Stress Corrosion Cracking Susceptibility and Cracking Criteria of 13 Cr Martensitic Stainless Steels in Neutral Chloride Solution at Room Temperature

Abstract

Hydrogen embrittlement of 13Cr martensitic stainless steel was evaluated in 3% NaCl solution at room temperature using slow strain rate technique (SSRT) and step loading constant load SCC test with simultaneous electrochemical measurements. Under SSRT conditions pits formed during plastic deformation may become the crack initiation site and dissolution of newly created slip steps causes enrichment of the solution in the pit, and thus providing the environment dispensable for hydrogen embrittlement cracking. Hydrogen embrittlement susceptibility represented by I_SCC increases with increasing hardness of the steel and decreasing crosshead speed. However hydrogen embrittlement susceptibility disappears at hardness lower than HV 235. Susceptibility index determined by step loading SCC test (σ_B-σ_SCC)/σ_B relates well with I_SCC. This relation is quite useful for determining the design stress of 13Cr martensitic stainless steel components. Furthermore modified AISI414 stainless steel (Ni and Mo addition) exhibits a slightly higher resistance against hydrogen embrittlement.