预变形Mo-0.3La合金的热变形行为研究

The Study on hot deformation behavior of Pre-Deformation Mo-0.3La AlloyZhang Xiao1,3,4,Wang Kuaishe1,2,Feng Pengfa3,4,An geng3,4,Bu chunyang3,4,Hu Ping1,2,Xi Sha3,4,Li Jing3,4,Zhou Sha3,4

摘要:

采用Gleeble-3500热模拟机在变形温度为700～1273K、应变速率为0.001～0.1 s-1、真应变为60%的实验条件下，对预变形Mo-0.3La合金的热变形行为进行了研究，并采用包含Zene-Hollomon参数的双曲正弦模型，建立了热变形流变方程。结果表明:预变形Mo-0.3La合金的真应力-应变曲线具有动态再结晶特征，在较低的温度(973K)/较高的应变速率(0.1 s-1)下，表现出加工硬化，在1273K低应变速率(0.001和0.005 s-1)下动态再结晶具有显著性；合金含有31.65%大角度晶界，再变形后大角度晶界减少至17.14%，且存在少量的再结晶晶粒(6.08%)；变形温度升高，大角度晶界和再结晶晶粒增多；由流变方程得到平均变形激活能Q为287.08kJ/mol，应力指数n为14.40，依据流变方程计算出的应力理论值与实际值的平均相对误差仅3.25%。

Abstract:

The hot deformation behavior of pre-deformation Mo-0.3La alloy was studied on the Gleeble-3500 thermal-mechanical simulator at 973～1273K with the rate of deformation 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 in this experimental conditions, the dynamic recrystallization characteristics of the true stress-strain curves are observed. Pre-deformation Mo-0.3La alloy, at high strain rate 0.1 s?1 or low temperature 973K exhibits workhardening, dynamic recrystallization is significant at low strain rates (0.001 and 0.005s-1) of 1273K. The high angle grain boundaries of the pre-deformation alloy is 31.65%. After redeformation, the high grain boundary decreases to 17.14%, and there are a small amount of recrystallized grains(6.08%), with the increase of deformation temperature, high grain boundaries and recrystallized grains increase. Calculated by the constitutive equation, the deformation activation energy Q is 287.08 kJ/mol, and the stress exponent n is 14.40. Using this equation, the average relative error between the theoretical calculations and experimental results is only 3.25%.