UNIVERSITI TEKNIKAL MALAYSIA MELAKA

THE EFFECTS OF METAL INERT GAS (MIG) PROCESS

CONDITION ON HARDNESS OF STAINLESS STEEL CLADDINGS

OF A CARBON STEEL SUBSTRATE

This report submitted in accordance with requirement of the Universiti Teknikal

Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering

(Manufacturing Process)

by

AZRI SAFWAN BIN ABDUL HALIM

B050710249

FACULTY OF MANUFACTURING ENGINEERING

2011

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA

TAJUK: The Effects of Metal Inert Gas (MIG) Process Condition on Hardness of Stainless Steel Claddings of Carbon Steel Substrate

SESI PENGAJIAN: 2010/11 Semester 2 Saya AZRI SAFWAN BIN ABDUL HALIM mengaku membenarkan Laporan PSM ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:

1. Laporan PSM adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis. 2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan

untuk tujuan pengajian sahaja dengan izin penulis. 3. Perpustakaan dibenarkan membuat salinan laporan PSM ini sebagai bahan

pertukaran antara institusi pengajian tinggi.

4. **Sila tandakan (√)

SULIT

TERHAD

TIDAK TERHAD

(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia yang termaktub di dalam

AKTA RAHSIA RASMI 1972)

(Mengandungi maklumat TERHAD yang telah ditentukan

oleh organisasi/badan di mana penyelidikan dijalankan)

Alamat Tetap: No 16, JALAN AU 1C/3K

TAMAN KERAMAT PERMAI

54200 KUALA LUMPUR

Tarikh: _________________________

Disahkan oleh:

PENYELIA PSM

Tarikh: _______________________

** Jika Laporan PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh laporan PSM ini perlu dikelaskan sebagai

SULIT atau TERHAD.

APPROVAL

This report is submitted to the Faculty of Manufacturing Engineering of UTeM as

a partial fulfillment of the requirements for the degree of Bachelor of

Manufacturing Engineering (Manufacturing Process). The members of the

supervisory committee are as follow:

………………………………

Main Supervisor

(Dr. Nur Izan Syahriah Binti Hussein)

(Official Stamp)

DECLARATION

I hereby, declared this report entitled “The Effects of Metal Inert Gas (MIG) Process

Condition on Hardness of Stainless Steel Claddings of a Carbon Steel Substrate” is the

results of my own research except as cited in references.

Signature : ……………………………....

Author’s Name : Azri Safwan Bin Abdul Halim

Date : 18 May 2011

i

ABSTRACT

An experimental research titled “The effect of MIG process conditions on hardness

of stainless steel claddings of a carbon steel substrate” has been carried out. The

overall aim is to investigate how different deposition parameters affected

macrostructure, microstructure and hardness variation of stainless steel deposited

material. The cladding process will be conducted using metal inert gas (MIG) weld

method. Background knowledge about metal deposition including form of materials,

heat sources and its commercial application in relation to its cladding, process

parameter, microstructure properties, hardness variation, and macrostructure also

reviewed. This experimental method involves manipulating one variable (cladding

parameter) to determine if changes in this variable cause changes in another variable

(hardness variation). This method relies on controlled methods and the manipulation

of variables to test a hypothesis. Finally, the hardness variation of cladding stainless

steel was inspected using Rockwell test. In addition, Design Expert Software that

implemented response surface methodology technique has been used in order to

make sure the optimization of parameters while conducting this experimental

research. This research had successfully analyzed the data collected from this

experimental research. The effect of welding parameters such as current, voltage and

travel speed are directly affected hardness variations of carbon steel cladding

material. Finally, the suggestion to enhance the optimization of parameter in cladding

process also had been discussed.

ii

ABSTRAK

Sebuah penelitian eksperimental berjudul "Pengaruh keadaan proses MIG pada

kekerasan kelongsong stainless steel dari substrat baja karbon" telah dilakukan.

Objektif umumnya adalah untuk menyiasat bagaimana parameter deposisi yang

berbeza berpengaruh macrostructure, mikro dan variasi kekerasan disimpan bahan

stainless steel. Proses cladding akan dilakukan menggunakan logam inert gas (MIG)

kaedah las. Latar belakang pengetahuan tentang pengendapan logam termasuk dalam

bentuk bahan, sumber panas dan aplikasi komersil dalam hubungannya dengan

cladding nya, parameter proses, sifat mikro, variasi kekerasan, dan macrostructure

juga disemak. Kaedah eksperimen melibatkan memanipulasi satu variabel (parameter

cladding) untuk menentukan sama ada perubahan ini menyebabkan perubahan

pembolehubah dalam pembolehubah lain (variasi kekerasan). Kaedah ini bergantung

pada kaedah dikendalikan dan manipulasi pembolehubah untuk menguji hipotesis.

Akhirnya, variasi kekerasan cladding stainless steel diperiksa menggunakan uji

Rockwell. Selain itu, Ahli Design Software yang respon permukaan teknik

dilaksanakan metodologi telah digunakan dalam rangka untuk memastikan

pengoptimuman parameter ketika melakukan kajian eksperimental. Penyelidikan ini

telah berjaya menganalisis data yang dikumpul daripada kajian ini eksperimental.

Pengaruh parameter pengelasan seperti arus, voltan dan kelajuan perjalanan secara

langsung terkena kesan variasi kekerasan baja karbon cladding material. Akhirnya,

cadangan untuk meningkatkan optimasi parameter dalam proses cladding juga telah

dibincangkan.

iii

DEDICATION

For my beloved family:

Abdul Halim Bin Mohd Salleh

Siti Sabariah Binti Muhammad Syariff

For my adored friends:

Muhammad Rabani Bin Othaman

Amzar Bin Mat Yunus

Azhar Bin Abdol Aziz

Muhammad Aiman Bin Yusof

Muhd Ammar Bin Hassan

Syukri Zarizi Bin Kamaruzan

Muhammad Ikhwan Bin Muhammad

Kamarul Syaufi Bin Rasidi

BMFP’s Students

iv

ACKNOWLEDGEMENT

Alhamdulillah and thank to Allah S.W.T. with all His Gracious and His Merciful for

giving me strength and ability to accomplish this project research successfully. I

would like to take the utmost opportunity to express my sincere and gratitude to my

supervisor, Dr. Nur Izan Syahriah Binti Hussein who is always giving me supports

and guidance throughout the semester in completing this ‘Projek Sarjana Muda’.

Besides, thanks a lot to all lecturers and staffs of Faculty of Manufacturing

Engineering.

Also with the greatest thanks to my beloved parents and family who always pray and

give the encouragement while pursuing my research and project. Their sacrifices are

never being forgotten.

Finally, to all my fellow friends who involves direct or indirectly that always stand

strong beside me in giving opinions and supports throughout our relationship, I really

thankful and appreciate it.

v

TABLE OF CONTENT

Abstract i

Abstrak ii

Dedication iii

Acknowledgement iv

Table of Content v

List of Tables viii

List of Figures ix

List of Abbreviations xiv

1. INTRODUCTION 1

1.1 Introduction 1

1.2 Background of Problem 2

1.3 Problem Statement 3

1.4 Objectives 3

1.5 Overview of the Dissertations 3

1.6 Activity Planning 5

2. LITERATURE REVIEW 6

2.1 Introduction 6

2.2 Metal Inert Gas (MIG) 6

2.3 Stainless Steel 7

2.3.1 Stainless Steel composition 8

2.4 Cladding Process 10

2.4.1 Heat Source for Cladding 11

2.5 Parameter 13

2.5.1 Effect of process parameter on dilution 14

2.6 Dilution 15

2.7 Microstructure 16

2.7.1 Solidification Mode 16

2.8 Hardness 17

vi

2.9 Summary 19

3. EXPERIMENTAL METHODS 20

3.1 Introduction 20

3.2 Design of Jig 22

3.3 Research Flow 24

3.4 Material 24

3.4.1 Mild Steel 25

3.5 Direct Deposition Process 25

3.5.1 Equipment Set Up 25

3.5.2 Deposition Parameter 27

3.5.3 Cladding Process 28

3.6 Microscopical Technique 29

3.7 Rockwell Hardness Testing 30

3.8 Statistical Analysis (Response Surface Methodology) 32

3.8.1 Variable Machining Parameter 32

3.8.2 Response Variable 32

3.8.3 Design of Experiment Matrix 33

4. EFFECT OF PARAMETERS ON HARDNESS 34

4.1 Introduction 34

4.2 Design of Experiment 34

4.2.1 Design Factor 35

4.2.2 Design Summary 36

4.2.3 Relationship between Independent and Response Variable 37

4.2.4 Variables Criteria 40

4.2.5 Optimization of Variables 42

4.3 Summary 44

5. MACROSTRUCTURE, MICROSTRUCTURAL DEVELOPMENT

AND HARDNESS VARIATIONS OF CLADDINGS 45

5.1 Introduction 45

5.2 Microstructure Characterization 45

vii

5.2.1 Base metal Microstructure 46

5.3 Macrostructure of One Stainless Steel Clad 47

5.4 Microstructure Development of Stainless Steel Clad 48

5.4.1 Fusion Zone 50

5.4.2 Heat Affected Zone 51

5.5 Hardness Variation 52

5.6 Hardness Variation at Cladding Layer 53

6. DISCUSSIONS 54

6.1 Introduction 54

6.2 Effect of Current on Hardness 54

6.3 Effect of Voltage on Hardness 55

6.4 Effect of Travel Speed on Hardness 56

6.5 Optimization of Parameter Model versus Experimental 56

6.6 Establish Cladding Process 56

7. CONCLUSION AND FUTURE WORKS 57

7.1 Introduction 57

7.2 Summary of Research 57

7.3 Research Findings 58

7.4 Future Work Recommendation 58

7.5 Conclusion 59

REFERENCES 60

APPENDICES 62

A Appendix A 63

B Appendix B 68

C Appendix C 71

D Appendix D 75

E Appendix E 79

viii

LIST OF TABLES

2.1 Chemical composition of the 304L stainless steel in wt% 8

2.2 Mechanical Properties of the 304L stainless steel in wt% 9

2.3 Properties of Clad Layer 11

2.4 Process parameter varied at five levels 13

2.5 Solidification types and microstructure 17

3.1 Nominal composition of stainless steel wire (ER308L) 25

3.2 The cladding conditions for plate thickness 5mm 27

3.3 Parameter and its limit 32

3.4 Design of Experiment Matrix 33

4.1 Design factor 35

5.1 Solidification type, reactions, and resultant microstructure 48

5.2 Hardness variation at cladding layer of stainless steel 51

ix

LIST OF FIGURES

1.1 High Power Diode Laser (HPDL) System 2

2.1 Metal Inert Gas Process 6

2.2 Laser Cladding Process 10

2.3 Two stage (preplaced) and one stage (in-situ) laser cladding 11

2.4 Effect of input numeric factors in GMAW process 14

2.5 Cross section of a single clad layer with definition of the clad geometry 16

2.6 Rockwell hardness 18

3.1 The flow chart of experimental research 21

3.2 Isometric View (Jig) 22

3.3 Orthographic View (Jig) 22

3.4 Isometric View (Bar) 23

3.5 Orthographic View (Bar) 23

3.6 Filler wire used in this experimental Process 24

3.7 Gas Metal Arc Welding (GMAW) Setup for Deposition Process 26

3.8 One layer clad 28

3.9 Seven layers clad by overlapping ¼ of the clad width 28

3.10 Optical Microscope 29

3.11 Grinder machine 29

3.12 Polisher machine 30

3.13 Rockwell hardness test diagram 31

3.14 Comparison between common hardness scales 31

4.1 Design Summary 36

4.2 Relationship between current and hardness 37

4.3 Relationship between voltage and hardness 38

4.4 Relationship between travel speed and hardness 39

4.5 Variable criteria for current 40

x

4.6 Variable criteria for voltage 40

4.7 Variable criteria for travel speed 41

4.8 Variable criteria for hardness 41

4.9 Constraints and Solution for DOE 42

4.10 Relationship between optimal parameters and hardness 43

5.1 Macrostructure of low-carbon steel 0.1%-0.3% 44

5.2 Ferrite and Pearlite grain in Mild Steel Microstructure

at 20x magnification 44

5.3 130A (current), 24 inch per minute (travel speed) and 22V (arc voltage) 45

5.4 A) Current at 153A B) current at 130A 45

5.5 A) Travel speed at 32ipm B) travel speed at 27ipm 46

5.6 Cladding area and HAZ microstructure for optimal set of parameters 47

5.7 The fusion zone type FA that occurs at cladding

stainless steel (50X magnification) 48

5.8 Relationship of solidification type to the pseudobinary phase diagram 49

5.9 Ferrite along the austenitic grain boundaries in the HAZ 49

5.10 Hardness variation at different spot of cladding stainless steel 50

6.1 A) Current at 190A B) current at 115A 55

6.2 A) Result of calculation of the SDAS 55

6.3 Seven layers clad 56

xiv

LIST OF ABBREVIATIONS

CAD - Computer-Aided Design

CRES - Corrosion-Resistant Steel

DMD - Direct Metal Deposition

GMA - Gas Metal Arc

GMAW - Gas Metal Arc Welding

GTA - Gas Tungsten Arc

GTAW - Gas Tungsten Arc Welding

HAZ - Heat Affected Zone

LENS - Laser Engineered Net Shaping

MIG - Metal Inert Gas

RSM - Response Surface Methodology

SEM - Scanning Surface Microscopy

TIG - Tungsten Inert Gas

AISI - American Iron Standard Institute

AWS - American Welding Society

ASTM - American Society for Testing and Materials

DOE - Design of experiment

1

CHAPTER 1 INTRODUCTION

1.1 Introduction

Cladding is a well established process used in a variety of industries for improving

the surface and near surface properties (wear, corrosion or heat resistance) of a part,

or to resurface a component that has become worn through use. Cladding typically

involves the creation of a new surface layer having different composition than the

base material, as opposed to hardening which simply entails changing the properties

of the substrate itself in a thin surface layer. There are currently quite a number of

different techniques for performing cladding each with its own specific

characteristics in terms of the materials employed, the quality of the clad layer and

various practical issues including throughput speed, process compatibility, and cost.

Laser based processes are amongst these techniques however, their implementation

has been limited to both cost and various implementation factors.

Over the past several years, a new type of cladding tool based on high power diode

lasers has become available. In many instances, this technology offers superior

overall clad quality, reduced heat input, minimal part distortion and better clad

deposition control than traditional technology, while also delivering lower operating

cost and easier implementation than other laser based methods. Figure 1.1 shows a

schematic of the High Power Diode Laser system.

2

Figure 1.1: High Power Diode Laser System (Neill Boyle, Aidan Kennedy & John Connolly (1999)).

1.2 Background of Problem

To improve the surface properties of metallic mechanical parts, such as the resistance

against wear and corrosion, several thermal surface treatments are available for

instance are flame spraying, plasma spraying and arc welding are established

techniques. Characteristic for these techniques is the application of a surface layer

with the required properties on top of a cheap material without those properties.

Depending on the applied technique, common problems are a combination of a poor

bonding of the applied surface layer to the base material, the occurrence of porosity,

the thermal distortion of the work piece, the mixing of the surface layer with the base

material and the inability of a very local treatment.

The techniques that overcome these problems are laser cladding. Laser cladding has

been defined as “a process which is used to fuse with a laser beam another material

which has different metallurgical properties on a substrate, whereby only a very thin

layer of the substrate has to be melted in order to achieve metallurgical bonding with

minimal dilution of added material and substrate in order to maintain the original

properties of the coating material” (Komvopoulos, 1990).

3

1.3 Problem Statement

Based on this study, several main points need to be focused and questions need to be

answered at the end of the topic:

i. How different deposition parameters affected macrostructure and

microstructure of stainless steel deposited material?

ii. How different deposition parameters affected hardness of stainless steel

deposited material?

1.4 Objectives

Objectives of this study are as follows:

i. To investigate how different deposition parameters affected macrostructure

and microstructure of stainless steel deposited material.

ii. To investigate how different deposition parameters affected hardness of

stainless steel deposited material.

iii. To establish whether stainless steel can be deposited as cladding using MIG

as heat source.

1.5 Overview of the Dissertations

Chapter 1 provide fundamental of cladding process and its applications. In addition,

background of this research also reviewed in this chapter. Problem statement and

objectives of this experimental research are stated based on the task given.

Chapter 2 presents a review of the literature about the effect of (MIG) process

condition on dilution of stainless steel claddings of a carbon steel substrate. Beside,

the literature about Metal Inert Gas (MIG) heat source and process also review in this

chapter. Background knowledge about stainless steel material is also provided in

4

relation to its process parameter, dilution, and macrostructure and hardness variation.

Summary of literature review is provided at the end of this chapter.

Chapter 3 describes an experimental method of this research including design of

experiment, experimental flow, equipment set up and technique used. Introduction on

some method and approach in selecting an optimize parameters for this experimental

research also stated in this report. This chapter provides statistical analysis of direct

metal deposition. The conclusion of this chapter would interpret as research flow

along this research.

Chapter 4 describes the result of the design of experiment. Interpretation on some

result and finding of this research also stated in this chapter. This chapter provides

statistical analysis of the design of experiment. The main parameters of the process

are current, voltage and travel speed. These parameters are not independent.

Chapter 5 describes a macrostructure, microstructure development and hardness

variations of as-deposited stainless steel using wire feed method. Introduction on

some method and approach in determining macrostructure, microstructure

development and hardness variations of as-deposited also stated in this report. This

chapter provides interpretation of experiment result and its discussion.

Chapter 6 describes a conclusion of this research including interpretation of overall

research flow. The overall research objectives, scope, findings and discussions also

conclude in this chapter. Finally, this chapter provides recommendation of future

works.

5

1.6 Activity Planning

The used of Gantt chart is an effective tool for planning and scheduling operations

involving a minimum of dependencies and interrelationships in this experimental

research. On the other hand, the charts are easy to construct and understand, even

though they may contain a great amount of information. In general, the charts are

easily maintained provided the task requirements are somewhat static. Updating of a

Gantt chart will reveal difficulties encountered in the conduct of this experimental

project. Gantt chart of this experimental research is provided in Appendix A.

6

CHAPTER 2 LITERATURE REVIEW

2.1 Introduction

This chapter presents a review of the literature about the effect of (MIG) process

condition on dilution of stainless steel claddings of a carbon steel substrate. Beside,

the literature about metal inert gas (MIG) heat source and process also review in this

chapter. Background knowledge about stainless steel material is also provided in

relation to its process parameter, macrostructure properties, microstructure properties

and hardness variation. Summary of literature review is provided at the end of this

chapter.

2.2 Metal Inert Gas (MIG)

MIG welding or GMAW is a process that melts and joints metals by joint metal by

heating them with an arc established between a continuously fed filler wire electrode

and the metals as shown in figure 2.1.

Figure 2.1: Metal Inert Gas Process (O’Brien, RL (1997)).

7

Shielding of the arc and the molten weld pool is often obtained by using inert gases

such as argon or helium. This process applied a continuous and consumable wire

electrode. Carbon dioxide or argon-oxygen mixtures are suitable for arc shielding

when welding the low-carbon and low-alloy steels, while pure inert gas may be

essential when welding highly alloyed steels (Kou, 2003).

Pure inert gas shielding is essential for welding alloys of aluminum, magnesium,

copper, titanium, zirconium, stainless steels and nickel base super alloys. MIG

welding is normally perform with direct current electrode positive because it

provides a stable arc, smooth metal transfer, relatively low spatter loss and good

weld characteristics. The gas metal arc process or metal inert gas process can be used

for spot welding to replace either riveting, electrical resistance or GTA (TIG) spot

welding (Lincoln Arc Welding 2001).

Originally developed for welding aluminum and other non-ferrous materials in the

1940s, MIG was soon applied to steels because it allowed for lower welding time

compared to other welding processes. The cost of inert gas limited its use in steels

until several years later, when the use of semi-inert gases such as carbon dioxide

became common (Lincoln Arc Welding Foundation, 2001).

Advantages of using MIG welding according to Lincoln Arc Welding Foundation,

(2001) are as follows:

a) Very clean due to the application of inert shielding gas

b) Higher deposition rate, thicker work pieces can be welded at higher speed

c) Can master the welding skill in short time

2.3 Stainless Steel

In metallurgy, stainless steel, also known as inox steel or inox, is defined as a steel

alloy with a minimum of 11% chromium content by mass. Stainless steel does not

stain, corrode, or rust as easily as ordinary steel (it stains less, but it is not stain-

proof). It is also called corrosion-resistant steel or CRES when the alloy type and

8

grade are not detailed, particularly in the aviation industry. There are different grades

and surface finishes of stainless steel to suit the environment to which the material

will be subjected in its lifetime. Common uses of stainless steel are cutlery and watch

cases and bands.

Stainless steel differs from carbon steel by the amount of chromium present. Carbon

steel rusts when exposed to air and moisture. This iron oxide film (the rust) is active

and accelerates corrosion by forming more iron oxide. Stainless steels have sufficient

amounts of chromium present so that a passive film of chromium oxide forms which

prevents further surface corrosion and blocks corrosion from spreading into the

metal's internal structure.

2.3.1 Stainless steel composition

Stainless steel AISI 304 and 304L has a composition as shown below (Table 2.1)

(Balbaud, 2007).

Table 2.1: Chemical composition of the 304L stainless steel in wt% (Balbaud, 2007).

Type 304 %

Type 304L %

Carbon 0.08 max. 0.03 max.

Manganese 2.00 max. 2.00 max.

Phosphorus 0.045 max. 0.045 max. Sulfur 0.030 max. 0.030 max.

Silicon 0.75 max. 0.75 max.

Chromium 18.00-20.00 18.0-20.0

Nickel 8.00-12.00 8.0-12.0 Nitrogen 0.10 max. 0.10 max.

Iron Balance Balance

9

Table 2.2: Mechanical Properties of the 304L stainless steel in wt% (Balbaud, 2007).

UTS

Ksi (MPa)

0.2% YS

Ksi (MPa)

Elongation

% in 2”

(50.8 mm)

Hardness

Rockwell

Type 304L 85 (586) 35 (241) 55 B80

Type 304 90 (621) 42 (290) 55 B82

Stainless steel AISI 304L has a wide variety of applications in a condition where the

following properties are important:

a) Resistance to corrosion

These steels exhibit excellent resistance to a wide range of atmospheric,

chemical, textile, and petroleum and food industry exposures.

b) Resistance to oxidation

The maximum temperature can be exposed continuously without

appreciable scaling is about 1650°F (899°C). For intermittent exposure,

the maximum exposure temperature is about 1500°F (816°C).

c) Ease of fabrication

d) Excellent formability

e) Ease of cleaning

f) High strength with low weight

g) Good strength and toughness at cryogenic temperatures

h) Readily available of a wide product forms

Lee, (2006) specified that for AISI 304L stainless steel, because of the advantages

it has in mechanical and anti-corrosion properties, the area of its application has

been widely engaged in chemical, automotive and nuclear industries. In practical,

AISI 304L stainless steel weldments are often required to operate in a

dynamic mode, and consequently they are frequently subjected to impact

forces. Therefore, these components require a design that has to be fully

understood of the impact response and fractured characteristics of the 304L stainless

steel weldments.