SCC evaluation of ultra-high strength steel in acidic chloride solution

Abstract

The stress corrosion crack (SCC) susceptibility of ultra-high strength steel AerMet 100 was investigated by slow strain rate technique (SSRT), tensile with polarization and surface analysis technique. The curves of t_f^Cl/t_f^W-strain rate are divided into three regions: stress-dominated region, SCC-dominated region, and corrosion-dominated region, so as the curves of ɛ_f^Cl/ɛ_f^W-strain rate and t_m/t_f-strain rate. The results of tensile tests with polarization show that the main SCC mechanism of AerMet 100 is anodic dissolution, which controls the corrosion process. The three regions have been discussed according to the relationship between the rate of slip-step formation and the rate of dissolution. Fracture appearances in different environments were analyzed by scanning electron microscopy (SEM). SCC fracture appears as a mixture of intergranular and dimples, while it is totally dimples in the inert environment. The ɛ_f becomes the parameter to predict t_f because the relationship between ɛ_f^Cl/ɛ_f^W and t_f^Cl/t_f^W is a straight line for AerMet 100.

Keywords

ultra-high strength steel / stress corrosion crack / slow strain rate technique / strain rate / anodic dissolution / slip-step formation / dissolution

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