Hot Deformation Behavior of Pre-deformed Mo-0.3La Alloy
The hot deformation behavior of pre-deformed Mo-0.3La alloy was studied on the Gleeble-3500 thermal-mechanical simulator at 973-1273 K with the deformation rate of 0.001-0.1 s-1 and the true strain of 60％,and the constitutive equation was established by hyperbolic sine model with Zene-Hollomon parameter.The results show that the dynamic recrystallization characteristics of the true stress-true strain curves are observed.Pre-deformed Mo-0.3La alloy exhibits work hardening at high strain rate of 0.1 s-1 or low temperature of 973 K,and dynamic recrystallization is significant at low strain rate of 0.001 and 0.005 s-1 at 1273 K.The high angle grain boundary of the pre-deformed alloy is 31.65％.After redeformation,the high grain boundary fraction decreases to 17.14％with few recrystallized grains(6.08％).With the increase in deformation temperature,the fraction of high angle grain boundaries and recrystallized grains increases.Calculated by the constitutive equation,the deformation activation energy Q is 287.08 kJ/mol,and the stress exponent n is 14.40.The average relative error between the theoretical stress calculated by the constitutive equation and experimental results is only 3.25％.
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