Softening Mechanisms and Microstructural Evolution in a Low Stacking Fault Energy Material Between Warm and Hot Working Temperatures

A low stacking fault energy material is subjected to warm working as well as hot working, i.e. in the temperature range 873 K (600 °C)–1173 K (900 °C). The evolution of microstructure is quantified using average grain size and grain size distributions. The microstructural transitions resulting from continuous dynamic recrystallization and discontinuous dynamic recrystallization are examined. The resultant softening is studied using macro- and micro-indentation experiments. The applicability of empirical relations between hardness and microstructural parameters is critically examined. The SFE at each of these temperatures is evaluated using a thermodynamic model and correlated with the softening mechanism.