Flow characteristics, ANN-based prediction, 3D processing map, and interface microstructure of titanium/stainless steel bimetallic composite

Abstract

To investigate the hot deformation characteristics, workability, and interfacial microstructure of the titanium/steel bimetallic composite, hot compression simulations were carried out on the TA1/SUS430 composite within the temperatures of 750 °C–1050 °C, accompanied by strain rates spanning from 0.01 s⁻1–10 s⁻1. The hyperbolic sine Arrhenius constitutive equation and back-propagation artificial neural network (BP-ANN) model for flow stresses of this bimetallic composite were developed. 2D and 3D hot processing maps were established to study processability. The results revealed the calculated average activation energy (Q) was 277.9671 kJ/mol. The BP-ANN model demonstrated higher prediction accuracy than the Arrhenius model, with a correlation coefficient (R2) of 0.99947. As the strain increases, the area of the unstable region in the processing map expands, and the failure mode is characterized by the formation of microcracks at the bonded interface. Interfacial exfoliation manifested under elevated temperature and high strain rate deformation conditions. High power dissipation (η) values were observed within the processing parameters of 875°C–950 °C/0.01 s−1-0.03 s−1. The bimetal exhibited superior deformation coordination at low strain rates. TiC predominantly constituted the interface products at lower temperatures, while at higher temperatures, phases containing both Fe and Ti dominated. Furthermore, the deformed steel stratum manifested a pronounced cubic orientation <001>//CD and a less dominant recrystallized γ orientation. This γ texture attenuated progressively with increased deformation temperatures, while the strain rate has less impact.