Processing maps for hot working of commercial grade wrought stainless steel type AISI 304

Abstract

The hot-working behaviour of commercial grade wrought stainless steel type AISI 304 is characterized using processing maps developed on the basis of the dynamic material model and hot compression data in the temperature range 600–1250°C and strain rate range 0.001–100 s –. The material exhibits a dynamic recrystallization (DRX) domain in the temperature range 1000–1200°C at a strain rate of 0.01 s −1. Optimum hot workability occurs at 1100°C and 0.01 s −1, which corresponds to a peak efficiency of 32% in the DRX domain. Finer grain sizes are obtained at 1000°C and all strain rates. In comparison with low interstitial stainless steel type AISI 304 L, the DRX occurs at lower strain rate and temperature. This result is attributed to the strong primary effect of interstitial carbon enhancing the rate of DRX nucleation. Flow instabilities occur in the entire region above the DRX domain. Flow localization occurs in the regions of instability at temperatures lower than 1000°C and ferrite formation is responsible for the instability at higher temperatures.