Effect of Multi-pass Deformation on Microstructure Evolution of Spark Plasma Sintered Ti-6Al-4V Alloy

In this paper, the microstructure of Ti-6Al-4V alloy sintered by spark plasma was studied by multi-pass of hot compression experiment, and the influence of different thermal deformation parameters (hot compression temperature deformation: 950 degrees C-20% for one pass, 850 degrees C-20% for two passes and 900 degrees C-10%/20%/30% for three passes) was studied. The results show that the dynamic recrystallization characteristic behavior appears in the three deformation passes. The microstructure after the first and second pass deformation is mainly composed of Widmanstatten structure. With the increase of strain rate, the thickness of lamellar alpha decreases gradually. In three pass, the grain boundary alpha phase and the layered alpha phase are twisted and bent when the deformation amount is 10% and 20%, and the deformation amount increases to 30%. The spheroidization of lamellar alpha phase occurs, and the size of beta grain decreases obviously. The content of equiaxed alpha phase and grain size decrease with the increase of strain rate.