Micro Structure Development

The strength of any material is dependent on the grain size and percentage of volume fraction recrystallization. In this book, a new approach for controlling micro structure development during hot working process is explained. Here two different methods are employed. One of the approaches is based on the Optimal Control theory and involves the developing of state space models to describe the material behavior and the mechanics of the process. The standard Arrehenious equation of 0.3% carbon steel is utilized to obtain an optimal deformation path such that the grain size should be 26 micrometer and percentage of volume fraction recrystallization should be 1. The plant model is developed and an appropriate optimality criterion is selected to maintain strain, strain rate and temperature. The state-space model together with an optimality criterion is used to control the grain size and percentage of volume fraction recrystallization using LQR method. In the other approach, FLC is employed. The simulation is done on various values for grain size and percentage of volume fraction recrystallization using both the controllers by MATLAB. FLC controller provides better performance than LQR.