UM  > Faculty of Science and Technology  > DEPARTMENT OF ELECTROMECHANICAL ENGINEERING
Desensitization of austenitic and duplex stainless steels by laser surface melting
Chan W.K.; Kwok C.T.; Lo K.H.; Cheng Z.
2010-06-11
Conference NameThe 3rd Pacific International Conference on Application of Lasers and Optics (PICALO 2010)
Source Publication3rd Pacific International Conference on Applications of Lasers and Optics, PICALO 2010
Conference Date23 – 25 March 2010
Conference PlaceWuhan, China
Abstract

Sensitization is one of the corrosion mechanisms which cause widespread problems in stainless steels, particularly in welded assemblies and improperly heat-treated work pieces heated at 500 to 800°C. As the Cr-rich carbides and sigma phase form, they deplete their neighboring regions of Cr, thereby lowering the Cr contents of the surface oxides over these regions. Once the contents of Cr in the regions adjacent to the carbides drop below 12 wt%, the oxide layers lose their protectiveness. Then the stainless steels will suffer from intergranular corrosion attack. Laser surface melting (LSM) can be easily achieved by melting the surface with a laser beam followed by rapid solidification for homogenizing chemical compositions, desensitization of improperly heated surface (i.e. redisolving the chromium carbides) and even removing surface cracks. In the present study, LSM of austenitic stainless steels (AISI 304, 321 and 347) and duplex stainless steel (AISI 2205) was attempted for desensitization by a 2.5 kW Nd:YAG laser and the susceptibility of the sensitized stainless steels before and after LSM to intergranular corrosion was also evaluated. The degree of sensitisation (DOS) of the stainless steels was determined by the double loop electrochemical potentio-kinetic reactivation method in solution of 0.5 M HSO and 0.01 M KSCN at 25 °C by a potentiostat. The corrosion morphology and surface hardness were also investigated as well. Desensitization of stainless steels was successfully achieved by LSM and their intergranular corrosion resistance was found to be significantly enhanced as reflected by the decrease in DOS due to the low chromium depletion or possible solute segregation at the boundaries.

KeywordIntergranular Corrosion Laser Surface Melting Sensitization Stainless Steels
URLView the original
Language英語English
Fulltext Access
Document TypeConference paper
CollectionDEPARTMENT OF ELECTROMECHANICAL ENGINEERING
AffiliationUniversidade de Macau
First Author AffilicationUniversity of Macau
Recommended Citation
GB/T 7714
Chan W.K.,Kwok C.T.,Lo K.H.,et al. Desensitization of austenitic and duplex stainless steels by laser surface melting[C],2010.
APA Chan W.K.,Kwok C.T.,Lo K.H.,&Cheng Z..(2010).Desensitization of austenitic and duplex stainless steels by laser surface melting.3rd Pacific International Conference on Applications of Lasers and Optics, PICALO 2010.
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