DETERMINATION OF DEFECT AND MECHANICAL PROPERTIES FOR
TUNGSTEN INERT GAS (TIG) WELDED CARBON STEEL
MOHD FITRI BIN MUSTAPHA
B041210323
BMCS
Email: fitri5911@gmail.com
Draft Final Report
Projek Sarjana Muda II
Supervisor: PUAN ANITA AKMAR BINTI KAMAROLZAMAN
Faculty of Mechanical Engineering
Universiti Teknikal Malaysia Melaka
MEI 2015
DECLARATION
I declare that this report entitled “Determination of Defect and Mechanical
Properties for Tungsten Inert Gas (TIG) Welded Carbon Steel Plate” is the result of
my own research except summaries and quotations which have been acknowledged.
The report has not been accepted for any other degree and is not concurrently
submitted in candidature of any other degree.
Signature: ................................................................
Name:
MOHD FITRI BIN MUSTAPHA
Date:
..............................................................
ii
Dedicated to my parents,
Mustapha b. Md. Daud & Kamariah bt Md.Din
My respectful lecturer,
and
My entire friends in UTeM
For their encouragement
iii
ACKNOWLEDGEMENT
First of all, I would like to take this opportunity to express my gratefulness to
Allah s.w.t for blessing me with strength to complete this project. I would like to
thanks and acknowledge my supervisors, Pn. Anita Akmar bt. Kamarolzaman for the
guidance and assistance throughout this project.
I also would like to thanks Final Year Undergraduate Project Coordinator,
Engr. Dr. Azma for the effort his put in providing useful additional information and
also guidance. Not forgotten, to all my lectures of Structure and Material Department
from Faculty of Mechanical Engineering whom shared knowledge and valuable
information to complete this research.
Most important of all, thanks to my whole family and fellow friends whom
involved directly or indirectly for their ever loving care towards the success of this
study.
iv
ABSTRACT
This is a research on studying the effect of current and voltage towards
weldment and mechanical properties in welding of carbon steel of plate using
Tungsten inert gas welding (TIG). Construction growth rapidly year by year.
Welding technique for plate is the one of factor to ensure the quality of joint. In
fabrication process, welded joint will be tests to ensure the quality and defect free.
The familiar problem happen at plate joint is corrosion, misalignment, erosion,
cracking and etc. lead to leakages or explosion Welded joints may be tested either
destructively or non-destructively following the acceptance criteria and standards
The focus of this project is to detect defect that occur inside the welded butt joint on
a carbon steel plate using Non-Destructive Testing Method (NDT) which are Visual
Inspection (VI), Magnetic Particle Inspection (MT), dye-penetrant testing (PT) and
Ultrasonic Testing (UT). This project also investigate Mechanical properties consists
of hardness and bending. The data of the properties can be obtained from several
testing procedure which are specifically designed for it. The test that going to be
conducted are bending test and hardness test. In this project specimen are develop
from carbon steel plate. These specimen will be joint together on butt joint using TIG
welding technique. NDT inspection will be carried out to detect all the defect. The
result outcome is to come out with the appropriate welding procedure for butt joint
plate using TIG welding technique for produce the enhanced quality of weldment.
v
ABSTRAK
Ini adalah kajian mengenai mengkaji kesan arus dan voltan ke arah hasil
kimpal dan sifat mekanikal dalam kimpalan keluli karbon plat menggunakan
Tungsten kimpalan gas lengai (TIG). Pertumbuhan pesat pembinaan tahun ke tahun.
Kimpalan teknik untuk plat adalah salah satu faktor untuk memastikan kualiti
terjamin. Dalam proses fabrikasi, sendi dikimpal akan menjadi ujian untuk
memastikan kualiti dan bebas kecacatan. Masalah biasa berlaku pada plat bersama
adalah kakisan, salah jajaran, hakisan, keretakan dan lain-lain menyebabkan
kebocoran atau letupan dikimpal sendi boleh diuji sama ada ujian musnah atau ujina
tanpan musnah mengikuti kriteria penerimaan dan standard. Fokus projek ini adalah
untuk mengesan kecacatan yang berlaku di dalam sendi punggung yang dikimpal
pada plat keluli karbon dengan menggunakan Kaedah Ujian Tanpa Musnah (NDT)
yang Pemeriksaan Visual (VI), Pemeriksaan Zarah Magnetik (MT), ujian pewarna
penusuk (PT) dan Ujian Ultrasonik (UT). Projek ini juga menyiasat sifat-sifat
mekanikal terdiri daripada kekerasan dan lentur. Data sifat-sifat mekanikal ini boleh
didapati dari beberapa prosedur ujian yang direka khusus untuk itu. Ujian yang akan
dijalankan adalah ujian lenturan dan kekerasan ujian. Dalam projek ini adalah
membangunkan spesimen daripada plat keluli karbon. Ini spesimen akan bersama
bersama-sama pada sendi punggung menggunakan teknik kimpalan TIG.
Pemeriksaan NDT akan dijalankan untuk mengesan semua kecacatan itu. Hasil
dijangka akan datang dengan prosedur kimpalan yang sesuai untuk plat bersama
menggunakan teknik kimpalan TIG untuk menghasilkan kualiti yang dipertingkatkan
hasil kimpal.
vi
TABLE OF CONTENT
CHAPTER
TITLE
PAGE
SUPERVISOR DECLARATION
AUTHOR DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENT
LIST OF TABLE
LIST OF FIGURE
CHAPTER 1
CHAPTER 2
INTRODUCTION
1
1.1
Background
3
1.2
Problem Statement
4
1.3
Objectives
5
1.4
Scope
5
LITERATURE REVIEW
6
2.1
Welding
6
2.1.1
Tungsten Inert Gas welding (TIG)
7
2.1.2
The weld joint, material, quality
8
and testing
2.2
2.1.3
Heat-affected zone (HAZ)
10
2.1.4
Welding defect
10
2.1.5
Steel
11
2.1.6
Testing method of welds
12
Mechanical Testing
vii
12
2.2.1 Bend test
13
2.2.2 Hardness test
14
2.2.2.1 Rockwell hardness testing
2.3
Non-destructive test method
15
2.3.1
Visual inspection
16
2.3.2
Liquid penetrant testing
17
2.3.2.1 Penetrant
18
2.3.2.2 Developer
19
Magnetic particle inspection (MT)
20
2.3.3.1 Magnetic particle
22
Ultrasonic testing
23
2.3.3
2.3.4
2.3.4.1 Advantages and disadvantages (UT)
CHAPTER 3
14
25
METHODOLOGY
28
3.1
Introduction
28
3.2
Flow Chart
29
3.3
Gantt Chart
30
3.4
Preparation of plate specimen
31
3.4.1 Bevelling specimen
31
3.5
welding sample
32
3.6
Non-destructive test (NDT) inspection
33
3.6.1
Visual inspection
33
3.6.2
Fluorescent and Dye penetrant
33
3.6.2.1 Procedure liquid penetrant testing
34
Magnetic particle inspection (MT)
35
3.6.3.1 Equipment
35
3.6.3.2 Procedure MT
36
Ultrasonic Testing Inspection (UT)
37
3.6.4.1 Equipment
38
3.6.4.2 Standard Procedure (UT)
39
3.6.3
3.6.4
viii
CHAPTER 4
3.7
Rockwell Hardness Test
39
3.8
Bend test
40
RESULT AND DISCUSSION
41
4.1
Introduction
41
4.2
Non-Destructive Test Result
41
4.2.1 Visual Inspection Result and Analysis
41
4.2.2 Visual Inspection Result
42
4.2.3 Magnetic Particle Inspection Result (MPI)
44
4.2.4 Magnetic Particle Inspection
46
Result (MPI) Analysis
4.2.5 Penetrant Testing Result
46
4.2.6 Ultrasonic Testing Result
48
4.2.6.1
Ultrasonic Testing Result
49
4.2.6.2
Type of Defect Analysis
52
Using Ultrasonic
Testing Inspection
4.3
Rockwell Hardness Test Result
53
4.4
Bend Testing result
55
4.4.1 Bend Test Analysis
57
Discussion
57
4.5
CHAPTER 5
CONCLUSION AND RECOMMENDATION
64
5.1
CONCLUSION
64
5.2
RECOMMENDATION
66
REFERENCE
APPENDIX
ix
LIST OF TABLES
NO
TITLE
PAGES
1
Table 2.1: Electrode table
8
2
Table 3.1 Probes angle table
38
3
Table 4.1: Ultrasonic testing data location of defect sample 1
49
4
Table 4.2: Ultrasonic testing data location of defect sample 3
51
x
LIST OF FIGURES
NO. FIGURE
TITLE
PAGE
2.1
Welding category chart
6
2.2
Weldment zone
9
2.3
Welding defect
11
2.4
Carbon steel plate
12
2.5
Atom structure of carbon steel
12
2.6
Bend test machine
13
2.7
Bend position
13
2.8
Rockwell hardness testing
15
2.9
Aided equipment
16
2.10
Eyes angle
17
2.11
Stage of dye penetrant
19
2.12
Dye penetrant aerosol can
19
2.13
Flux leakages
21
2.14
Magnetic field
21
2.15
Magnetic particle testing
22
2.16
UT transducer
24
3.1
Flow chart
29
xi
3.2
Gantt chart
30
3.5
Permanent York
30
3.3
Carbon steel plate
31
3.4
Bend saw machine
31
3.5
Bevel angle
32
3.6
Bevelling plate
32
3.7
1G positon TIG welding
32
3.8
TIG weldment
32
3.9
Dye-penetrant spray can
34
3.10
AC yoke
35
3.11
Black Visible Magnetic Particle Wet Method Prepared
36
Bath
3.12
Magnetic particle testing
37
3.13
Rockwell hardness test
39
3.14
Rockwell hardness test machine
40
3.15
Instron Bend Test Machine
40
4.1
Visual inspection for specimen 1
42
4.2
Visual inspection for specimen 2
43
4.3
Visual inspection for specimen 3
43
4.4
Magnetic particle inspection of sample 1
44
4.5
Magnetic particle inspection of sample 2
45
4.6
Magnetic particle inspection of sample 3
45
4.7
Penetrant testing on welded specimen 1
46
4.8
Penetrant testing on welded specimen 2
47
xii
4.9
Penetrant testing on welded specimen 3
47
4.10
Angle beam probe in Ultrasonic testing for the welding
inspection
48
4.11
Plotting card and tracing paper Ultrasonic Testing
49
inspection For specimen 1
4.12
Schematic diagram location of defect in sample 1
50
4.13
Defect lack of sidewall fusion signal at specimen 1
50
4.14
Schematic diagram location of defect in sample 3
51
4.15
Defect (a3) Porosity signal at specimen 3
52
4.16
Defect (b3) Tungsten Inclusion signal at specimen 3
52
4.17
Weldment hardness area test result
53
4.18
Parent metal hardness area test result
53
4.19
HAZ area test result
54
4.20
The schematic diagram point location for the Rockwell
54
hardness test measurement
4.21
Bending test for specimen 1
55
4.22
Bending test for specimen 2
55
4.23
Bending test for specimen 3
56
4.24
Maximum load for specimen
56
4.25
Maximum flexural load for specimen
56
4.26
Crack at specimen
58
4.27
No crack occur at specimen 2
58
xiii
4.28
Undercut occur at specimen 3
59
4.29
cracking at specimen 3
59
xiv
1
CHAPTER 1
INTRODUCTION
1.0 INTRODUCTION
Nowadays, steel is one of the important things in the industry. In industrial
such as automotive, oil and gas, and aerospace using steel as structure and
components for their parts. This industry needs a high quality parts to sustain the
parts lifetime and also to avoid hazard. One of the main factor to evaluate the steel
component parts is from the joint. One of famous jointing technique is by welding.
Welding is one of the most important means of fabrication available to industry.
Actually, many products could not even be made without the use of welding for
example guided missile, nuclear plants, jet aircraft, transportation vehicle and
literally thousands of others (Arcelor Mittal, 2012). Many problems that inherent to
welding can be avoided by proper consideration of the particular characteristics and
requirement of the process. There are many type of welding technique used at
automotive and aerospace industry such as Shielded Metal Arc Welding (SMAW),
Metal Inert Gas (MIG), and Tungsten Inert Gas (TIG). Many development and
construction has been done for this industry. Keeping a good quality for aerospace
and automotive parts throughout the years is not that simple. If have any failure,
pollution and accident will be happen. For this reason, the parts must have a good
quality and robust.
Generally the quality of a parts depending on the many factor such as welding
technique, geometric shape, design and nature of the applied stress. Welding is most
important process in components fabrication (Arcelor Mittal, 2012). Welding is
process join together (metal parts) by heating the surfaces to the point of melting
2
with a blowpipe, electric arc, or other means, and uniting them by pressing,
hammering, etc. pipe will be connected using welding technique. Welding have
various technique such as shielded metal arc welding (SMAW), gas metal arc
welding (GMAW), Tungsten Inert Gas (TIG), and many more. TIG welding
technique can produce the best quality of weld such as good weld bead appearance
and good weld bond. By the way, every technique have their own advantages and
benefit.
In fabrication process, welded joint will be tests to ensure the quality and
defect free. Welded joints may be tested either destructively or non-destructively
following the acceptance criteria and standards. The acceptance criteria and
standards are available from many organization such as the American Society for
Testing and Material (ASTM), the American Society of Mechanical Engineering
(ASME), American Petroleum Institute (API) and many more. Testing technique can
be categorized into destructive test (DT) and non-destructive test (NDT). Destructive
test (DT) includes methods where your material is broken down in order to determine
mechanical properties, such as strength, toughness, tensile and hardness. Nondestructive test is also used as part of in-service inspections or preventive
maintenance to quantify the status of critical components and equipment without
causing any damage. NDT have various technique such as Visual inspection (VI),
Magnetic particle Inspection (MPI), Radiography Testing (RT), Dye-Penetrant
Testing (PT), and Ultrasonic Testing (UT), Eddy Current Testing (ET). Every NDT
technique have their own advantages, specialty and limitation. Benefits of using
NDT is can prevents failure or break down of critical equipment. It also save money
and time.
The familiar problem happen at aerospace and automotive parts is corrosion,
misalignment, erosion, cracking and etc. lead to crack or explosion. The problem can
cause pollution and accident. For the safety reason. To control this factor, preventive
and monitoring action is compulsory. To ensure the safety of the parts, NDT can be
used to apply the monitoring and to detect the early sign before the accident happen.
3
1.1 BACKGROUND
In this research, the specimen will be using is low carbon steel plate.
Chemical composition for this specimen according ASTM A106 contained carbon
max 0.25%, manganese 0.27% to 0.93%, phosphorus max 0.035%, sulfur max
0.035%, silicon min 0.1%, chromium max 0.40%, and nickel max 0.40%. The tensile
requirements for this specimen also according ASTM A106 is 48000 psi for tensile
strength and 30000 psi for yield strength. Welding method used for this study is
Tungsten Inert Gas (TIG). This method most high quality welding method in
industry because it can produce high quality joint, low-distortion welds, give precise
control of weld heats. The Tungsten Inert Gas (TIG) process is applicable when the
highest weld quality is required. It can be used to weld almost all types of metals.
The operator has excellent control of heat input, and vision is not limited by fumes or
smoke from the process. The power source for this machine provides constant
current and may be either direct current (DC) or alternating current (AC) and
measured in voltage and current. TIG uses a non-consumable electrode and a
separate filler metal with an inert shielding gas. (D. Yapp,2004) TIG process welding
set utilizes suitable power sources, a cylinder of argon gas, welding torch having
connection of cable for current supply, tubing for shielding gas supply and tubing
water for cooling torch (D. Yapp,2004). Welding joint is also important part in
fabrication, the welding joint used for this project is butt joint. Butt joint are chosen
because the durability, simplicity and uniformity factor. Each weldment have
possibility defect will occur. Taking into consideration environmental factors of
pipeline, possible defect will occur such as porosity, misalignment, lack of fusion,
cold cracking, and lack of penetration and others. Defect can lead to decreased
quality of weldment, thus resulting in a weak joint strength.
The most efficient detecting the defect and strength on the pipe is
combination of suitable non-destructive testing (NDT) method and mechanical
testing. For this study, the suitable NDT method is Visual Inspection (VI), Magnetic
Particle Testing (MT), Ultrasonic Testing (UT) and Dye-Penetrant Testing (PT).
4
Each NDT methods have their own capability and limitation. Normally VI is the first
step in the examination process. VI is the process of evaluating of system and
component by using human sensory and aided only by mechanical enhancement such
as magnifiers, dental picks and etc. For VI methods can detect only on surface defect
but this method save time and cost. It’s different for MT method, this method can
detect surface and sub-surface defect in ferromagnetic material. Ferromagnetic
material are material that can be magnetized. MT uses magnetic fields and small
magnetic particles to detect flaws in components. Dye-penetrant testing (PT) is
method can detect the surface flaws. The basic principle of this method is ability of a
liquid to be drawn into a surface breaking flaw by capillary action. After a period of
time called ‘dwell’, excess surface penetrant is removed and developer applied. The
developer will absorb back the dye from the flaw to reveal its presence. Lastly for
NDT method is ultrasonic testing (UT). UT uses high frequency sound energy to
conduct testing. The equipment of the UT will produce high frequency ultrasonic
energy and will propagates through the material in the form of wave. If any
discontinuity in the wave path, the wave will be reflected back to the receiver and
from the signal information about the flaw will displayed on a screen.
Mechanical testing will be used for investigate material mechanical properties
such as strength, hardness, toughness, durability and etc. Normally the testing will be
conduct at laboratory. The test performed for this research is bending test, impact test
and hardness test.
1.2 PROBLEM STATEMENT
Nowadays, many application of welding made of carbon steel such as bridge
structure, automotive parts, aerospace parts, pipelines and many more. All stated
above
need to be robust and of good quality. Weldment on these joint of parts or
pipes are likely to failure during its life time
Various types of defect on welds are typically unique to the specific welding
procedure. Some of the defects that were left undetected can fail lead to failure
during in-service application due to fatigue, stress corrosion cracking or other
mechanisms that way lead to failure.( Prof. DR. Muna Khethier Abba), n.d]
Generally the quality welded of pipeline is depending on many factor such as
welding parameters, welding current, welding speed and gases. In order to produce
5
high quality pipeline,(B.S Paveen Kumar,2012)all the factor have to be put into
consideration and inspection after the welding must be thoroughly made to avoid
sudden unexpected failure to the weld structure.
This project in going to develop standard of procedure for the examination of
defect in pipe based on investigate using nondestructive test method dye-penetrant
testing (PT), magnetic particle testing (MT), visual inspection (VI), and ultrasonic
testing (UT). This project also investigate mechanical properties of material and joint
using mechanical testing bending test, and hardness test.
1.3 OBJECTIVE
1. To perform the butt joint welding on pipe using TIG with different current and
voltage
2. To inspect the defect on V butt joint pipe using NDT method (VI, PT, MPI, and
UT) and prepare the standard of procedure.
3. To study mechanical properties using bend test, and hardness test
1.4 SCOPE
1. Produce the plate specimen by using tungsten inert gas (TIG)
2. Perform butt joint welding technique on carbon steel plate with different parameter
which is voltage and current.
3. Using Nondestructive test (NDT) inspection which is visual inspection, ultrasonic
inspection, magnetic particle inspection, and liquid penetrant testing.
4. Investigate and analyze the mechanical testing on the sample using bend test and
hardness test.
6
CHAPTER 2
LITERATURE REVIEW
2.1 WELDING
WELDING
BRAZING
AND
SOLDERING
FUSION
CHEMICAL
Oxy-acetylene
ELECTRICAL




ARC
RESISTANCE
ELECTRON
LASER BEAM
SOLID
STATE
CHEMICAL
ELECTRICAL




RESISTANCE
Figure 2.1: welding category chart


MECHANICAL
DEFUSION
EXPLOSION
COLD
FRICTION
ULTRASON
IC
7
Welding is a joining process that produces a joining process that produces a
coalescence of metals (or non-coalescence of metals (or non-metals) by heating them to
the metals) by heating them to the welding temperature, with or without the application
of pressure, or by pressure alone, and with or without the use of filler metals.
It’s classified to three category namely fusion, brazing and soldering and solid
state. Fusion welding can be defines as the melting together and coalescing of materials
by means of heat, usually supplied by chemicals or electrical means; filler metals may or
may not be used. Soldering and Brazing do not involve melting the work piece but rather
a lower-melting-point material is melted between the work pieces to bond them together.
2.1.1 Tungsten Inert Gas (TIG)
In this project, the focus on this type of welding. TIG is the highest quality, low
defect absence and low heat effected zone. In this process, heat will generated by an
electric arc between base metal and non-consumable tungsten electrode. When the
electrode touching the base metal, electrode movement is manually controlled TIG
welding can use both AC (alternating current) and DC (direct current), the constant
current DC power source is usually used with all types of electrode (thoriated and
zirconiated) irrespective of base metal (ferrous and non-ferrous) and DC produces
smoother welding output than AC. (Peter W Muncaster, 1991).“The maximum current a
given diameter of electrode can carry is determined by the onset of overheating and
melting.
The arc welding area covered with inert gas to reducing the shielding gas, to
protect the weld pool and consumable tungsten electrode. The welding process also can
be operated without filler to joining plates. There are many types inert gas used for TIG
welding technique such as argon, helium, krypton, xenon, radon and neon. Normally
argon gas used for this welding technique. The main purpose of inert gas is to protect
and prevent from any contamination of welding area or weld pool (W. Lucas ,1990)
8
TIG welding equipment
TIG process welding set utilizes suitable power sources, a cylinder of argon gas, welding
torch having connections of cable for current supply, tubing for shielding gas supply and
tubing water for cooling the torch. The shape of the torch is characteristic, having a cap
at the back end to protect the rather long tungsten electrode against accidental breakage.
Application
The TIG welding technique is suitable for welding joints for wide range 8mm to
10mm thickness. The common used in industry for TIG welding technique is for sheet
material and butt joint on piping. Beside the application, TIG also suitable for alloy,
stainless steel fabrication and many more (W. Lucas, 1990)
2.1.2 The Weld joint, Material, Quality and Testing
In welding, as the heat source interacts with the material, the severity of thermal
excursions experienced by the material varies from region to region, resulting in three
distinct regions in the weldment. The important parts of the weldment can be identified
at three zones base metal, heat-affected zone (HAZ) and weld metal.
9
Figure2.2: Weldment zone
(http://www.tms.org/pubs/journals)
The zone at the center of the weldment called fusion zone, the microstructure in
the fusion zone depend on solidification of weld pool. The fusion zone is composed of a
mixture of the base and the filler metal. Base metal zone is zone without mixture of filler
metal.
2.1.3 Heat-affected Zone (HAZ)
Heat-affected zone are define as the area of base metal which is has had its
microstructure and properties altered by welding. The heat from the welding process and
subsequent re-cooling causes this change in the area surrounding the weld (Dr. Paul
Scott, n.d).
The properties and microstructure of the HAZ depend on the rate heat input and cooling
rate. It also depending on temperature to which this zone was raised. In addition to
metallurgical factors (such as the original grain size, grain orientation, and degree of
prior cold work), physical properties influence the size and characteristic of the HAZ.
The weld HAZ contains potentially crack susceptible metallurgical structure, hardness
variation and residual stresses.
10
2.1.4 Welding defect
Defect or discontinuity is a flow or flaws that by nature or accumulated effect
render a part or product unable to meet minimum applicable, acceptance standards or
specification. Welding defect can affect the quality of the weld. Defect can be reduce by
using a right technique and do the proper weld preparation such as use proper welding
amperages and voltages, clean the joint fusion faces, pre-heat weld or re-dry the base
metal and electrode. Early detection is important to ensure the quality of the welding and
to avoid the crack become worse.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
Crater crack
Face crack
HAZ crack
Lamellar tear
Longitudinal crack
Root crack
Root surface crack
Throat crack
Toe crack
Transverse crack
Under bead crack
Weld interface crack
Weld metal crack
lamination
Figure2.3: welding defect
(http://wiki.iploca.com/download/attachments)
2.1.5 Steel
Steel is a material that generally strong, durable, malleable containing alloying
element such as manganese, chromium, nickel and carbon. When carbon is the primary
alloying element, its content in the steel is between 0.45 to 0.75 percent carbon, these