Numerical investigation on thermomechanical behavior of alumina–calcium hexaluminate refractories for purging plug

Alumina–spinel refractories used in slit-type purging plugs are susceptible to cross-sectional damage,resulting in a serious mismatch between their service life and that of ladle.Alumina–calcium hexaluminate refractories have gradually become the new trend in purging plug materials with the development of refining technology.The thermomechanical damage of slit-type purging plugs with alumina–calcium hexaluminate refractory was investigated by the thermo-solid coupling simulation.Combined with the polynomial fitting and design of experiments methods,the influence of thermophysical parameters on temperature and thermal stress of alumina–calcium hexaluminate refractories for purging plugs was systematically analyzed.The results show that the maximum thermal stress of the purging plugs appears during the stages of steel transporting and stirring,and the vulnerable parts are located above Y=0.323 m.The thermal conductivity and the coefficient of thermal expansion of the material are the most sensitive parameters to the temperature and thermal stress inside the structure,respectively.The addition of more calcium hexaluminate can relieve the stress concentration and large deformation around the slits.Consequently,when the content of calcium hexaluminate is 47 wt.%and in the form of aggregate-binder,the temperature and thermal stress distribution inside the refractory are optimal,which can effectively improve the service life of the slit-type purging plug.