Microstructure evolution and mechanical properties of Ti-1023 alloy during β slow cooling process

Microstructure evolution and mechanical properties of Ti -1023 alloy during cooling from single-phase region to dual -phase region with the cooling rate of 1 C-degrees/min were systematically investigated. As the final cooling temperature decreased, grain boundary alpha' martensite (alpha'GB), grain boundary alpha phase (alpha GB), Widmanstatten grain boundary alpha phase (alpha WGB), and Widmanstatten intragranular alpha phase (alpha WI) were sequentially precipitated. Correspondingly, mechanical properties and deformation mechanisms of Ti -1023 alloy changed significantly. When the final cooling temperature was higher than 700 C-degrees, tensile curve showed an obvious double -yielding phenomenon with elongation >20%. Whereas the final cooling temperature was lower than 700 C-degrees, and the double -yielding phenomenon disappeared. This was mainly attributed to the fact that beta stability of Ti -1023 alloys was enhanced with the increase of alpha(alpha') precipitated phases. And the room temperature deformation mechanism gradually changed from stress -induced alpha" martensitic phase transformation to dislocation slip. Furthermore, strengthening mechanism of Ti -1023 alloy was analyzed in combination with grain size and precipitated phase effects.