1. Microstructure and Mechanical Properties of Similar
and Dissimilar Weld Bonded Materials
Supervised By Submitted By
MD. Nizam Uddin Nusrat Sharmin
Assistant Professor Roll: 1105075
Department of Mechanical Engineering
Khulna University of Engineering & Technology
Khulna University of Engineering & Technology

2. OUILINES
 Introduction
 Objectives
 Methodology
 Results & Discussion
 Conclusion

3. INTRODUCTION
 Welding process: Welding is a fabrication or process that joins
materials, usually metals or thermoplastics, by causing fusion process
 Material selection : Gas welding is appreciable for joining metals
when melting point difference is low. So MS-MS, Cu-Cu and MS-Cu
metals are joined by gas welding . But when melting point difference
is high, then TIG welding is used for Al-Al, Cu-Cu and Al-Cu
welding joint
 Mechanical property: For analyzing mechanical property of welding
joint, tensile and hardness test is observed. Perhaps the most
important test of a material’s mechanical response is the tensile test

4. INTRODUCTION
 Rockwell Hardness : The Rockwell hardness test determines the
hardness by measuring the depth of penetration of an indenter under a
large load compared to the penetration made by a preload
 Microstructure Analysis : The microstructure of a material can
strongly influence physical properties such as strength,
toughness, ductility, hardness, corrosion resistance, high/low
temperature behavior or wear resistance

5. OBJECTIVES
 To join mild steel- mild steel, cupper-cupper similar metal and cupper-
mild steel dissimilar metal by gas welding
 To join Al-Al, Cu-Cu similar metal and Al-Cu dissimilar metal by TIG
welding
 To observe the microstructure of similar and dissimilar weld-bonded
material
 To analysis the hardness profile and tensile strength of similar and
dissimilar weld bonded joint

6. METHODOLOGY
 Welding process
 Gas Welding : Gas welding is used to join MS-MS, Cu-Cu similar
and MS-Cu dissimilar metal
Fig 1 :Gas Welding

7. METHODOLOGY
(a) (b)
(c)
Fig 2 : (a) MS-MS joint (b) Cu-Cu joint (c) MS-Cu joint

8. METHODOLOGY
 TIG Welding : Tungsten Inert Gas equipment consists of welding
torch in which a non consumable tungsten alloy electrode is held
rigidly in the collet
 For welding Al-Al joint, alluminium alloy is mixed with tungsten
electrode and for Cu-Cu joint, cupper alloy is mixed
 For dissimilar joint, Al and Cu are welded by metal joint. In this
process, various alloy like zirconium, thorium, lanthanum etc are
alloyed with tungsten to improve arc stability, better current carrying
capacity, resistance to contamination

9. METHODOLOGY
Fig 4 : TIG Welding

10. METHODOLOGY
(a) (b)
(c)
Fig 5 : (a) Al-Al joint (b) Cu-Cu joint (c) Al-Cu joint

11. METHODOLOGY
 Mechanical Property
 Tensile Test
 Universal tensile testing machine: Tensile test of each joint is carried out
at room temperature using a Universal tensile testing machine. The basic
idea of a tensile test is to place the welding joint between two fixtures
called “grips” which clamp the material.

12. METHODOLOGY
The result of this test is a graph of stress versus strain.
Fig 6 : Tensile Test

13. METHODOLOGY
 Hardness Test
 Rockwell hardness :The Rockwell hardness test method is the most
commonly used hardness test method

14. METHODOLOGY
Fig 7 : Rockwell Hardness test

15. METHODOLOGY
 Microstructure Analysis : A optical microscope is used to reveal
details of a metallic material that are too small to be normally seen
with the unaided eye.

16. METHODOLOGY
Figure 8 : Optical Microscope

17. METHODOLOGY
Some steps to reveal the microstructure of fracture surface –
 Cutting
 Grinding
 Polishing
 Etching

18. RESULTS & DISCUSSION
 Mechanical property analysis
 Tensile strength test
We know,
Stress =
load
area
=
load
width∗thickness
Strain =
deformation
previous length

19. RESULTS & DISCUSSION
 Stress-Strain diagram
 For Gas welding : Here MS-MS, Cu-Cu similar joint and MS-Cu
dissimilar joint by gas welding are used for tensile test
 Proportional limit
 Elastic limit
 Yield point
 Ultimate point

20. RESULTS & DISCUSSION
Figure 9: Stress-Strain diagram of welding joint by gas welding
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 0.5 1 1.5 2
stresskN/〖𝑚𝑚〗^2
starin (%)
Ms-Cu
MS-MS
Cu-Cu

21. RESULTS & DISCUSSION
After yield point deformation occurs rapidly and MS-MS joint fails at
604.75 MPa. For Cu-Cu welding joint, ultimate stress is 555.9 MPa.
But when dissimilar metal joint is observed, it is seen that the joint of
MS-Cu metal breaks at lower stress than similar metal joint. The ultimate
stress of MS-Cu joint is 329.47 MPa.

22. RESULTS & DISCUSSION
 Breaking stress calculation
Joint Stress
(MPa)
Sample 1
Stress
(MPa)
Sample 2
Stress
(MPa)
Sample 3
Stress
(MPa)
Sample 4
Avg
Stress
(MPa)
Standard
Deviation
MS-MS
639 570 620 570 604.75 30.72
Cu-Cu
590 541.33 511.81 580.76 555.96 36.21
MS-Cu
354.56 294.59 393.7 275.59 329.47 54.47

23. RESULTS & DISCUSSION
Figure 10 : Breaking stress of different joint by gas welding
0
100
200
300
400
500
600
700
MS-MS Cu-Cu MS-Cu
Breakingstress(MPa)
MS-MS
Cu-Cu
MS-Cu

24. RESULTS & DISCUSSION
 For TIG Welding
Fig 11: Stress-Strain diagram of welding joint by TIG welding
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 0.2 0.4 0.6 0.8 1 1.2 1.4
stresskN/〖𝑚𝑚〗^2
strain(%)
Al-Al
Cu-CU
Al-Cu

25. RESULTS & DISCUSSION
 Breaking stress calculation
Joint Stress
(MPa)
Sample 1
Stress
(MPa)
Sample
Stress
(MPa)
Sample
Stress
(MPa)
Sample
Avg stress
(MPa)
Standard
deviation
Al-Al 295.28 275.59 314.96 255.9 285.43 25.41
Cu-Cu 246.06 226.37 285.43 196.85 238.61 37.16
Al-Cu 157.3 187.9 147.6 127.65 155.07 24.72

26. RESULTS & DISCUSSION
Figure 12 : Breaking stress of different joint by TIG welding
0
50
100
150
200
250
300
350
AL-Al Cu-Cu Al-Cu
Breakingstress(MPa)
AL-Al
Cu-Cu
Al-Cu

27. RESULTS & DISCUSSION
 Hardness test (Rockwell Hardness)
 For gas welding
Figure 16 : Rockwell hardness no for gas welding
MS-MS
Cu-Cu
MS-Cu
0
10
20
30
40
50
60
HARDNESSNO

28. RESULTS & DISCUSSION
 For TIG Welding
Figure 14 : Rockwell hardness no for TIG welding
AL-Al
Cu-Cu
Al-Cu
0
10
20
30
40
50
60
70
HARDNESSNO

29. RESULTS & DISCUSSION
 Microstructure Analysis
When stress is increased, the material is undergoing a rearrangement of
its internal molecular or microscopic structure, in which atoms are being
moved to new equilibrium positions.
When higher stress is required to reach the ultimate position where the
metal fails ,then the fracture surface is too much rough.

30. RESULTS & DISCUSSION
(a) (b)
(c)
Fig 15 : Microstructure of (a) MS-MS joint (b) Cu-Cu joint (c)MS-Cu joint

31. RESULTS & DISCUSSION
 For TIG Welding
(a) (b)
(c)
Fig 16 : Microstructure of (a) Al-Al joint (b) Cu-Cu joint (c)Al-Cu joint

32. CONCLUSION
 Similar metal joints are much familiar in mechanical engineering sector
but sometimes dissimilar metal joints are necessary for any kind of
automobiles sectors, shipyard and factories
 While observing mechanical properties, similar metals show high
breaking stress and hardness no for gas and TIG welding. It can be said
from the overall observation that while choosing metals for dissimilar
welding joint, melting point difference need to be low and metals need
to be joined by gas welding instead of TIG welding

33. THANKS
TO
ALL