Optimization of Steel Microstructure during Lamniar Cooling

Abstract

Optimization techniques, in conjunction with a finite element thermal model, are used in this thesis to optimize the temperature profile (i.e. cooling rate and coiling temperature) of a steel skelp during laminar cooling. Optimization parameters include skelp velocity, laminar cooling bank configuration, as well as side-spray conditions. The optimization techniques include two stochastic optimization methods (Genetic Algorithms and Particle swarm optimization) and one deterministic method (The branch-and-bound). A comparison between optimization methods showed that the branch-and-bound method can achieve global optimum faster than the stochastic techniques. The branch-and-bound method was used to set the coiling temperature, using three different cooling strategies (early, late and constant cooling), to reach the specified coiling temperature (550°C). Also the temperature profile optimizations was done, in order to maximize volume of the steel strip, which cool through a desired zone in Continues cooling transformation diagram, was done using branch-and-bound method.