Effect of Environmental Factors on Initiation and Propagation during Stress Corrosion Cracking of SUS 301 Stainless Steel in MgCl2 Solutions

Abstract

The effect of environmental factors such as concentration, temperature, pH and dissolved oxygen on the initiation and propagation during stress corrosion cracking of SUS 301 stainless steel in MgCl2 solutions has been investigated by measuring the elongation of specimen throughout the test.It was shown that each of the environmental factors mentioned above gave a remarkable effect on the process of crack initiation: the crack initiation period decreased with increasing concentration and temperature, and with decreasing pH. The dissolved oxygen became necessary to initiate cracks as the concentration and temperature of testing solutions were decreased. The crack was often observed originating at a pit, a corrosion groove along slip trace or a tripple point of grain boundary. Such a crack nucleation was dependent on the environmental factors. On the other hand, the process of crack propagation was mainly affected by the concentration and temperature of testing solutions, and was cosely related to the fracture surface morphology. The susceptibility of intergranular cracking increased with increasing above factors. Furthermore, the both processes of crack initiation and propagation were dominated by the applied stress also.On the basis of the results obtained above, the effect of environmental factors on the process of crack initiation and propagation was discussed.