Effects of Alloy Composition on the Stress Corrosion Cracking Susceptibility of Stainless Steels in High Temperature Chloride Solutions

Abstract

In order to evaluate test methods of the stress corrosion cracking susceptibility of stainless steels, effects of a alloy composition on the susceptibility were examined mainly in chloride solutions of low concentration at temperatures from 150 to 250°C by using three-point loading method, and the results were compared with those in high concentrations. The following results were obtained: (1) Higher temperatures and higher oxygen concentrations increased the stress corrosion cracking susceptibility in 0.13% NaCl solution. The data at 250°C plotting the relationship between Ni and Mo contents showed that 2 to 3% Mo increased the susceptibility of alloys containing less than 35% Ni. (2) The stress corrosion test results in boiling 42% MgCl₂ solution at low and high stress levels corresponded to those in 0.13% NaCl solutions at 250°C containing 8 and 20ppm of dissolved oxygen initially. These correspondences were explained by the stress corrosion mechanism in those solutions. (3) The stress corrosion test results of 18Cr-13 Ni-3Si stainless steels containing 0.02 to 0.07% C and 0.01 to 1.0% Cu in various chloride solutions were influenced by test environments and stress loading methods. However, the stress corrosion cracking susceptibility was generally improved by high contents of carbon and copper.