Performance Enhancement of Austenitic Stainless Steels Based on the Adjustment of Grain Size by Reversion, Recrystallization, and Grain Growth

The effects of grain size on the properties of AISI 304L and 316L stainless steels were critically discussed. Different grain sizes of 0.5, 2.7, 5.6, 15, 34, 90, and 192 mu m were obtained via cold rolling followed by reversion, recrystallization, and grain growth annealing. Cyclic potentiodynamic polarization tests revealed that the uniform corrosion resistance deteriorated and the pitting resistance improved with grain refinement. Accordingly, a specific range at moderate grain sizes can be recommended to improve the overall corrosion behavior, which was in the range of 5.6 to 15 mu m. Moreover, tensile tests revealed that the optimum strength-ductility balance can be obtained at the grain size of 5.6 mu m in both alloys. Accordingly, the grain sizes of similar to 5 mu m can be considered as the optimum for both the strength-ductility trade-off and the balance between uniform and pitting corrosion resistance. While the uniform corrosion resistances of AISI 304L and 316L stainless steels were comparable, the latter alloy showed better pitting resistance due to the high Mo content, while the former alloy showed better strength-ductility balance due to its high work-hardening ability.