On the Importance of Adiabatic Heating on Deformation Behavior of Medium-Manganese Sheet Steels

The effects of adiabatic heating during deformation of a medium-manganese transformation-induced plasticity steel containing 10.1Mn-1.68Al-0.14C-0.2Si (wt.%) processed with initially 57 vol.% retained austenite were investigated over the temperature range from − 60°C to 100°C at strain rates from 0.002 s⁻¹ to 0.2 s⁻¹. Tensile tests were performed on specimens immersed in isothermal baths, which reduced but did not completely eliminate adiabatic heating. The specimen temperature depended on the extent of adiabatic heating, which increased with strain and strain rate. The measured properties primarily reflected the effects of temperature on austenite stability and the corresponding resistance of austenite transformation to martensite with strain. Changes in austenite stability were monitored by measurements of austenite fractions at a specific strain and observation of microstructures after deformation. The results of this study provide a basis to identify input material parameters required for numerical models applicable to sheet metal forming of medium-Mn steels.