Influence of Applied Stress on Stress Corrosion Cracking of Austenitic Stainless Steel

Abstract

Although a number of studies have been carried out on the influence of various factors on the stress corrosion cracking of austenitic stainless steels, only few have been dealt with the influence of applied stress which is one of these factors. The purpose of this paper is to explore the influence of applied stress on the fracture time, the process of stress corrosion and the fracture surface of stress corrosion cracking of austenitic stainless steel in the boiling magnesium chloride solution.
The results indicate that the applied stress influences remarkably on the fracture time and fracture surface as follows:
On the plots of the applied stress versus the fracture time, the threshold stress was observed, above which the logarithm of the fracture time decreased linearly with increasing level of stress and below which it increased remarkably with decreasing level of stress. It was thought that this result was highly connected with the degree of the plastic deformation on the specimen surface.
On the fracture surface under the applied stress of 15kg/mm², the transgranular fractures were observed chiefly and the intergranular fractures only partly in the regions near the center of the specimen cross section, while under the stress of 30kg/mm², the intergranular fractures were observed chiefly and the transgranular ones only partly in the regions near the specimen surface. From these results, the applied stress was considered one of the important factors by which the transgranular fracture was transformed into the intergranular one.