Effect of processing parameters on the morphology of α-phase in Ti-۶Al-۴V alloy during the two-step hot deformation

The morphology of the α-phase in titanium alloys considerably affected their physical and mechanical properties. In this research, the effect of applied strain and inter-pass times on the morphology of the α-phase was studied in the two-step hot deformation process. Hot compression tests were performed at ۹۰۰ ºC and ۰.۰۰۱ s-۱ while the strains in the first and second passes were set as (first cycle: ۰.۶ and ۰.۳) and (second cycle: ۰.۳ and ۰.۶) respectively, with various inter-pass times. The work softening parameter obtained from the stress-strain curves showed that the proper time for globularization of α-layers for the first pass strain of ۰.۶ was ۲۴۰ s and for the second strain of ۰.۳ it was ۲۴۰ and ۳۰۰ s. Microstructure results indicated that the first pass strain of ۰.۳ and the inter-pass time of ۲۴۰ s were the optimum conditions for globularization of α layers.

Keywords:

Ti-۶Al-۴V alloy , Two-step hot deformation process , Microstructure