Numerical study on mechanical erosion behaviour of the burning-free Al2O3–C bottom nozzle during casting

Abstract

The burning-free bottom nozzle is a novel component for accurately controlling the molten steel flow during the casting steel process. The effect of the thermal mechanical behaviour of burning-free Al2O3–C bottom nozzle materials under extreme temperatures during casting on the thermally induced failure was investigated. First, the high-temperature dynamic Young's modulus and thermal expansion of the bottom nozzle materials were tested in the temperature range of 300–1473 K. A composite material constitutive model, a thermal conductive model and the concrete damage plasticity model (CDP) were adopted to examine the mechanical erosion behaviour of the Al2O3–C bottom nozzle in the casting process based on Finite Element Method (FEM). Results shown that the area near the core of the bottom nozzle was at a high temperature and under tensile stress conditions, whereas the edge area restricted by the external steel shell was mainly under compressive stress conditions. Then, the cracking tendency was evaluated, and an optimised bottom nozzle with a composite structure was proposed. The burning-free Al2O3–C bottom nozzle with a composite structure has an advantage in reducing the risks of cracking and extending the service life compared with the nozzle made of homogeneous materials. This work can make a significant contribution to the design of high performance bottom nozzles.