Study on the dynamic recrystallization model and mechanism of nuclear grade 316LN austenitic stainless steel

• Establish the DRX mathematical models of nuclear grade 316LN stainless steel
• Determine the DRX mechanism of this steel
• Subgrains are formed through dislocations polygonization.
• Subgrains grow up through subgrain boundaries migration and coalescence mechanism.
• DRX nucleation performs in grain boundary bulging mechanism and subgrain growth mechanism.

In this study, the dynamic recrystallization behaviors of a nuclear grade 316LN austenitic stainless steel were researched through hot compression experiment performed on a Gleeble-1500 simulator at temperatures of 900–1250 °C and strain rates of 0.01–1 s− 1. By multiple linear regressions of the flow stress-strain data, the dynamic recrystallization mathematical models of this steel as functions of strain rate, strain and temperature were developed. Then these models were verified in a real experiment. Furthermore, the dynamic recrystallization mechanism of the steel was determined. The results indicated that the subgrains in this steel are formed through dislocations polygonization and then grow up through subgrain boundaries migration towards high density dislocation areas and subgrain coalescence mechanism. Dynamic recrystallization nucleation performs in grain boundary bulging mechanism and subgrain growth mechanism. The nuclei grow up through high angle grain boundaries migration.