Kinetics of deformation processes in high-alloyed cast transformation-induced plasticity/twinning-induced plasticity steels determined by acoustic emission and scanning electron microscopy: Influence of austenite stability on deformation mechanisms

The austenite stability and the stacking fault energy of high-alloyed metastable transformation-induced plasticity/twinning-induced plasticity (TRIP/TWIP) steels, both depending on the chemical composition, have a strong influence on the deformation processes and stress/strain-induced martensitic phase transformation. Aiming at a better understanding of the kinetics of TRIP/TWIP-assisted plastic deformation, acoustic emission (AE) measurements were performed during room temperature tensile deformation of high-alloyed cast model steels with different austenite stability. The real-time AE investigations were complemented by detailed scanning electron microscopy investigations of deformed microstructures using electron backscattered diffraction to determine the martensitic phase transformation and electron channelling contrast to visualize dislocations and their arrangements. The quantitative AE analysis revealed different AE patterns at different plastic strains, which were correlated with underlying deformation mechanisms and microstructural transformations.