GH625镍基合金的高温压缩变形行为及组织演变

Hot compression deformation behaviors and microstructure evolution of GH625 Ni-based alloy

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1000～1200℃、应变速率为10-2～10s-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=635.38kJ/mol,α=0.008404MPa-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0.1s-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1000～1100℃发生部分动态再结晶,当温度达到1200℃时,发生完全动态再结晶,此时平均晶粒尺寸约为22.21μm。

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.