Thermo‐Mechanical Behavior of 46MnVNbS5 Microalloyed Steel during Continuous Steel Casting: Experimental and Numerical Simulation Investigation

The thermo‐mechanical behavior of steel is an intrinsic property of the material that reflects its susceptibility to cracking during the metal casting process. In this study, high‐temperature tensile tests and numerical simulations were conducted to investigate the thermo‐mechanical behavior of 46MnVNbS5 micro‐alloyed steel. Based on experimental and numerical results, the hot ductility of 46MnVNbS5 steel was divided into three temperature zones: a high‐temperature zone (1300 °C to 1150 °C), a middle‐temperature zone (1150 °C to 830 °C), and a low‐temperature zone (830 °C to 700 °C). In the low‐temperature zone, the steel exhibits a mixed fracture mode comprising intergranular brittle fracture and micropore aggregation fracture. In the middle‐temperature zone, the fracture surface displays quasi‐cleavage characteristics. In the high‐temperature zone, fracture occurs along the liquid film at grain boundaries. Numerical simulations indicate that cracking may occur in the movable and segment sectors. Additionally, the brittle temperature range expands during solidification. To mitigate corner cracks caused by excessive temperature reduction, the spray angle in the movable sector may be reduced to elevate corner temperatures. After optimizing secondary cooling spray zones, billet corner temperatures increase. Consequently, thermal stress from temperature gradients diminishes, reducing the incidence of corner cracks.