Hot deformation behavior and processing map of CIPed Ti-6Cr-5Mo-5V-4Al mixed alloyed powder compressed at temperatures above the β-transus

In order to investigate the hot deformation behavior and the effects of processing parameters on flow stress and microstructure of powder metallurgy Ti-6Cr-5Mo-5V-4Al alloy in the β phase region, the hot compression tests were carried out in the temperature range of 950°C-1300°C and strain rates of 0.1 s −1 , 1 s −1 , and 10 s −1 . It was found that the alloy exhibits increased flow stress and peak stress to deformation with rising strain rates and decreasing deformation temperatures during high-temperature deformation. Based on microstructural observations, dynamic recovery is the primary deformation mechanism at deformation temperatures below 1050°C, while dynamic recrystallization dominates above 1050°C. Additionally, lower strain rates promote the formation of equiaxed β-phase grains. The Arrhenius constitutive model is developed by calculating material constants, including n , β , α , and Q (256.41 kJ/mol). Two instability regions are identified from the constructed processing map: one ranging from 950°C to 965°C and the other from 1015°C to 1075°C, both of which correspond to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mi>ε</mml:mi> <mml:mo>&gt;</mml:mo> </mml:math> 1 s −1 . These findings provide valuable guidelines for optimizing the hot working process of Ti-6Cr-5Mo-5V-4Al alloy.