I nte rnat i o nal J our na l of A pp li e d Re se a rc h 20 1 5 ; 1 (7 ): 9 7-99

ISSN Print: 2394-7500

ISSN Online: 2394-5869 Investigation of mechanical properties and microstructure
Impact Factor: 5.2
IJAR 2015; 1(7): 97-99 of GTAW on dissimilar metals
www.allresearchjournal.com
Received: 13-04-2015
Accepted: 15-05-2015 Nixon Poulose, R. Sanjeev kumar, M.P. Prabakaran, R. Rajkumar
Nixon Poulose Abstract
PG Student, Department of In this study was to join and assess the development of gas tungsten arc welding (GTAW) on dissimilar
Mechanical Engineering RVS
materials like austenitic stainless steel and low carbon steel. This GTAW weld is best suited for the thin
College of Engineering &
Technology, Dindigul-624 005
cross-section metals. This welding process can be used for continuous, spot or intermittent weld joints.
The combination of mild steel and austenitic steel are used in various industries namely valves, furnace
R. Sanjeev kumar parts, tanks, heat treatment pots and baskets, kiln cooler plates. Tests were conducted effect of different
Assistant Professor, welding process parameters on arc voltage, gas flow rate and torch distance. The mechanical properties
Department of Mechanical and microstructures and the chemical composition of the joint of the gas tungsten arc welding joints
Engineering RVS College of will be examined using universal testing machine, scanning electron microscopy (SEM), energy
Engineering and Technology, dispersive spectroscopy (EDAX).
Dindigul-624 005
Keywords: GTAW, Dissimilar Materials, UTM, SEM, EDAX.
M.P. Prabakaran
Assistant Professor, 1. Introduction
Department of Mechanical Gas tungsten arc welding (GTAW) process is an important process in many industrial
Engineering SBM College of
operations. It is possible to weld on both non-ferrous and ferrous materials with the gas
Engineering and Technology,
Dindigul-624 005 tungsten arc welding process. Depending upon the amperage used, a variety of plate
thicknesses can be welded. The process can be used for welding anything from thick material
R. Rajkumar down to very thin material and produce high quality welds. The effect of welding parameter
Associate Professor, namely arc voltage, gas flow rate and torch distance on weld strength metals namely stainless
Department of Mechanical
steel and low carbon steel.
Engineering RVS College of
Engineering and Technology, Many applications exist in industry that requires joining of carbon steel to stainless steel. A
Dindigul-624 005 typical example can be found in power generation applications. The primary boilers and heat
exchangers in coal fired power plants operate at high temperatures and environments that
permit the use of inexpensive ferritic alloy steels, while the super heater and reheater areas
operate at higher temperatures and under more severe corrosion conditions that require the
use of austenitic stainless steels. A dissimilar metal weld must be made at the alloy steel-to-
stainless steel transition region. These dissimilar metal welds are often prone premature
failure when exposed to elevated service temperature. Much work has done to understand the
mechanism of dissimilar metal weld failures in such applications [1]. When chromium content
is increased to about 11%, the resulting material is generally classified as a stainless steel.
This is because at this minimum level of chromium, a thin protective passive film forms
spontaneously on steel, which acts as a barrier to protect the steel from corrosion. On further
increase in chromium content, the passive film is strengthened and achieves the ability to
repair itself, if it gets damaged in the corrosive environment. Nickel addition in stainless steel
improves corrosion resistance in reducing environments such as sulphuric acid. It also
changes the crystal structure from BCC to FCC thereby improving its ductility, toughness
and weldability. Mo increases pitting and crevice corrosion in chloride environments.
Stainless steel is provides a combined effect of aesthetics, strength and durability. The
investigate effect of process parameters of TIG welding like weld current, gas flow rate,
Correspondence:
work piece thickness on the bead geometry of SS304. It was found that the process
M.P. Prabakaran
Assistant Professor, parameters considered affected the mechanical properties with great extent [2]. The welding
Department of Mechanical input process parameters for obtaining greater welding strength in manual metal arc welding
Engineering SBM College of of dissimilar metals. The higher the better quality characteristic was considered in the weld
Engineering and Technology, strength prediction. Taguchi method was used to analyze the effect of each welding process
Dindigul-624 005
parameters and optimal process parameters were obtained [3]. The process of Pulsed TIG
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International Journal of Applied Research

weld was exhibited lower notch tensile strength and impact 2.2 low carbon steel Chemical Composition
toughness than the parent metal due to interdendritic network The chemical composition of low carbon steel specimen is
microstructure features. Taguchi method was used to given in the table3.
optimize the pulsed TIG welding process parameters of heat-
treatable (Al-Mg-Si) aluminum alloy weldments for Table 3: Chemical composition of low carbon steel
maximizing the mechanical properties [4]. The effect of post
Elements C Si Mn P S Al Ce
weld heat treatment on the interfacial microstructure of as-
welded and PWHTed type 316L N/C-steel joint welded with Wt%(max) 0.14 0.19 0.7 0.02 0.021 0.022 0.257
Inconel 182 was investigated. These joint were PWHTed to
various temperatures between 898 to 973K for 1h results 3.2.1 Tensile Testing Observation for low carbon steel
were evaluated [5]. The micro alloying elements, such as niobium, boron,
vanadium and titanium added singly or in combination to
2. Experimental Procedure
obtain higher strength to weight ratio combined with better
2.1 Stainless Steel Chemical Composition
toughness, formability and weld ability as compared to
The chemical composition of stainless steel specimen 316L
unalloyed steel of similar strength level.
is given in the Table 1.
Table 1: Chemical composition of stainless steel 316L Table 4: Tensile test observation of low carbon steel
Elements C Si Mn P S Cr Mo Ni Test parameters Values
0.0 0.2 0.02 0.00 16.2 11.
Wt% 1.58 2.27 Ultimate tensile strength 468 Mpa
2 9 7 3 5 90
Yield Stress 352 Mpa
2.1.1 Tensile Testing Observation for Stainless Steel % Elongation 28 %
Specimen
Table 2: Tensile test observation of SS specimen 2.3 Filler Metal
Test parameters Values The filler metal used in this project is a stainless steel 316L
Ultimate tensile strength 513.18Mpa grade filler rod of Ø2.5mm x 1000mm. This filler rod having
Yield strength 255.90Mpa 490 Mpa ultimate tensile strength 40% elongation. The
% Elongation in 50mm GL 55.50% chemical composition of filler rod is given below

Table 5: Chemical Composition of Filler Rod

Elements C Si Mn P Cu S Cr Mo Ni
Wt% (max) 0.3 0.30-0.65 2.0-3.0 0.03 0.75 0.03 18.0-20.0 23.15 11.0-14.0

2.4 Process parameters ferrite phases appear in the microstructure analysis. It was
The factors which have a significant influence on weld found that the pearlite percentage was always higher than the
strength of tungsten inert gas welding were identified. They ferrite in both weld and heat affected zones. The hardness
are weld shielding gas flow rate, arc voltage, torch distance value is lower than the weld zone because the percentage of
of GTAW. ferrite is higher in the heat affected zone. The higher amount
of ferrite influences the softening of the heat affected zone
Table 6: Parameters [6]. The energy disperse X-ray (EDX) finding was conducted

to differentiate the chemical composition of the fusion zone.

Factors Gas flow rate Torch distance Voltage
Notation G T V
Figures 2 and 3 are showing the EDX test results for
Unit lpm mm volts dissimilar material GTAW joint. The results are showing that
Level 12.5 1.5 170 the chromium to nickel ratio was increased so more ferrite
phases were induced at the welded zone. It can be said in
3. Result and Discussion another way the vermicular and lathy ferrite increase during
welding process [6]. It has been noticed from the energy
disperse X-ray test EDX that the carbon content is
significantly increased at the fusion zones although the
carbon content at fusion zone is (17.07).

Fig 1: SEM micrograph of fusion zone.

Micro structural analysis is made on a small volume weld

zone and heat affected zone of the test specimen. Pearlite and
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International Journal of Applied Research

 The chromium to nickel ratio was increased so more

ferrite phases were induced at the fusion zone, it gives
high corrosion resistance

5. Reference
1. Ferren JD, Dupont JN, Nokecker FF. “Fabrication of a
carbon steel-to-stainless steel transition joint using direct
laser deposition”, Supplement to the Welding Journal,
March, 2007.
2. Experimental investigation of weld characteristics for a
single passes TIG welding with SS304. (Gadewar S.P.,
Peravli Swaminadhan, Harkare M.G., Gawande S.H,-),
2010.
3. Lenin N, Sivakumar M, Vigneshkumar D. “Process
parameter optimization in ARC welding of dissimilar
metals”, Thammasat international Journal of Material
science Technology, 2010, 15(3).
4. Kumar A, Sundarrajan S. “Effect of welding parameters
on mechanical properties and optimization of pulsed
Fig 2: EDX mapping analysis of fusion zone. TIG welding of Al-Mg-Si alloy”. Int J Adv Manuf
Technol 2009; 42:118-125.
5. Jithendar Reddy K, Manzoor Hussain M, Sujith Sathyan,
Gopala Krishna G. Analysis of Interfacial
Microstructure of Post Weld Heat Treated Dissimilar
Metal Weld of Type 316LN/C-Steel Joint. Journal of
Mechanical and Civil Engineering, e-ISSN: 2278-1684,
p-ISSN: 2320-334X 2013; 8(2):01-06.
6. Lenin N, Sivakumar M, vigneshkumar D. “Process
parameter optimization in arc welding of dissimilar
metals”, Thammasat Int. J. Sc. Tech., july- September,
2010; 15(3).
7. Shamsul JB, Hisyam MM. Study of spot welding of
austenitic stainless steel type 304. Journal of applied
sciences research 2007; 3(11):1494-1499.
8. Ranfeng Q, Shinobu S, Chihoro I. “Effect of interfacial
reaction layer continuity on the tensile strength of spot
Fig 3: EDX Chemical composition on fusion zone
welded joints between aluminum alloy and steels”,
Materials and design 2009; 30:3686-3689.
The heating process dissipates some of the chemical 9. BW Cha, SJ Na. “A study on the relationship between
compositions during welding and therefore carbon content welding conditions and residual stress of resisistance”,
was increased in percentage [7]. Besides the chromium journal of Manufacturing systems 2003; 22(31):356-363.
content from stainless steel side (18%) is also reduced to
10. Patil US, Kadam MS. Effect of the welding process
13.53% and the nickel content is from 14% to 4.36%.
parameter in MMAW for joining of dissimilar metals
however the primary content (iron-Fe) occupies the zones
and parameter optimization using artificial neural fuzzy
with major percentage [8]
interface system. International Journal of Mechanical
Engineering and Technology 2013; 4(2):79-85.
4. Conclusion
This study was to join and assess the development of gas
tungsten arc welding (GTAW) on dissimilar materials like
austenitic stainless steel and low carbon steel. Tests were
conducted effect of welding process parameters on arc
voltage, gas flow rate and torch distance.
 The mechanical properties and microstructures and the
chemical composition of the joint of the gas tungsten arc
welding joints will be examined using universal testing
machine, scanning electron microscopy (SEM), energy
dispersive spectroscopy (EDAX).
 The tensile strength and elongation of the weld are
approximately identical with those of Base metal and the
fracture of tensile specimen occurs at the base metal
from the heat affected zone.
 The fully penetrated weld are obtained at the GTAW
voltage of (170 volts) and the gas flow rate (12.5 lpm)
and the torch distance (1.5 mm) respectively.

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