Identification of damage evolution during SCC on 17-4 PH stainless steel by combining electrochemical noise and acoustic emission techniques

Abstract

17-4PH martensitic stainless steel samples were tested in a constant load equipment in a hot MgCl2 solution. Stress corrosion cracking was simultaneously monitored by electrochemical noise (EN) and acoustic emission (AE) techniques. During test corrosion mechanisms gradually evolve from localized pitting to stress corrosion cracking until final rupture. By combining the two monitoring techniques it was possible to distinguish between damage stages with a predominant electrochemical contribution and damage stages with a predominant mechanical contribution to crack propagation. The implementation of combined AE and EN measurements is a promising approach for reliable detection of damage phenomena in SCC promoting environment.