Why Post-Weld Heat Treatment of 13Cr Stainless Steels is Critical

Type 13Cr martensitic stainless steels widely used in oilfield casing and tubing have high hardenability, which creates a hard heat-affected zone microstructure. Post-weld heat treatment (PWHT) is applied to recover the alloy’s limited resistance to sulfide stress cracking. However, the relatively high strength of 13Cr stainless steel grades (specified minimum 80 to 110 ksi yield) requires tempering temperatures that limit the maximum applied PWHT temperature without compromising the material’s strength. This article1 presents the welding procedure qualification of 13Cr grades and experimental work performed to determine how PWHT affects the yield strength of 13Cr grades and its impact in oilfield environments.