Shape optimization design of the preform and billet of the forging process based on the microstructure optimization

An optimization design method of the microstructure in forging process is proposed. The optimal objective is to obtain the fine and symmetrical grain size. The optimal object is the preform shape. The grain size sub-objective function, the shape sub-objective function and the whole objective function for the multiple objective function optimization are put forward, respectively. The preform shape is used as the optimal design variable. The steps of the optimization design are given. Using the genetic arithmetic and FEM simulation, the software for optimal design method of the microstructure in forging process based on preform design is developed. The perform design of the cylinder upsetting process realizes the optimization of the final microstructure, and the shape of the preform die is given. The reasonable scope of the H/D ratio of the initial billet is suggested according to the value of the objective function with the different H/D ratio of the initial billets.