Investigation into the Rolling Process of 20CrNiMo/Incoloy 825 Composite Materials

This paper is focused on the rolling finite element simulation and experimental study of 20CrNiMo/Incoloy 825 composite materials. Firstly, single-pass rolling finite element simulations of the composite materials were conducted. The effects of rolling pass reduction and rolling speed on the warpage, interface strain difference, and stress of the 20CrNiMo/Incoloy 825 composite materials were evaluated, highlighting an ideal first-pass reduction of 30% and a rolling speed of 0.117 m/s. Based on these results, rolling finite element simulations under total reduction–pass conditions of 65%–3 passes, 75%–4 passes, and 85%–5 passes were conducted on 20CrNiMo/Incoloy 825 composite materials. The rolling process was found to be optimal for a total reduction of 85%–5 passes based on the ratio of the vertical compressive stress experienced by the Incoloy 825-side metal to the yield strength of Incoloy 825 at 1150 °C. Based on the results of single- and multi-pass finite element simulation experiments, microstructural observations and interface analyses were then conducted on the 20CrNiMo/Incoloy 825 composite materials after rolling. The bonding interface of the composite materials was found to be undulating, indicating good composite effects. In addition, Cr, Ni, and Fe at the interface of the composite materials exhibited a steep gradient of change, indicating trace element diffusion with a distance of 8.27 μm in the 20CrNiMo/Incoloy 825 composite materials. Finally, the interfacial bonding mechanism of the 20CrNiMo/Incoloy 825 composite materials was studied, and the results indicate that this mechanism is based on a combination of diffusion and recrystallization bonding mechanisms.