Effect of tempering on nitrided and deformed austenitic stainless steel

The effect of tempering on nitrided austenitic stainless steel AISI 316 has been studied. Nitrided specimens (with 0.4 wt-%N) were tempered for short times at temperatures up to 900 degreesC and the results show a small effec t on the microstructures and mechanical properties. The strength is consist ent with a Hall-Petch relationship dependent on nitrogen content in solutio n. The effect of tempering has also been studied on cold and hot deformed n itrided specimens. In these cases, tempering had a range of different effec ts on the microstructures and mechanical properties. Specimens that are tem pered before cold rolling showed a continuous decrease in strength as the t empering temperature increased, while specimens cold rolled and then temper ed had a maximum strength at 550 degreesC. Specimens with 0.4 wt-%N subject ed to tempering followed by hot deformation also showed a maximum strength at similar tempering temperatures. The nature of these changes has been ana lysed and mechanisms have been proposed that relate microstructural effects and properties. (C) 2001 IoM Communications Ltd.