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Effect of laser surface melting on corrosion behavior of aged duplex stainless steel
W.K. Chan; C.T. Kwok; K. H. Lo
2010-12-27
Conference Name29th International Congress on Applications of Lasers and Electro-Optics, ICALEO 2010
Source Publication29th International Congress on Applications of Lasers and Electro-Optics, ICALEO 2010 - Congress Proceedings
Volume103
Pages588-596
Conference Date27-30 Sept. 2010
Conference PlaceAnaheim, USA
CountryUSA
Abstract

Duplex stainless steels (DSSs) have been widely used as the structural components for chemical industries, oil and gas production and offshore applications due to its outstanding corrosion resistance in chloridecontaining environments. However, depletion of chromium and molybdenum is a well-known problem in DSSs, especially in welded assemblies, hotworked and improperly heat-treated parts heated at temperatures ranging from 500 to 900°C. As the sigma phase forms, it depletes the neighboring regions of Cr and Mo, thereby lowering the Cr and Mo contents of the surface oxides over these regions. Then the DSSs become susceptible to corrosion attack. Laser surface melting (LSM) is a possible route to restore the corrosion resistance of DSSs by melting the surface with a laser beam followed by rapid solidification for homogenizing chemical compositions. Different laser parameters will cause different phase distributions in the DSSs, and hence various corrosion properties may be resulted. In present study, microstructure and corrosion behavior of aged DSS 7MoPlus (UNS S32950) were investigated in 3.5% NaCl solution at 25 oC before and after LSM. By LSM, the corrosion resistance of aged 7MoPlus was found to be significantly enhanced as reflected by the increase in the corrosion and pitting potentials and decrease in corrosion and passive current densities. The improvement in corrosion resistance of the aged 7MoPlus after LSM is mainly attributed to re-dissolution and removal of the σ phase.

KeywordDuplex Stainless Steel Laser Surface Melting Nd:Yag Laser Pitting Corrosion
URLView the original
Language英語English
Fulltext Access
Document TypeConference paper
CollectionDEPARTMENT OF ELECTROMECHANICAL ENGINEERING
AffiliationDepartment of Electromechanical Engineering, University of Macau
First Author AffilicationUniversity of Macau
Recommended Citation
GB/T 7714
W.K. Chan,C.T. Kwok,K. H. Lo. Effect of laser surface melting on corrosion behavior of aged duplex stainless steel[C],2010:588-596.
APA W.K. Chan,C.T. Kwok,&K. H. Lo.(2010).Effect of laser surface melting on corrosion behavior of aged duplex stainless steel.29th International Congress on Applications of Lasers and Electro-Optics, ICALEO 2010 - Congress Proceedings,103,588-596.
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