Effect of Heat Treatment on the Microstructure and Mechanical Properties of Investment Casting Ti-1300 Alloy

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发表日期：

2024年8月8日

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Yuluo Li,
Qiang Liao,
Yang Song,
Yiming Yang

摘要

The application of titanium alloys in military equipment put forward the requirement for higher strength–plasticity matching. Investment casting is a promising method for the efficient and economical processing of titanium alloys. However, research on the investment casting of higher strength–plasticity matching titanium alloys is still limited. This study systematically investigated the microstructure and mechanical properties of investment casting ultrahigh-strength Ti-1300 alloy under different heat treatment methods and process parameters. The results show that the as-cast microstructure of the investment casting Ti-1300 alloy is a coarse Widmanstätten structure, which exhibits a high ultimate tensile strength (UTS) of 1143.0 MPa with elongation (EI) close to 0. After β-solution and single-aging treatments, the UTS decreased and the EI rapidly increased. This is primarily because the width of the α_P phase was significantly increased and the orientation was more random. In addition, the UTS and yield strength (YS) increased with decreasing aging temperature, while the EI remained unchanged. This was attributed to an increase in the α_P phase content. After 880 °C β-solution and 600 °C aging, the investment casting Ti-1300 alloy exhibited optimal strength–plasticity matching, with a UTS of 949 MPa and an EI of 13.5 pct. Based on these results, to further increase the UTS of the investment casting Ti-1300 alloy, β-solution and double-aging treatment processes were designed to investigate the effect of the morphology of the α_s phase on the mechanical properties. The results show that the UTS and YS increase and the EI decreases with decreasing secondary aging temperatures. This was primarily ascribed to the width of the α_s phase decreasing with decreasing secondary aging temperatures. After 880 °C β-solution and 750 °C aging followed by 620 °C aging, the investment casting Ti-1300 alloy achieved high strength–plasticity matching, with a UTS of 1094 MPa and an EI of 7.0 pct.