Rheological Constitutive and Heat Distortion Behavior of High Chromium Cast Iron Powder/Mild Steel Bimetallic

Hot compression experiments on high-chromium cast iron (HCCI) cladded low-carbon steel (LCS) were performed using a Gleeble−3800 thermal simulator at various temperatures and strain rates. A modified high-precision rheological constitutive model and a hot processing map were established. The results indicate that the flow stress values predicted by the model agree well with the experimental data, accurately reproducing the true stress-strain curve, with a correlation coefficient R of 0.9677 and an average absolute relative error (AARE) of 7.94%. Furthermore, the thermal deformation behavior and microstructural evolution at the composite interface were investigated. It was found that C atoms diffused from the HCCI to the LCS, resulting in a ferritic band near the interface on the LCS side. The width of this band increased with temperature, reaching a maximum of approximately 5.67 μm. Finally, based on the hot processing map and microstructural observations, the optimal processing window was determined as T = 1205-1235 °C and ε = 0.01–0.026 s⁻¹.