Content area
Full text
ABSTRACT
The aim of this work is to present the corrosion damage mechanism of austenitic stainless steel 304. The C-ring specimens are chosen according to ASTM G-38 to resemble the stress conditions during the applied load. The specimens are immersed in 3.5% wt of NaCl solution. The variable conditions were studied at a fixed stress of 379Mpa and immersions for 720 hours. The stress distribution over the surface of specimens is formulated by means of a finite-element analysis. The result of the finite-element analysis shows that the region that was perpendicular to the shift in the direction of the pressure was subjected to the highest load. Using the potentiodynamic polarisation measurement method and microscopic observation, the corrosion polarisation behaviour of austenitic stainless steel became more active in cases when immersion and stress are applied simultaneously. The stress on the surface of the specimen shows a significant effect on the polarisation mechanism in the analysed area. The result also shows that the locations of pitting corrosion are apparent on the highest stress area. There is useful information to analyse the corrosion behaviour especially for applications under mechanical loading in corrosive environments, it drives the corrosion behaviour to the critical condition.
Keywords: Pitting corrosion; austenitic stainless steel; stress distribution; corrosive environments.
(ProQuest: ... denotes formulae omitted.)
INTRODUCTION
Stainless steels are widely used in manufacturing industries, due to their high strength and corrosion resistance in many environments [1, 2]. However, austenitic stainless steels are essentially iron chromium -nickel ternary alloys containing sixteen to twenty five % chromium and seven to twenty % metal. These alloys area unit is referred to as austenitic since their structure remains a solid solution (FCC, у iron type) at all normal heat treating temperatures. The presence of the nickel, that has an associate degree FCC crystal structure, alters the FCC structure to be preserved under temperature. The high formability of the solid solution stainless-steel is due to their FCC structure. Solid solution stainless steels ordinarily have higher corrosion resistance than Ferritic and Martensitic ones as a result of the carbides being often preserved in a primary solid solution by speedy cooling from an increased temperature, the chromium imparts coating the surface with a thin but extremely dense film of chromium oxide [3]....