Grain boundary character distribution and sensitisation behaviour of grain boundary engineered stable austenitic stainless steel (AISI 316L)

Abstract

Thermomechanical processing involving a wide range of strain (5–80%) followed by annealing was applied to a type 316L austenitic stainless steel to encourage grain boundary engineered (GBE) structure. As a result of GBE process, the total length fraction of low Σ coincidence site lattice boundaries increased noticeably in conjunction with different levels of grain growth. The GBE structures resulted in significant decreases in the degree of sensitisation following exposure at 948 K for 20 h and assessment through double loop electrochemical potentiokinetic reactivation tests. Strain of low level (5%) was more effective than medium to high strain in inspiring GBE. The role of grain size on the sensitisation process has also been discussed. Additionally, abnormal grain growth contributes to the optimisation of GBE structure.

Keywords:

• Grain boundary engineering
• Austenitic stainless steel
• Degree of sensitisation
• Abnormal grain growth

Acknowledgement

This work is financially supported by National Natural Science Foundation of China (grant no. 51175023).