International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 2, Issue 6, June 2013
ISSN 2319 - 4847
Impact behaviour and Micro structural analysis
of AISI 316L stainless steel weldments
N.V. Amudarasan1, K. Palanikumar2 and K. Shanmugam3
1
Research Scholar, Department of Mechanical and Production Engineering, Sathyabama University, Chennai, India.
2
Department of Mechanical engineering, Sri Sairam Institute of Technology, Chennai, India
3
Department of Manufacturing Engineering, Annamalai University, Chidambaram, Tamil Nadu, India.
ABSTRACT
The effect of filler metals such as austenitic stainless steel (308L) and duplex stainless steel (2209) on impact behaviour of the
gas tungsten arc welded austenitic stainless steel (316L) was investigated. Rolled plates of 3mm thickness were used as the base
material for preparing single ‘V’ butt welded joints. Pendulum type impact machine was used to evaluate the impact behaviour
of the welded joints. From this investigation, it was found that the joints fabricated by austenitic stainless steel filler metal
showed superior toughness compared to the joints fabricated by duplex stainless steel filler metal. The welded fracture
morphology was studied using scanning electron microscope.
Keywords: Austenitic stainless steel, Duplex stainless steel, SEM
1. INTRODUCTION
Austenitic stainless steel (ASS) such as type 316L is usually preferred over other austenitic varieties as a structural
material due to its higher corrosion resistance and superior mechanical properties both at low and high temperatures.
Micro structural changes due to welding have been reported by several researchers [1-4]. Rafal et al. [5] investigated
measurement of mechanical properties in a 316L stainless steel welded joint and found that the highest mechanical
properties are revealed in the material taken from the heat affected zone than the weld material. . Mataya et al. [6] and
Harvey II et al. [7] have studied the impact behaviour of 304L stainless steel by high-energy-rate forging and Charpy’s
test, respectively. Ibrahim et al.[8] made a comparative evaluation of impact behaviour of different stainless steel
weldments at low temperatures and found that remarkable decrease was observed for the duplex stainless steel
compared with 304L and 316L.
Duplex stainless steels are found increased application in the chemical, oil and gas industries, petrochemical process
plants, pulp and paper industry, pollution control equipment, transportation and for general engineering to their
outstanding corrosion resistance and mechanical properties [9]. The high corrosion resistance and the excellent
mechanical properties combination of duplex stainless steels can be explained by their chemical composition and
balanced duplex microstructure of approximately equivalent volume fractions of ferrite and austenitic [10].
Most of the reported literature focused on different types of welding methods, crack properties, weld geometry, etc,
Hence, the present investigation is carried out to study the effect of austenitic stainless steel and duplex stainless steel
filler metal on impact properties and the fracture impact surfaces were analyzed by scanning electron microscope
(SEM).
2. EXPERIMENTAL PROCEDURE
AISI 316L austenitic stainless steel in the form of plate of size 55l x 10b x 3t mm were annealed. The composition of the
materials used was evaluated by spectrographic analysis and is given in Table 1.
Weld joint preparation was done by machining on both edges to make single V butt joint. GTA welding was made in
flat position using ESAB India Limited making machine. All the welding processes were completed in single pass.
Filler metal used for GTA welding such as austenitic stainless steel (ASS) and duplex stainless steel (DSS) was in the
form of wire having diameter 2.0mm. The welding conditions are detailed in Table 2.
Volume 2, Issue 6, June 2013
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 2, Issue 6, June 2013
ISSN 2319 - 4847
The welded joints were sliced using power hacksaw after which it was machined to the required dimensions for
preparing impact test specimens and photographs as authenticated in Figure 1 and 2. Necessary guidelines were
followed for preparing and testing the impact specimens. Impact test was conducted at room temperature using
pendulum type impact testing machine with a maximum capacity of 300J, ASTM E23-04, Specifications were followed
for preparing and testing the specimens. Since the plate thickness is small, sub sized tensile and impact specimens were
prepared.
Table 1 : Chemical composition of Base metal and Filler metals
Material
C
Mn
P
S
Si
Cr
Ni
Ti
Mo
Cu
Fe
Base metal
(316L)
0.022
1.410
0.029
0.003
0.374
16.69
9.80
0.004
2.04
0.49
Bal.
Filler metal
(308L)
0.030
0.50
0.018
0.015
0.90
18.95
10.55
---
0.30
0.1
Bal.
Filler metal
(2209)
0.030
1.50
0.018
0.016
0.90
23.0
9.50
---
3.00
---
Bal.
Figure 1 : Dimensions of impact specimens
Table 2 : Welding parameters for experiments
Polarity
Arc voltage (volts)
AC (alternating current)
14
Welding current (amps)
90
Welding speed (mm/sec)
1.4
Heat input (J/mm)
900
Electrode diameter (mm)
2.0
Argon (99.99%)
Shielding gas
Shielding gas flow rate (lt/min)
(a) Base metal (316L)+Filler metal(2209)
10
(b) Base metal (316L)+Filler metal(308L)
Figure 2 : Photographs of impact specimens
Volume 2, Issue 6, June 2013
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 2, Issue 6, June 2013
ISSN 2319 - 4847
3. RESULTS
3.1. IMPACT TOUGHNESS
Charpy impact toughness values of all the joints were evaluated and they are presented in Table 3. The impact
toughness of un welded base metal is 50J. The impact toughness of GTAASS (austenitic stainless steel filler metal)
joints is 40J. Similarly the impact toughness of GTADSS (duplex stainless steel filler metal) joints is 32J. This
indicates that there is 20% increase in toughness value compared to the duplex stainless steel filler metal. Of the two
joints, the GTAASS joints exhibit higher impact toughness values compared to GTADSS joints. The photographs of
pendulum type impact testing machine as shown in figure 3.
Figure 3: Photographs of impact testing machine
Table: 3 Impact properties of base metal and welded joints.
Material
Impact toughness(J)
Base metal (316L)
50
GTAASS (316L+308L)
40
GTADSS (316L+2209)
32
3.2 FRACTURE SURFACE
The fractured surface of impact specimens of welded joints was analyzed by SEM to reveal the surface morphology.
The tested weldments after fractured surface impact specimen photographs as shown in figure 4(a) and 4(b).
Figure 4(a) Photograph of impact after fracture (316L+308L)
Figure 4(b) Photograph of impact after fracture (316L+2209)
Volume 2, Issue 6, June 2013
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 2, Issue 6, June 2013
ISSN 2319 - 4847
Figure 5 displays the fractographs of impact specimens. The impact fracture surfaces of GTAASS joints (Fig.5(a)) and
GTADSS joints (Fig.5(b)) shows ductile fracture. An appreciable difference exists in the size of the dimples between
GTAASS and GTADSS joints. Elongated and fine dimples are seen in GTADSS joints, whereas fine dimples are seen
in GTAASS joints. Large number of fine dimples is seen in GTAASS joints compared to GTADSS joints. Since fine
dimples are a characteristic feature of ductile fracture, the GTAASS joints have shown higher ductility compared to
GTADSS joints (Table 3).
5(a)
5(b)
Figure 5: SEM fractographs of impact specimens (a) GTAASS (b) GTADSS
4. CONCLUSION
The present investigation provided a effect of filler metal such as austenitic stainless steel (ASS) and duplex stainless
steel (DSS) with austenitic stainless steel (316L) using gas tungsten arc (GTA) welding. The main conclusions are:
1. Of the two filler metals used, the joint fabricated by ASS filler metal showing 20% higher impact toughness
compared to the joints fabricated by DSS filler metals.
2. The fracture surface morphology, fine dimples characteristic of ductile fracture, the amount of fine dimples are more
in GTAASS joints when compared to GTADSS joints, hence, GTAASS joints have shown higher ductility compared to
GTADSS joints.
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[9.] S.Azuma, K.Ogawa, Duplex stainless steel excellent in corrosion resistance, Applied Thermal Engineering 18 (6)
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AUTHOR
N.V.Amudarasan was born in Attur, Tamil Nadu, India in 1974. He received his bachelor degree in
Mechanical Engineering from Madras University, Tamil Nadu and Master degree in Production Engineering
from Annamalai University, Chidambaram,Tamil Nadu, India. He is presently a research scholar in the
Department of Mechanical and Production Engineering, Sathyabama University. He has fifteen years of
teaching experience. He is a member in ISTE, IWS and IIPE.
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