The effect of HIPping pressure on phase transformations in Ti-5Al-5Mo-5V-3Cr

Hot-isostatic-pressing (HIPping) of pre-alloyed powders is an effective, highly material-efficient, novel manufacturing technique for the preparation of near-to-net shape components. However, the effect of pressure during HIPping on the β→α transformation inherent in titanium alloys is not well understood. This effect on phase transformation was investigated on both powder-based and bulk-based Ti-5Al-5Mo-5V-3Cr (Ti-5553). Microstructure characterisation and phase relationships were investigated using scanning electron microscopy and X-ray diffraction methods. The results show that the modest pressure applied in HIPping (100-200 MPa) can influence the α-β phase transformation in Ti-5553. Possible mechanisms related to these changes in phase transformation and microstructure are discussed.