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

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.