Influence of Initial Microstructures on Deformation Behavior of 316LN Austenitic Steels at 400-900 °C

Two batches of 316LN steels were processed differently to achieve specific initial microstructures. The influence of the initial microstructures on the deformation behavior of 316LN steels was investigated by tensile testing at 400-900 °C. Both ultimate tensile strength and yield strength of 316LN steels were found to decrease with increasing testing temperature, and the deformation mechanism varied with testing temperature. At 600 °C and below, dynamic recovery and deformation hardening balance each other. At 600-700 °C, dynamic strain aging caused the serrated flow in the hardening rate-strain curves. At 800 °C and above, polygonization and dynamic recrystallization were the main softening mechanism. High density of dislocations in the steel can enhance the yield strength. Dynamic recovery reduced the dislocation density and eliminated its effect on the ultimate tensile strength.