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Characterization of the effects of hydrostatic extrusion on structure and surface properties of 303 austenitic stainless steel
|Marcin Pisarek 1,2, Maria Janik-Czachor 2, Piotr Kędzierzawski 2, Krzysztof J. Kurzydlowski 1|
1. Warsaw University of Technology, Faculty of Materials Science and Engineering (InMat), Wołoska 141, Warszawa 02-507, Poland
The stability of the passive film formed on austenitic 303 stainless steel in the as-received state and after severe plastic deformation by hydrostatic extrusion (HE) leading to nanostructurisation was investigated in an aggressive environment containing Cl- ions.
TEM and stereological image analysis were used to examine structural changes introduced by HE. The effect of surface oxide film on the corrosion resistance of 303 stainless steel in a borate buffer + 0.1 M NaCl was investigated by potentiodynamic polarization. Surface analytical techniques such as light microscopy, SEM, AES and SAM were used to characterize the morphology, grain size, and chemistry of the surface, including local characterization of nonmetallic inclusions and their surface before and after HE. SAM analysis revealed discontinuities of the passive oxide film on MnS inclusions. TEM and STEM examinations confirm a drastic reduction of grain size, accompanied by a distinct reduction of the size of sulphide inclusions in the HE matrix. These changes in the 303 HE stainless steel are apparently responsible for its reduced pitting resistance compared to the as-received material.
This work was financially supported by the Polish Ministry of Education and Science through grant 3T08C 013 29. Surface characterizations were performed using a Microlab 350 located at the Physical Chemistry of Materials Center of the Institute of Physical Chemistry, PAS and of the Faculty of Materials Science and Engineering, WUT.
Presentation: Poster at E-MRS Fall Meeting 2007, Symposium J, by Marcin Pisarek
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-14 13:14 Revised: 2009-06-07 00:44