MICROSTRUCTURAL MODELING AND NUMERICAL ANALYSIS FOR THE SUPERPLASTIC FORMING PROCESS

Abstract

Superplastic forming is a manufacturing process during which a sheet is blow formed into a die to produce lightweight and strong components. In this paper, the microstructural mechanism of grain growth during superplastic deformation is studied. A new model, which considers grain growth, is proposed and applied to conventional superplastic materials. The relationships among the strain, strain rate, test temperature, initial grain size, and grain growth in superplastic materials are discussed. According to the proposed model, theoretical predictions for superplastic forming processes are presented, and comparison with experimental data is given. The new constitutive equation of superplasticity is introduced into a finite element method program to study superplastic blow forming. The effects of the geometric shape parameters of the die on the superplastic blow forming process are investigated, and the inhomogeneity in the thickness distribution of the specimen is analyzed.

Keywords:

• Constitutive equation
• Dislocation creep
• Finite element method
• Geometric shape parameters
• Grain boundary sliding
• Grain growth
• Grain size
• Inhomogeneity
• Microstructural mechanism
• Strain
• Strain rate
• Superplastic forming process
• Temperature
• Tensile test
• Thickness distribution

Acknowledgments