The Effect of Heat Treatment on the Microstructures and Dynamic Mechanical Properties of Near-β Ti-5553 Alloy
Ti-5553(Ti-5Al-5Mo-5V-3Cr-1Fe) is a new near-β Titanium alloy with some applications as structural components in aircrafts. In this paper, Ti-5553 alloy was heat treated at four different solid solution temperatures: 770°C, 790°C, 830°C and 850°C, followed by the same aging treatment. Quasi-static compressive and tensile experiments as well as Split Hopkinson Pressure Bar (SHPB) compression experiment were carried out to investigate the mechanical properties of Ti-5553 alloy. The microstructure evolutions were characterized using Optical Microscope (OM) and Scanning Electron Microscopy (SEM). The experimental results demonstrated that different microstructures of Ti-5553 alloy were obtained through four different heat treatment procedures. The main microstructures are aα+βb with different volume fractions. Ti-5553 alloy treated at 770°C, with secondary α precipitates embedded in β matrix, behaves the best combination of strength and toughness. In dynamic compression, strain rate hardening effect occurs exclusively in the samples with the Widmanstatten structure and not occurs in other samples.