GH2907合金热变形行为及热加工图

Hot Deformation Behavior and Hot Processing Map of GH2907 Superalloy

摘要:

通过热模拟压缩实验研究了GH2907合金在变形温度为950~1100℃、应变速率为0.01~10s_^-1、变形量为60%条件下的热变形行为,流变应力随着变形温度的升高或应变速率的降低而显著降低；根据Arrhenius方程和Zener-Hollomon参数,计算了热变形激活能Q,建立了GH2907合金的热变形本构方程；根据动态材料模型,确定了GH2907合金在不同应变下的功率耗散图,功率耗散效率η较高的区域位于温度为1050~1100℃,应变速率为0.01~0.03s_^-1范围,在该变形区域内组织发生了明显的动态再结晶现象；基于Preased失稳判据,绘制了GH2907合金在不同应变下的热加工图,流变失稳区位于高温高应变速率区域,即温度为970~1100℃,应变速率为0.6~10s_^-1范围,在该变形区域内动态再结晶晶粒沿着绝热剪切带和局部流动分布。根据GH2907合金热加工图及微观组织分析得到适宜的加工区域是温度为1050~1100℃,应变速率为0.01~0.03s_^-1范围。

Abstract:

The hot deformation behavior of GH2907 superalloy in deformation temperature of 950℃~1100℃, strain rates of 0.01s_^-1~10s_^-1 and deformation degree of 60% was studied by thermal simulation compression experiments. The flow stress decreases significantly as the deformation temperature increases or strain rate decreases; according to the Arrhenius equation and the Zener-Hollomon parameter, the thermal deformation activation energy (Q) can be calculated, and the hot deformation constitutive equation of GH2907 superalloy also is established. On the basis of the dynamic material model, the power dissipation map under different strains of the GH2907 superalloy is obtained. The region with higher power dissipation efficiency (η) is located in the temperature of 1050~1100℃ with strain rates of 0.01~0.03s_^-1, and the microstructure dynamic recrystallization phenomenon also occurs in the deformation region; based on the Preased instability criterion, the hot processing map of GH2907 superalloy under different strains is drawn. The rheological instability zone is located in the high temperature range of 970~1100℃ and high strain rate range of 0.6~10s_^-1. In addition, the dynamic recrystallized grains are distributed along the adiabatic shear band and local flow in this deformation region. According to the hot processing map and microstructure analysis of GH2907 superalloy, the suitable processing area is in the temperature of 1050~1100℃ and strain rates of 0.01~0.03s_^-1.