 Summary ..................................................................................................... 68

CHAPTER FIVE: CONCLUSION AND RECOMMENDATION ...................... 71 5.1 Conclusion .................................................................................................. 71 5.2 Recommendation ........................................................................................ 73

REFERENCES ........................................................................................................... 75

xi

LIST OF TABLES

Table 1.1 The chemical composition of mild steel (Jha, 2014) 8

Table 2.1 Table of comparison 21

Table 3.1 Welding sample and their parameters 26

Table 4.1 Break Stress for Each Sample 46

Table 4.2 Stress-Strain Data for Each Sample 48

Table 4.3 Hardness of Welded Steel (HRA) 59

xii

LIST OF FIGURES

Figure 1.1 Flow chart of research methodology 6

Figure 1.2 Single ‘V’ butt joint 8

Figure 2.1 SMAW process (Kalpakjian & Schmid, 2006) 12

Figure 2.2 Ilustration of single ‘V’ butt joint (Aweda et al.) 13

Figure 2.3 Standard tensile specimens (Udomphol, 2009) 16

Figure 2.4 Hardness test specimen 17

Figure 2.5 Butt welded joint with the sample locations of hardness testing

(Bodude & Momohjimoh, 2015) 18

Figure 2.6 Standard impact test specimen (Vinoth, 2015) 19

Figure 3.1 Single ‘V’ butt joint preparation (All dimensions in millimeters) 25

Figure 3.2 SMAW welding work 26

Figure 3.3 Tensile specimen (Udomphol, 2009) 28

Figure 3.4 CNC Milling AJAX/AJ340 29

Figure 3.5 Tensile specimen after machining 29

Figure 3.6 Instron Universal Testing Machine Model 5582 s/n p1646 30

Figure 3.7 Placing tensile specimen in the testing 31

Figure 3.8 Positions of the hardness testing at the SMAW welded sample 32

Figure 3.9 Mitutoyo--Series 810 ARK 600 Rockwell Hardness Tester 33

Figure 3.10 Mitsubishi EDM Wire Cut 34

Figure 3.11 Charpy V-notch specimens 34

Figure 3.12 Charpy V notch impact test specimen after machined 35

Figure 3.13 Floor Standing Impact Tester: Instron (ModelSI-1B: 120ft-lbs) 35

Figure 3.14 Manual grinding 37

Figure 3.15 Buehler phoenix beta for polishing 37

Figure 3.16 PRESI Mecapol p262 37

xiii

Figure 3.17 Optical Microscope: NIKON Epiphot 200 38

Figure 4.1 Welded mild steel using SMAW, 70 Amp, 27 V and DCEN

(Sample 1) 40


(sample 2) 41

Figure 4.3 Welded mild steel using SMAW, 68 Amp, 23 V and DCEP

(sample 3) 42


(sample 4) 42


(sample 5) 43


(sample 6) 44


(sample 7) 44


(sample 8) 45

Figure 4.9 Fractured tensile sample 46

Figure 4.10 The ultimate tensile strength of tested sample 49

Figure 4.11 UTS mild steel as a function of current for DCEN and DCEP

polarity 50

Figure 4.12 UTS of mild steel as a function of welding voltage for DCEN and

DCEP polarity 51

Figure 4.13 Yield strength of the tested sample 52

Figure 4.14 Yield Strength as a function of welding current for DCEP and

DCEN polarity 53

Figure 4.15 Yield Strength of mild steel as function of welding current for

DCEN and DCEP polarity 54

Figure 4.16 Charpy V-notch Impact Test Results 55

Figure 4.17 Examples of fractured impact test specimen 56

Figure 4.18 Toughness varies with welding current for DCEN and DCEP

polarity 57

xiv

Figure 4.19 Toughness varies with Welding Voltage for DCEN and DCEP

polarity 58

Figure 4.20 Hardness of Welded samples 60

Figure 4.21 Variation fusion zone hardness with current for DCEN and DCEP

polarity 61

Figure 4.22 Variation fusion zone hardness with welding voltage for DCEN

and DCEP polarity 62

Figure 4.23 Microstructures of weld bead at 500 × OM magnifications for

various welding samples 64


various welding current 65


various welding voltage 66

Figure 4.26 Microstructures of different polarities weld bead at 500 × OM

magnifications 68

xv

LIST OF SYMBOLS

A Area

I Current

𝐿0 Initial length

P Load

s Toughness

Sy Yield Strength

𝜎 Tensile Stress

v Voltage

𝜖 Strain

𝛿 Changes in the specimen’s gauge length

xvi

LIST OF ABBREVIATIONS

ASTM American Society of Testing and Materials

EBSD Electron Backscatter Diffraction

et al. (et alia): and others

FZ Fusion Zone

HAZ Heat Affected Zone

HRA Digital Rockwell Hardness

IIUM International Islamic University Malaysia

kN Kilo Newton

mm Millimeter

OAW Oxy-Acetylene Welding

SMAW Shielded Metal Arc Welding

UTS Ultimate Tensile Strength

UTM Universal Testing Machine

1

CHAPTER ONE

INTRODUCTION

1.1 BACKGROUND OF THE STUDY

The use of welding as joining method can be seen in almost all production of goods,

machines and equipments. Welding, the fusing of two work pieces is a precise,

reliable, cost-effective, and smart method for joining materials. Gaodi et al

mentioned that no other technique is widely used to join metals and alloys efficiently

and to add value to their products (Gaodi & Sangotra). Most of the familiar objects in

modern society, from buildings and bridges, to vehicles, computers, and medical

devices, could not be produced without the use of welding. They further elaborated

that welding goes well beyond the bounds of its simple description. In industries,

welding is widely used in fabrication, maintenance and repair of parts and structures.

While there are many methods for joining metals, welding is one of the most

convenient and rapid method available (Hussain, Lateef, Javed, & Pramesh, 2010;

Kchaou, Haddar, Hénaff, Pelosin, & Elleuch, 2014; Nathan, Balasubramanian,

Malarvizhi, & Rao, 2015).

The common applications and availability of welding make it important for us

to know and understand about the reliability of the joints produced primarily in terms

of bonding strength and hardness. The reliability of the joints produced determine

whether it is safe to be used in the applications or not. This is because most of the

welded parts will be subjected to many types of loading through their operating life

such as impact loads, weights of objects on it, fatigue loads and bending.

Since most of welding processes involve large amount of heat input during the

interdiffusion between the parent metal and filler metals, it is believed that this

2

process will affect the strength of the joint thus shortening the overall component’s

operating life. During the interdiffusion of the joint material, the microstructure of the

material might be altered and changed because of the liquefaction, cooling and

solidification phenomenon of welding. Strength of steel is influenced by its

microstructure while microstructure is controlled by the arrangement of the grain

structures in the steel. Heating and cooling of the steel influences this atomic

arrangement (Aweda, Dauda, Dagwa, & Dauda).

A welded joint is obtained when two surfaces are brought into contact with

each other and either pressure or heat or both are applied to obtain a bond. The

tendency of atoms to bond is the fundamental basis of welding. The inter-diffusion

between the materials that are joined is the underlying principle in all welding

processes. In welding the metallic materials are joined by the formation of metallic

bonds and a perfect connection is formed (Jha, 2014).

The properties of welded joints and the feasibility of welding processes are

influenced by many factors: for example, carbon migration from the low-alloy side,

microstructure gradient and residual stress situations across different regions of the

weld metal (Mvola, Kah, & Martikainen, 2014). Jha et al also stated that the goal of

welding is to obtain the best possible combination of strength and toughness for the

welded joints. Both strength and toughness are strongly influenced by the

microstructure (Jha, 2014). However, with optimal selection of welding current and

speed, it is possible to obtain a weld that provides strength comparable to the base

steel.

Shielded metal arc welding (SMAW) is one of the welding methods which

usually uses electric source to create an electric arc which melts the weld metal and

consumable electrodes to produce the weld beads that bond the weld metals. Electric

3

arc is the most popular source of heat used in welding practice. Among the several

arcs welding methods the SMAW arc welding is the oldest of the arc welding

processes. It is characterized by versatility, simplicity and flexibility. The SMAW

process is commonly used for tack welding, fabrication of miscellaneous components

and repair welding. SMAW has earned a reputation for producing high quality welds.

It is dependent on operator skill for high quality welds (Jha, 2014).

1.2 STATEMENT OF THE PROBLEM

In material technology and manufacturing, the mechanical behavior of the material is

the most important considerations in deciding the use of the material in the specific

field of applications. Constructions material usually required a high strength material

in order to sustain the high loading condition. Given an example in Ship building and

repair industries, these industries require high impact and creep resistances material as

it to be suitable in the future use conditions. A change in material’s mechanical

behavior will cause the change in their working performances primarily in their

structural performances and make them no longer suit with the required working

condition. Thus, it is very critical to investigate the effect of heat input on the strength

of welded mild steel as it plays an important role in sustaining the strength and

hardness of the materials produced.

Failure during operation should be totally avoided since it does not only

involve the damages of the broken equipment but may also lead to injuries to the user

or person near to the area. There are several researches done regarding this problem

including (Aweda et al.; Gaodi & Sangotra; Jha, 2014; Saeid, Abdollah-Zadeh,

Assadi, & Ghaini, 2008; Sathiya, Aravindan, & Haq, 2007). which try to uncover and

to study about this matter. Among these researches, none of them have discussed this

4

topic in details, so it is necessary to study on this topic to ensure higher level of

understanding.

1.3 RESEARCH OBJECTIVES

The study aimed to achieve the following objectives:

1. To characterize the mechanical behaviour of SMAW welded butt joint of

mild steel.

2. To analyse the mechanical behaviour of SMAW welded butt joint of mild

steel due to difference in current, voltage and polarity

1.4 METHODOLOGY OF RESEARCH

Since the mechanical behavior/properties of a material is very important in

determining the usage, serviceability and durability of the material, the research is

focusing on obtaining the important mechanical behaviors such as ultimate tensile

strength (UTS), hardness, toughness and the microstructure characteristics of “Mild

Steel”

The ultimate tensile strength (UTS) is the highest value of tensile stress

sustained by the material during tensile testing which usually can be seen in the stress

vs strain curve. The value of UTS indicates the ability of a material to withstand the

stress/loading applied on it before the material tends to fail or rupture occurred.

Meanwhile, the materials hardness can be said as the ability of the materials to

resist deformation to occur typically on its surface. The hardness behavior/properties

indicate the strength of the material to resist wear or scratch. It can also be defined as

the resistance to permanent indentation.

5

In many manufacturing operations and machinery components, materials are

subjected to impact or dynamic loading, for example in high speed metalworking

operations such as heading to make bolt heads, in drop forging. Hence, impact testing

of the specimen in this study can determined the toughness of the material which is

can be said as the ability or strength of the material to sustain against impact loading

or sudden load subjected on it.

The strength and hardness as well as other properties of a material are greatly

influences by its microstructure. The microstructures of the welded steels were studied

and reviewed under the optical microscope to reveal the structures of the welded

steels.

Thus, in determining the mechanical behavior or properties of the SMAW

welded butt joint of mild steel in this study; we have aimed to focus on four testings’

which are tensile test, hardness test, impact test and microstructure examination to

obtain UTS, hardness, toughness and the microstructure characteristics of the SMAW

welded butt joint of mild steel respectively as required in the objectives of the study.

6

Start

Literature Review

Preparation of Welding Materials

SMAW welding stages

Machining and Preparation of Mechanical

Testing Samples

Measurement

of Samples

Characterization of Mechanical Behaviours

-Mechanical Testing

(Tensile, Hardness, Impact & Microstructure

Examination

Data Processing and Analysis

Documentation and Reports

End

No

Yes

Figure 1.1 Flow Chart of Research Methodology

7

1.5 RESEARCH SCOPE

The scope of study is the type of welding process which is Shielded Metal Arc

Welding (SMAW). Shielded metal arc welding (SMAW) is a manual arc welding

process that uses a consumable electrode coated in flux to lay the weld. An electric

current, in the form of either alternating current or direct current from a welding

power supply, is used to form an electric arc between the electrode and the metals to

be joined. As the weld is laid, the flux coating of the electrode disintegrates, giving off

vapors that serve as a shielding gas and providing a layer of slag, both of which

protect the weld area from atmospheric contamination. Because of the versatility of

the process and the simplicity of its equipment and operation, SMAW is one of the

world's most popular welding processes. It dominates other welding processes in the

maintenance and repair industry (Gaodi & Sangotra). SMAW process can be seen in

many steel fabrications mostly for small and medium industry for example in making

housing fences, grills, furniture, and home appliances.

Mild steel is the most common steel used as it is used in nearly every type of

product created from steel, it is weldable, very hard and, although it easily rusts, very

durable. Containing a maximum of 0.14% carbon, this type of steel is able to be

magnetized and used in almost any project that requires a vast amount of metal. Its

structural strength prevents it from being used to create load-bearing girders and

structural beams (Gaodi & Sangotra). Because of its popularity and vast used of

applications, “Mild Steel” has attracted the author’s attention to focus the study on it.

The chemical composition of mild steel used in this research is shown in Table 1.1.

8

Table 1.1 The chemical composition of mild steel (Jha, 2014)

Material C Mn Si S P

Mild steel 0.14 0.76 0.28 0.013 0.010

There are several different types of weld joints that can be used in this process.

Each joint is joined in a different way and has different strengths and uses, and thus it

is important to use the right one for the right job. When two pieces of metal joined

end to end a butt weld joint is used. Butt joints are frequently used when a smooth

face is desired. Some applications that use butt joint are pressure vessels and piping.

There are several variations on butt joint including square joint; the single ‘V’ and

double ‘V’ joint (Jha, 2014).

In this research, the author has set to use butt joint in conducting the

experimental works. Since the mild steel plates used in the welding works are quite

thick (≥10mm), hence the single ‘V’ butt joint had to be used. For single ‘V’ butt

joint, the upper edge of the plate has been chamfered to 45 ̊ and prepared.

Figure 1.2 Single ‘V’ butt joint

1.6 ORGANIZATION OF THE THESIS

This thesis is organized into Five chapters. Brief descriptions of each chapter are

given below:

Documents

THE MECHANICAL BEHAVIORS OF SHIELD-ED BY MUHAMMAD …