Effect of rapid resistance heating and forming process on Ti–Nb–Zr–O high-elastic titanium alloy
摘要
The isothermal hot forming of high-elasticity titanium alloy thin-walled components often suffers from significant elastic loss. This study investigates the novel Ti–35Nb–2Zr–0.3O (Ti3523) high-elasticity titanium alloy, focusing on the effects of rapid resistance heating (RRH) compared to traditional muffle furnace heating (MFH) on its microstructure and mechanical properties via EBSD and tensile tests. The results show that RRH at a high heating rate (~45 °C/s) effectively suppresses grain coarsening and minimizes dislocation annihilation. Following air cooling, the yield strength of the alloy decreased to 503.01 MPa for RRH-treated specimens, while 405.49 MPa for MFH-treated specimens compared to the original cold-rolled sheet with a yield strength of 754.25 MPa. Additionally, RRH promoted a higher martensitic α′′ transition, leading to lower elastic modulus (40.62 GPa). After aging treatment, the RRH-treated specimens exhibited precipitation of a high-strength α phase, leading to significant improvement of yield strength (755.63 MPa) and elastic modulus (70.39 GPa). The elastic performance of RRH-treated specimens (Ur = 4.056 MPa) was better than that of the MFH-treated specimens (Ur = 3.333 MPa) and close to the performance of the original sheet (Ur = 4.577 MPa). With the identical heating method (RRH), higher heating rates can preserve the high elasticity of the original sheet. Building upon these findings, the hot forming process of the Ti3523 alloy was further explored. The results revealed that dynamic recrystallization process occurs more completely in the alloy after forming and aging under the RRH process, leading to a 70.72% increase in resilience modulus compared to the original cold-rolled sheet. Due to the dynamic recrystallization, the dislocation density decreased from 6.94×1014/m2 to 6.63×1014/m2 and the proportion of dynamically recrystallized grains increased from 28% to 48.1% after aging treatment. This rapid heating and high-temperature forming method offers a promising technical route for manufacturing advanced aerospace components.