Effect of β Solution Treatment on Microstructure and Dynamic Mechanical Properties of Ti–6Cr–5Mo–5 V–4Al Alloy

Ti–6Cr–5Mo–5 V–4Al alloy (Ti-6554) is a recently developed metastable β alloy. The design objective was to attain an optimal balance of excellent strength and ductility through multicomponent strengthening. This study explores the microstructure and dynamic mechanical properties of Ti-6554 alloy bars treated above the β transformation temperature. Results indicated that the grain size increases with prolonged solution time at 890℃, with accelerated grain growth treated over 60 min. When the bars were solution treated at 890℃, the relationship between average grain diameter and solution time follows \(\overline{D} = 165.6t^{0.449}\) . To prevent undesired grain growth as well as coarsening, the recommended solution treatment for Ti-6554 alloy is at 890 ℃ for 15–60 min. Under dynamic loading, there was notable strain softening observed in the true stress–strain curve of the β phase. Samples with the finest grain size displayed superior performance, while larger grain sizes showed a slight decline in dynamic performance. Despite this, the uniform plastic strain did not show a significant decrease. Additionally, the maximum absorbed energy also remained stable. Within the β grain, twin related structures were observed after dynamic compression deformation, indicating that twinning occurred during dynamic loading. Although twinning did not have a substantial impact on average stress values, it enhanced both uniform plastic strain and the maximum absorbed energy.