Formability and microstructure analysis of TiBw/TA15 composites sheet with superplastic tensile and gas bulging tests

Discontinuously reinforced titanium matrix composites (DRTMCs) are promising structural materials that are used at elevated temperatures ranging from 600 to 700 °C. In this study, the superplastic formability of the TiBw/TA15 DRTMCs sheet was investigated through high-temperature tensile and hot gas bulging tests. The DRTMCs sheet demonstrated excellent superplastic formability. In tensile testing, the elongation was observed at 201% (with a strain of 1.1) at 900 °C and 0.01 s−1 strain rate. In the hot gas bulging tests, the lowest elongation along the major strain direction was about 117% (with a strain of 0.77). During superplastic deformation, the number of holes on both sides of the reinforcing phase along the stretching direction was reduced by controlling the strain rate at a slow level, and better superplasticity was observed. The distribution density and the size of the holes increased as the deformation increased. Based on the hot gas bulging tests, it was suggested that the forming limit curve for hot gas forming of the sheet should be determined according to the thinning curves.