晶粒度对690合金热变形特性的影响

Effect of Grain Size on Hot Deformation Characteristics of 690 Alloy

摘要:

利用物理模拟实验方法对具有不同晶粒尺寸的690合金试样进行热压缩变形实验，变形温度范围为1100~1200 ℃，应变速率分别为0.1, 1, 10 s-1，获得了合金的流变应力数据，并对合金变形后的组织特征进行了分析，建立了包含初始晶粒度参数的本构关系模型。结果表明：晶粒尺寸增大使690合金高温变形时的流变应力增加，发生动态再结晶的临界应变增大，动态再结晶体积分数减小，根据所建立的流变应力本构模型计算出的流变应力值与实验值相近，从而完善了690合金的热变形本构方程

Abstract:

The flow stress behaviors and the microstructure characteristics of 690 alloy with different grain sizes were investigated by isothermal compression tests in the temperature range of 1100~1200 °C and strain rate range of 0.1~10 s-1 on thermo-simulation machine. The flow stress constitutive relationship with initial grain size parameter of 690 alloy was established. The results show that increasing of initial grain size produces higher values of flow stress and the critical strain for the onset of dynamic recrystallization. Dynamic recrystallization volume decreases with increasing of grain size. The flow stress of 690 alloy predicted by the proposed models well agrees with experimental results. Therefore, the constitutive equation of 690 alloy during hot deformation process is improved