Influence of thermal aging on the SCC susceptibility of wrought 316LN stainless steel in a high temperature water environment

• Aging at non-sensitized temperature can lead to an increase of SCC susceptibility.
• The brittle fracture surface of long-term aged 316LN shows the IGA.
• Kinks and dislocations have been found at GB as well as aging-induced hardening.
• Carbon enrichment on the GB causes IGA and higher SCC susceptibility in aged 316LN.

Influence of thermal aging at non-sensitized temperature on the SCC susceptibility of wrought 316LN at high temperature water was investigated. The SCC susceptibility increases with increasing of aging time, especially over 1000 h. The fracture surface for aged samples shows a mixed mode. In particular, the intergranular attack (IGA) has been found in brittle surface of the long-term aged material (5000 h). Kinks and dislocations at the grain boundary (GB) have been found as well as aging-induced hardening. Carbon enrichment on the GB is believed to be an important cause of IGA and higher SCC susceptibility in aged materials.