Stress corrosion cracking behavior of PH13-8Mo stainless steel in Cl– solutions

Abstract

The stress corrosion cracking (SCC) behavior of PH13-8Mo precipitation hardening stainless steel (PHSS) in neutral NaCl solutions was investigated through slow-strain-rate tensile (SSRT) test at various applied potentials. Fracture morphology, elongation ratio, and percentage reduction of area were measured to evaluate the SCC susceptibility. A critical concentration of 1.0 mol/L neutral NaCl existed for SCC of PH13-8Mo steel. Significant SCC emerged when the applied potential was more negative than —0.15 VSCE, and the SCC behavior was controlled by an anodic dissolution (AD) process. When the applied potential was lower than —0.55 VSCE, an obvious hydrogen-fracture morphology was observed, which indicated that the SCC behavior was controlled by hydrogen-induced cracking (HIC). Between —0.15 and —0.35 VSCE, the applied potential exceeded the equilibrium hydrogen evolution potential in neutral NaCl solutions and the crack tips were of electrochemical origin in the anodic region; thus, the SCC process was dominated by the AD mechanism.