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Novel laser surface treatment approach to suppress sensitisation in modified type 316(N) stainless steel weld metal

DSpace at IIT Bombay

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Title Novel laser surface treatment approach to suppress sensitisation in modified type 316(N) stainless steel weld metal
 
Creator PARVATHAVARTHINI, N
DAYAL, RK
KAUL, R
GANESH, P
KHARE, J
NATH, AK
MISHRA, SK
SAMAJDAR, I
 
Subject prior deformation
evolution
alloys
flow
laser surface treatment
laser
stainless steel
sensitisation and intergranular corrosion
 
Description Welded components are subjected to solution annealing heat treatment for achieving full stress relief and restoration of mechanical properties and corrosion resistance. During such heat treatments, optimum cooling rate has to be selected because very slow cooling rate will result in sensitisation and susceptibility to intergranular corrosion whereas fast cooling will result in reintroduction of residual stress. For 316 LN stainless steel which is welded using modified E316-15 electrodes (0.045-0.055%C), critical cooling rate above which there is no risk of sensitisation is 75 K h(-1). This paper presents a novel laser surface treatment which suppresses sensitisation in weld metal, even at a slower cooling rate of 65 K h(-1). Experiments involving laser surface melting were carried out with 150 W average power pulsed Nd:YAG laser and 10 kW CO2 laser, in both continuous wave and pulse modulated (100 Hz) modes. Best results were obtained when surface melting was performed with high frequency pulse modulated CO2 laser beam. The processed weld metal remained unsensitised after solution annealing followed by slower rate of cooling at 65 K h(-1). Numerical simulation study was performed with ANSYS 7.0 software to understand the physical reason behind the difference in sensitisation behaviour of CO2 laser melted specimens under continuous wave and high frequency pulse modulated conditions and the predictions were validated using results of electron backscattered diffraction studies. Weld metal specimens treated with high frequency pulse modulated CO2 laser clearly showed evolution of fine grains near the fusion boundary region which enhanced sensitisation resistance.
 
Publisher MANEY PUBLISHING
 
Date 2011-08-18T05:27:41Z
2011-12-26T12:55:35Z
2011-12-27T05:41:23Z
2011-08-18T05:27:41Z
2011-12-26T12:55:35Z
2011-12-27T05:41:23Z
2008
 
Type Article
 
Identifier SCIENCE AND TECHNOLOGY OF WELDING AND JOINING, 13(4), 335-343
1362-1718
http://dx.doi.org/10.1179/174329308X299931
http://dspace.library.iitb.ac.in/xmlui/handle/10054/9903
http://hdl.handle.net/10054/9903
 
Language en