Enhancing Workability Through Adjusting Element Content: A Study on the Hot Deformation Behavior of a Modified Titanium Alloy

Abstract

A modified near-α titanium alloy of Ti-5.2Al-3.7Sn-3.6Zr-0.5Mo-0.5Si-0.02C is subjected to hot compression experiment using Gleeble-3800 at deformation temperatures (T) from 940 °C to 1060 °C and strain rates (ε) from 0.01 to 1 s⁻¹. The β-phase transus temperature of this alloy is decreased about 20 °C, which leads to lower deformation temperature. By fine-tuning the contents of Al, Sn, Mo, Ta, and C elements, the machinability of alloy is optimized while maintaining its mechanical properties. According to stress–strain curves, an Arrhenius constitutive model for Ti-5.2Al-3.7Sn-3.6Zr-0.5Mo-0.5Si-0.02C alloy is established with a linear correlation coefficient (R) of 0.9868. The thermal mechanical processing map of the Ti-5.2Al-3.7Sn-3.6Zr-0.5Mo-0.5Si-0.02C alloy reveals its optimal processing parameters, ranging from 980 to 1010 °C, with a strain rate of 0.01 s⁻¹. The instability region of the Ti-5.2Al-3.7Sn-3.6Zr-0.5Mo-0.5Si-0.02C alloy is reduced about 75% compared to that of the Ti60 alloy, and the energy dissipation rates within the processing regions remain at relatively high levels. Combined with the microstructure of the Ti-5.2Al-3.7Sn-3.6Zr-0.5Mo-0.5Si-0.02C alloy, the mechanism of microstructure evolution is discontinuous dynamic recrystallization with a large accumulation of dislocations near the high-angle grain boundaries, which leads to the nucleation of grains occurred discontinuous dynamic recrystallization.