Effect of tempering on nitrided and deformed austenitic stainless steel

Abstract

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°C and the results show a small effect on the microstructures and mechanical properties. The strength is consistent with a Hall–Petch relationship dependent on nitrogen content in solution. The effect of tempering has also been studied on cold and hot deformed nitrided specimens. In these cases, tempering had a range of different effects on the microstructures and mechanical properties. Specimens that are tempered before cold rolling showed a continuous decrease in strength as the tempering temperature increased, while specimens cold rolled and then tempered had a maximum strength at 550°C. Specimens with 0.4 wt-%N subjected to tempering followed by hot deformation also showed a maximum strength at similar tempering temperatures. The nature of these changes has been analysed and mechanisms have been proposed that relate microstructural effects and properties.