Effect of Deformation Temperature, Strain Rate, and Strain on the Microstructure Evolution of Ti-17 Alloy

This study investigates the effect of deformation temperature, strain rate, and strain on the deformation behavior above and below the beta (beta) transus temperature (T-beta), as well as the alpha (alpha) + beta microstructure evolution, in Ti-17 alloy during deformation and subsequent cooling to room temperature. Dynamic recovery is the dominant restoration mechanism of the beta matrix during hot deformation above and below the T-beta, which leads to the formation of subgrain structure under applied conditions. During deformation at temperatures less than the T-beta, the alpha phase precipitates at beta grain boundaries initially in a globular or film shape (GB(alpha)), followed by the formation of Widmanstatten alpha (W-alpha) plates from the GB(alpha) and inside the beta grains. The alpha precipitation kinetics is accelerated by increasing the deformation strain during deformation at temperatures less than the T-beta. Even at temperatures greater than the T-beta, deformation is found to induce alpha-phase precipitation at beta boundaries. Further, alpha-phase precipitation occurs during slow cooling after deformation, whereas greater deformation strain leads to a decrease in the total alpha-phase fraction because the enrichment of Mo and Cr and the depletion of Al in the beta phase by the formation of W-alpha at higher temperatures stabilizes the beta phase and thus suppresses the subsequent beta -> alpha transformation during cooling.

Automated summary

This study investigates the effect of deformation temperature, strain rate, and strain on the deformation behavior and microstructure evolution in Ti-17 alloy. Dynamic recovery is the dominant restoration mechanism during deformation, while alpha precipitation occurs at beta boundaries during deformation at temperatures less than T-beta.