Based on a coupled heat and stress model, an artificial intelligence optimisation program was developed to optimise the process parameters in the continuous casting of steel. The program can be used to identify the key factors for the cracks of the strand and obtain the optimum process parameters of continuous casting. The optimisation program contains two models, one is the thermomechanical model developed using the finite difference method, and the other is the optimisation model developed using the subproblem approximation method. The whole program works by automatic iteration between the two models. This study has taken the stress constraint in the solidified shell into consideration when studying the metallurgical constraints. The application of the achieved optimum parameters would make it possible to run the caster at maximum productivity, with minimum cost and fewer defects. After manufacturing verification of this optimisation project, the incidence of cracks has reduced from 8% to 2%, and water consumption in the secondary cooling zone has been decreased by 25%.List of symbols c(T) specific heat, J kg 21 uC 21 f s solid fraction g gravity acceleration, m s 22 H(T) enthalpy, J m 23 k thermal conductivity, W m 21 uC 21 L latent heat of fusion, J kg 21 obj objective function q : latent heat source, W m 23 s m shell thickness at the mould exit, mm t time, s T temperature, uC T centre temperature at metallurgical length point, uC T pouring pouring temperature, uC T surface surface temperature in secondary cooling zones, uC T unbending temperature at unbending point, uC DT max reheating between zones, uC v casting speed, m min 21 WR water flow rate, L kg 21 W sprays water consumption, L min 21 W spray0 mould water consumption, L min 21 W spray1 water consumption in first secondary cooling, L min 21 W spray2 water consumption in second secondary cooling, L min 21 W spray3 water consumption in third secondary cooling, L min 21 x, y, z rectangular coordinates, mGreek symbols r(T) density, kg m 23 r(T) s density of solid, kg m 23 e strain s stress, MPa
