| During gas quenching, the process parameters can be classified as dependent and independent parameters. One of the most important dependent process parameters is the heat transfer coefficient between the component surface and the circulated gas. Investigations have shown that the heat transfer coefficient has significant influence on the quenching results. In this research, the heat transfer coefficient schedule is modeled in terms of both the quenching time and the component geometry, and it is used as design variables to optimize the gas quenching process. Distortion as a result of the quenching process is predominantly due to the temperature gradient and nonuniform phase transformations. The objective is to minimize the distortion. Performance constraints on the residual stress and surface hardness distributions are imposed. The finite element package, DEFORM-HT is used for simulating the quenching process. The response surface method is used to build the relations between the objective function, constraints and the design variables. Once the closed-form equations are obtained, they are used to search for the optimum design point instead of the finite element simulations. This dissertation summarizes the methodology used to optimize the gas quenching process together with several case studies. |
