Effect of TIG Welding and Manual Metal Arc Welding on Mechanical [603906]

Effect of TIG Welding and Manual Metal Arc Welding on Mechanical
Properties of AISI 304 and 316L Austenitic Stainless Steel Sheets
Alaa Abou Harb1,a *, Ion Ciuca1,b, Robert Ciocoiu1,c, Mihai Vasile1,d,
Adrian Bibis2,e, Bilel Rahali1,f, Ismaiel Al Hawamda1,g
1Faculty of Material Science and Engineering , University Polytechnic of Bucharest , Romania
2Romanian Research & Development Institute for Gas Turbines COMOTI, Romania
a*[anonimizat] , [anonimizat] , [anonimizat] ,
[anonimizat] , [anonimizat] , [anonimizat] ,
[anonimizat]
Keywords : AISI 316L stainless steel, AISI 304 stainless st eel, Mechanical properties, gas
tungsten arc welding, Manual Metal Arc welding.
Abstract. The welding technique used for ASIS 304 and 316L austenitic stainless steel sheets both
with a thickness of 3mm is gas tungsten arc welding (TIG) and manual metal arc welding
(MMA W). Mechanical properties that were verified include : hardness test and tens ile test before
welding and after it. The welding process was done on two types of specimens : with a central hole
and without hole . We concluded that there was a decrease in the properties of tensile for both
specimens with central hole , and 316L had tensi le characteristics better tha n 304 when using the
technique TIG . As for 304, it had tensile characteristics better than 316L when using the technique
MMA W. We also concluded that t he existence of central holes had an influence on the hardness
characteristi cs on both types. The hardness increased in 304 but decreased in 316L. The welding
process also showed that there was no influence of MMA W on hardness on both specimens .
However it showed that there was no influence of TIG on the hardness for 304, but for 316L values
increased.
1. Introduction
Austenitic stainless steels have been widely used in manufacturing pressure vessels, tanks, and
heat exchangers, piping systems, valves and pumps because of their e xcellent mechanical
properties.
However, welding often l eads to low mechanical properties owing to the metallurgical changes
such as micro -segregation, precipitation of secondary phases, presence of porosities, solidification
cracking, grain growth in the heat affected zone (HAZ) and loss of materials by vapori zation [1,2].
Generally speaking, welding is one of the most widely used processes to fabricate stainless steel
structures.
304 is the most commonly used types of austenitic stainless steel and versatile, because it has
good mechanical properties such as susceptibility formation and welding, so this type serves the
industrial sector in a wide range [ 3].
304 stainless steel is a widely used material , as it has superior corrosion re sistance. In this alloy,
18% chromium is added to improve corrosion resistanc e, whereas alloying nickel at 8% is used to
stabilize the austenite matrix [4-7].
Alloy 316L stainless steel is a structural material that has been widely used in many industrial
fields, such as the nuclear, cryogenic , and shipbuilding industries [8 ].
It is developed from alloy 304 / 304L. It is characterized by its excellent mechanical properties,
and it is often called nickel , chromium and molybdenum alloy. This alloy is used in the marine
environment, and at low temperatures. It has an excellent corrosion resistance in the welding
conditions [9].
Our aim was to observe mechanical characteristics variations on welded samples which were
previously tensile tested. Key Engineering Materials Submitted: 2017-02-08
ISSN: 1662-9795, Vol. 750, pp 26-33 Revised: 2017-04-22
doi:10.4028/www.scientific.net/KEM.750.26 Accepted: 2017-04-27
© 2017 Trans Tech Publications, Switzerland Online: 2017-08-23
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans
Tech Publications, www.ttp.net. (#91218950-09/06/17,14:09:31)

The tested samples, stainless steel type 304 and 316L were obtained from steel sheets
(2000×1000×3 mm ) by cutting on longitudinal and tr ansverse direction of the sheet.
On each direction , two specimens were tested: one with 5mm drilled hole and o ne full specimen.
Fig. 1 shows the schematics of the samples used [10, 11 ].
From the tensile tested specimens , the narrowed region s were cut and the remaining parts of
specimens were welded together using two methods: TIG and MMAW, afterwards tensile tested
again.
The results allowed us to compare the mechanical characteristics and find st ressed regions on the
test sam ples and decide which method would be the most convenient.

Fig. 1. Tensile specimens used in research: full speci mens (a)
and specimens with a central 5 mm radius hole (b)
2. Materials and Methods
The chemical compositions of the alloys are shown in Table 1.
Table 1 . Chemical composition of the alloys (%)
Material C Si Mn P S Cr Ni Mo Cu
304 0.018 0.369 1.84 0.014 0.0007 18.29 8.3 0.328 0.415
316L 0.018 0.406 1.88 0.019 0.0029 17.04 9.55 1.85 0.391

The samples were tested in tension using a 300 KN servohydraulic universal testing machine
and, on failed specimens, Rockwell C hardness was determined in 10 points.
The narrow region was removed using a metalographic cutter and the remaining parts of
specimens welded together by TIG and MMAW (welding parameters are shown in table 2).
The welded specimens are tested again, in tension, and after failure Rockwell C hardness
measurements are performed in 10 points .
Table 2. Welding parameters used
Specimens Welding
method Welding
current [A] Shielding gas Welding voltage
[V] Welding
electrode
Full specimens
ELT304 MMAW 80 – 20 – 24 309L -17[10]
ELL304 MMAW 80 – 20 – 24 309L -17
ELT 316L MMAW 80 – 20 – 24 309L -17
ELL 316L MMAW 80 – 20 – 24 309L -17
Specimens with holes
TIGHT304 TIG 80 Argon 20 – 24 308L [10]
TIGHL304 TIG 80 Argon 20 – 24 308L
TIGHT316L TIG 80 Argon 20 – 24 308L
TIGHL316L TIG 80 Argon 20 – 24 308L
Key Engineering Materials Vol. 750 27

Abbreviations used:
– EL – electrode for MMAW,
– T – transverse and L – longitudinal (the sample orientation)
– H – hole presence.
3. Results and Discussion
The Load – Displacement curves of the initial specimens are shown in Fig. 2 and 3 and the bar
charts shown in Fig. 4 and 5 show the comparison of the tensile parameters obta ined from initial
testing.

Fig. 2 . Load – Displacement curves for 304 specimens

Fig. 3. Load – Displacement curves for 316L specimens
28 Materials Research and Application II

Fig. 4 . Tensile strength and yield strength comparison for tested samples

Fig. 5 . Elongation and reduction in area com parison for tested samples
On the failed specimens , Rockwell C hardness tests were performed on the regions depicted in
Fig. 6, the variation being shown in Fig. 7 and Fig. 8.

Fig. 6 . Elongation and reduction in area comparison for tested samples
Key Engineering Materials Vol. 750 29

Fig. 7 . Hardness variation on samples made of 304

Fig. 8 . Hardness variation on samples made of 316L
Then the narrowed /deformed region from the samples was cut using a metallograph ic cutter.
Then they were welded together and tested again. T he load – displacement curves are shown in Fig.
9 and Fig. 10.

Fig. 9 . Load – Displacement curves for 304 & 316L Welded specimens

30 Materials Research and Application II

Fig. 10 . Load – Displacement curves for 304 & 316L welded specimen with hole
The bar charts shown in Fig. 11 and 12 present the comparison of the tensile parameters obtained
from testing for Welded specimens.

Fig. 11 . Tensile strength and yield strength comparison for welded samples

Fig. 12 . Elongation and reduction in area comparison for welded samples
Key Engineering Materials Vol. 750 31

By m aking a comparison between specimens of 304 austenitic stainless steel with and with out
central hole, we notice a variation in hardness: the specimens with the central hole show higher
hardness, sign s of higher strain caused by hardening, and in the regions near the hole high est hard –
ness values can be found. Contrary observations are made for 316L samples regarding the hardness
variation.
On all welded specimens (304 steel), the hardness did not vary consider ably, ranging between
30-35 HRC. But for the welded specimens with hole ( 316L steel ), signs of a slight strain caused by
hardening were noticed.
These are shown in Fig. 13 and 14.

Fig. 13 . Hardness variation on samples made of 304

Fig. 14 . Hardness variation on samples made of 316L
If we compare the results that have been obtained through ten sile curves of specimens before
welding for 304 and 316L stainless steel , we find that a decrease of tensile properties on samples
with hole occurred.
By o bserving the tensile curves of specimens that were welded by MMAW, we find that the 304
stainless steel has tensile properties bett er than 316L stainless steel.
For both 304 and 316L steel welded by MMAW, t ensile properties de creased comparing with
the specimens without welding.
By o bserving the tensile curves of specimens that were welded by TIG, we find that the 316L
stainless steel has tensile properties better than 304 stainl ess steel.
For both 304 and 316L steel welded by TIG, t ensile properties decreased comparing with the
specimens without welding.
By o bserving the welded specimens, we note that 316L stainless steel has the best tensile
properties when using TIG weld ing process , but 304 stainless steel has the best tensile prop erties
when using MMAW process .
We note that contraction occurred in the area of plasticity – elasticity and a reduction in yield
strength after welding.
32 Materials Research and Application II

4. Conclusion
The following conclusions were derived from above experimental results and discussion.
We concluded that there was a decrease in the properties of tensile for both specimens with the
existence of holes.
316L steel has better tensile characteristics tha n 304 when using TIG .
304 steel has better tensile characteristics than 316L when using MMA W.
The existen ce of central holes affected the hardness characteristics of both types of specimens ,
therefor e the hardness increased for 304 but decreased for 316L.
The experiment also showed t hat there was no influence of MMA W on hardness of both types of
samples .
It also show ed that there was no influence of TIG process on hardness for 304, but on the other
hand , these values increased for 316L.
References
[1] H.T. Lee, S.L. Jeng, Characteristics of dissimilar welding of alloy 690 to 304L stainless steel.
Science and Technology of welding and joining 6.4 (2001): 225 -234
[2] H. Jamshidi Aval, A. Farzadi, S. Serajzadeh, A.H. Kokabi, Theoretical and experimental
study of microstructures and weld pool geometry during GTAW of 304 stainless steel. The
International Journal of Advanced Manufa cturing Technology 42.11 (2009), 1043 -1051
[3] www.dm -consultancy.com/TR/dosya/1 -59/h/aisi -340-info.pdf .
[4] S.B. David, A.B. Cheryl. AL 201 HPTM (UNS S20100) Alloy A High Per formance, Lower
Nickel Alternative to 300 Series Alloy. Reprinted with the permission of KCI publishing,
Netherlands (2005 ); 17–20
[5] R. Ionescu , M. Mardare, A. Dorobantu, S. Vermesan, E. Marinescu, R. Saban, I. Antoniac DN
Ciocan , M. Ceausu Correlation Between Materials, Design and Clinical Issues in the Case of
Associated Use of Different Stainless Steels as Implant Materials , Key Engineering Materials ,
583, (2014 ), 41-44
[6] C. Sinescu, L. Marsavina, M.L. Negrutiu, L.C. Rusu, L. Ardelean , M. Rominu, I. Antoniac
F.I. Topala , A. Podoleanu , New metallic nanoparticles modified adhesive used for time
domain optical coherence tomography evaluation of class II direct composite restoration ,
Revista de Chimie , 63, 4, (2012 ), 380 -383
[7] International Stainless Steel Forum (ISSF) Members, New 200 -series Stainless Steel: An
opportunity or a Threat to the Image of Sta inless Steel, Brussels 2005; 1–14.
[8] D. Katherasan, S . Srivastava, and P. Sathiya, Process parameter optimization of AISI 316L
(N) weld joints produced using flux -cored arc welding process, Transactions of the Indian
Institute of Metals 66.2 (2013): 123 -132.
[9] www.sandmeyersteel.com/images/316 -316L -317L -Spec -Sheet.pdf .
[10] International Standard ISO 4136:2001(E), 2001. Destructive Tests on Welds in Metal -lic
Materials – Transverse Tensile Test. (2001)
[11] ISO 6892 -1:2009, Metallic materials – Tensile testing – Part 1: Method of test at room
temperature. (2009)
Key Engineering Materials Vol. 750 33