Propagation of stress corrosion cracks of 26Cr-1Mo ferritic stainless steels in a hot chloride solution

Abstract

Austenitic stainless steels have been extensively used in modern process equipment for the chemical industry. However, they have been troubled with the problems of stress corrosion cracking (SCC), pitting and crevice corrosion in chloride environments. The low interstitial ferritic stainless steels containing 26 {approx} 29% Cr and 1 {approx} 4% Mo have proved a practical solution to many chloride SCC problems. These relatively low strength ferritic stainless steels can be made to crack by hydrogen charging. susceptibility to these hydrogen-induced failures is also sensitive to composition and to prior thermal and mechanical treatment. It is the purpose of this paper to examine the hydrogen participation in the crack propagation of 26Cr-1Mo alloys in a hot chloride solution thereby clarifying the failure mechanism of these materials.