新型优质GH738合金的亚动态(静态)再结晶动力学模型

设计并进行MTS810-25T低周疲劳试验机上的双道次热压缩实验,研究不同初始晶粒尺寸、变形温度、道次间隔保温时间及应变速率条件下新型优质GH738合金的亚动态再结晶动力学,进而结合定量金相分析,建立该合金的亚动态再结晶动力学方程。结果表明：初始晶粒尺寸减小,变形温度升高、道次间隔时间延长、应变速率增大,均可以促进亚动态再结晶的进行,提高再结晶体积分数；而且,提高变形温度和应变速率可以降低亚动态再结晶后晶粒尺寸上的差异,进一步提升组织的均匀程度。进而,结合定量金相及非线性拟合分析,建立了新型优质GH738合金的亚动态再结晶模型,并将所建立模型的预测值和实验值进行了对比分析,符合程度较好,可以满足工程应用要求。

Sub-dynamic (static) recrystallization kinetic model of the new type alloy of high-quality GH738

Series double-pass hot compression experiments were carried out on the MTS810-25T low-cycle fatigue testing machine for the new type alloy of high-quality GH738. The effects of initial grain size, deformation temperature, holding time between passes and strain rate on the evolution of sub-dynamic recrystallization structure of high-quality GH738 alloy were analyzed. Furthermore, combined with quantitative metallography and nonlinear fitting analysis, the sub-dynamic recrystallization models of high-quality GH738 alloy were established. The experimental results show that the decrease of the initial grain size, the increase of the deformation temperature, the extension of the pass interval, and the increase of the strain rate can promote the progress of sub-dynamic recrystallization, and increase the recrystallization volume fraction. Increase the deformation temperature and strain rate can reduce the difference in grain size after sub-dynamic recrystallization, and further improve the uniformity of the microstructure distribution. Based on the experimental results, by using quantitative metallography and nonlinear fitting analysis, sub-dynamic recrystallization models of high-quality GH738 alloy were obtained. The predicted values of the established models were in good agreement with the experimental values, which could meet the actual needs in engineering applications to a great extent.