The hot deformation behavior and 3D processing map of 20Mn23AlV non-magnetic steel

Abstract

The thermal compression simulation experiments were conducted at 850–1050 °C temperature and 0.1–10 s⁻¹ strain rate to obtain the flow stress curves of 20Mn23AlV non-magnetic steel at various rolling temperatures and strain rates. An Arrhenius-type constitutive equation was proposed and the 3D processing map based on dynamic materials model (DMM) was developed. The results indicate that Arrhenius-type constitutive model provides accurate predictions for flow stress curves. Given the large reduction characteristics of the actual hot rolling process for this steel and observation of microstructures, a new concept of the low-ξ region was proposed, optimizing the previous criterion of identifying instability region based on negative ξ values. The low-ξ region in the processing map, which exhibits additional substructures such as low-angle grain boundaries compared to other stability regions, has the potential to evolve into an instability region. Pronounced mixed grain phenomena and substructures have been observed in this area, indicating that processing in this region should be avoided. The low strain rate stability region, approximately located within the temperature range of 880 °C–960 °C and the strain rate range of 0.5 s⁻¹–1 s⁻¹, provided optimal hot processing conditions to achieve desirable microstructure and performance for this steel.