Superplastic forming gas pressure of titanium alloy bellows
(1. Department of Plasticity Technology, Shanghai Jiaotong University, Shanghai 200030, China;
2. Department of Materials Engineering, Harbin Institute of Technology, Harbin 150001, China)
2. Department of Materials Engineering, Harbin Institute of Technology, Harbin 150001, China)
Abstract: The complex superplastic forming (SPF) technology applying gas pressure and compressive axial load is an advanced forming method for titanium alloy bellows，whose forming process consists of the three main forming phases namely bulging, clamping and calibrating phase. The influence of forming gas pressure in various phases on the forming process was analyzed and the models of forming gas pressure for bellows were derived according to the thin shell theory and the plasticity deformation theory. Using the model values, taking a two-convolution DN250 Ti-6Al-4V titanium alloy bellows as an example, a series of superplastic forming tests were performed to evaluate the influence of the variation of forming gas pressure on the forming process. According to the experimental results these models were corrected to make the forming gas pressures prediction more accurate.
Key words: superplastic forming; bellows; Ti-6Al-4V; pressure