Enhancing stress corrosion cracking resistance of machined surface via surface mechanical grinding treatment for AISI 316 L stainless steel

The mechanical properties, microstructures and corrosion resistance of turned, milled and surface mechanical grinding treatment (SMGT) processed surfaces were investigated through the surface stress measurement, microhardness, SEM, TEM, TKD, XRD and electrochemical corrosion analysis. The stress corrosion cracking (SCC) initiation behavior of three types of treated surfaces in boiling MgCl2 solution were assessed and compared. The experimental results indicated that the SMGT processed surface inhibited the SCC initiation at the surface stress as high as 874 MPa. The enhancement of SCC resistance was attributed to the SMGT-induced dense ultrafine-grained (UFG) layer, gradient grain refinement and better corrosion resistance, resulting in the high yield strength and high critical stress of SCC initiation.