Interfacial Microstructure and Mechanical Property of TC4/20 Steel Bimetallic Composites Fabricated via Liquid–Solid Composite Casting: Effect of Pouring Temperature

A liquid–solid compound casting method is used for fabricate TC4/20 steel bimetallic composites. Systematic investigations are conducted on the interfacial evolution mechanisms and mechanical behavior under varying pouring temperatures (1490, 1520, and 1550 °C). Microstructural characterization reveals interdiffusion of Fe, C, and Ti elements across the interface, forming an intermediate transition layer containing FeC, FeTi, Fe ₂ Ti, and TiC intermetallic compounds. The interfacial microhardness exhibits temperature‐dependent characteristics: peak values reach 1085.6 HV (1490 °C) and 1024.5 HV (1520 °C), while a remarkable enhancement to 1494.8 HV is achieved at 1550 °C due to intensified compound formation. Shear strength demonstrates a nonmonotonic relationship with temperature, attaining an optimal value of 143.6 MPa at 1520 °C, 9.6%, and 57.2% higher than those at 1490 and 1550 °C, respectively. These findings establish that precise control of pouring temperature within 1490–1520 °C enables effective regulation of elemental diffusion kinetics and interfacial reaction products, ultimately governing the mechanical performance hierarchy of the bimetallic system.