Unusual stress-induced martensite transformation in Ti-6Al-4V alloy enabled by solution treatment in the lower α plus β regime

Ti-6Al-4V alloy commonly suffers from low strain hardening capability and limited ductility. The present study proposes a novel pathway for improving its work hardening capacity via simple solution in the virgin lower alpha + beta regime. Systematical investigations on microstructures and mechanical properties were con-ducted to unveil the underlying mechanism. Elemental partitioning occurs between a and beta phases and beta-stabilizers are progressively depleted from beta phases as solution temperature rises. Metastable beta phases (beta(m)) can be created in the range of 550 similar to 700 degrees C and transform into alpha '' martensite during mechanical straining. The unusual stress-induced beta(m) -> alpha'' martensite transformation (SIMT) in Ti-6Al-4V alloy induces three-staged strain hardening and triggers the highly desired transformation-induced plasticity (TRIP) effect. Such merit endows this alloy with an extremely high strain hardening rate of similar to 6.5 GPa and ensures good combinations of strength and ductility. (c) 2023 Elsevier B.V. All rights reserved.

Automated summary

A novel pathway for improving the work hardening capacity of Ti-6Al-4V alloy via simple solution in the virgin lower alpha + beta regime is proposed. Elemental partitioning and depletion of beta-stabilizers occur between alpha and beta phases as the solution temperature rises, resulting in the creation of metastable beta phases that transform into alpha '' martensite during mechanical straining. The stress-induced beta(m) -> alpha'' martensite transformation induces three-staged strain hardening and the desired transformation-induced plasticity effect, providing the alloy with a high strain hardening rate and good combinations of strength and ductility.