Controlling chloride induced stress corrosion cracking of AISI 316L stainless steel by application of buffing

Abstract

This paper presents the effect of buffing on the stress corrosion cracking (SCC) resistance of machined surfaces of AISI 316L stainless steel (SS). Surface finishing operations are known to lower the SCC resistance of austenitic stainless steels and yet are unavoidable. AISI 316L SS samples were given for different surface finishing operations like turning, milling and grinding. The surface roughness in each case was determined using stylus profiler (contact mode). Lattice strain and phase changes were detected by X-ray diffractometry (XRD) studies. SCC susceptibility has been studied before and after surface buffing operation by exposing to magnesium chloride hexahydrate solution (MgCl2.6H2o) as per ASTM standard procedure G36 for 3h. Microstructural characterization before and after SCC tests were characterize by using field emission SEM (FESEM). Results highlights that AISI 316L SS in turned, milled, and ground condition were highly prone to Cl induced SCC. But on the application of buffing, the SCC resistance of the samples was enhanced and no cracking was observed. Crack enhancement was due to a) reduced surface roughness b) minimum plastic strain and c) high compressive residual stresses generated during buffing operation.