(北京有色金属研究总院, 北京 100088)
摘 要: 在Gleeble−1500D热模拟机上采用等温压缩实验研究GH625合金的高温压缩变形行为,获得合金在温度为1 000~1 200 ℃、应变速率为10−2~10 s−1的条件下的真应力—应变曲线,并在考虑摩擦和变形热效应的基础上对真应力—应变曲线进行修正。对修正后的峰值应力进行线性回归,得到合金的高温材料常数:Q=635.38 kJ/mol, α=0.008 404 MPa−1, n=3.52。通过非线性回归建立GH625合金包含应变量的高温变形本构模型。在应变速率为0.1 s−1时,随着热变形温度的升高,合金发生动态再结晶的体积分数随之增加,在1 000~1 100 ℃发生部分动态再结晶,当温度达到1 200 ℃时,发生完全动态再结晶,此时平均晶粒尺寸约为22.21 μm。
关键字: GH625合金; 流变行为; 变形热; 本构模型; 动态再结晶
microstructure evolution of GH625 Ni-based alloy
(Beijing General Research Institute for Non-ferrous Metals, Beijing 100088, China)
Abstract:The hot deformation behaviors of GH625 nickel-based alloy were investigated by hot compression tests with Gleeble−1500D simulated machine. The true stress—true strain curves in the temperature range of 1 000−1 200 ℃ and strain rate of 10−2−10 s−1 were obtained. The true stain—stress curves were corrected in consideration of the friction and deformation. The material constants, the activation energy (Q) of 635.38 kJ/mol, α of 0.008 404 MPa−1, and n of 3.52, of high-temperature deformation for GH625 were obtained by the linear regression of peak stress. The constitutive equation of GH625 alloy containing the strain was established through non-linear regression. When the strain rate is 0.1 s−1, the volume fraction of dynamic recrystallization increases with increasing the temperature. The results show that partial dynamic recrystallization can be received when the temperature ranges from 1 000 ℃ to 1 100 ℃, and fully dynamic recrystallized structure can be received when the temperature reaches 1 200 ℃. And the average dynamically recrystallized grain size is about 22.21 μm.
Key words: GH625 alloy; flow behavior; deformation heat; constitutive equation; dynamic recrystallization