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基于位错演化规律量化研究了高温变形过程中的加工硬化行为。通过分析Kocks-Mecking和Estrin-Mecking模型在高温变形加工硬化阶段的适用性,发现两种演化模型在动态软化临界条件处发生转换。通过不同变形条件下TC18钛合金热模拟压缩实验,分析不同参数条件下3个硬化阶段的变化规律。整合Kocks-Mecking和Estrin-Mecking模型,研究高温变形加工硬化阶段硬化率对流变应力的响应机制。根据位错增殖系数特点,分析低应力区应力稳态波动的原因及随变形条件不同而出现的变化规律。并由模型中的位错湮灭系数来量化硬化率变化对变形参数的依赖。最后根据高温变形硬化软化的并发性,结合两种演化模型研究高温变形加工硬化行为的阶段性特点。
The work hardening behavior during high temperature deformation was quantitatively studied based on the law of dislocation evolution. By analyzing the applicability of Kocks-Mecking and Estrin-Mecking models in high temperature deformation and work hardening stage, it is found that the two evolution models are transformed at the dynamic softening critical condition. Through the thermal simulation compression experiments of TC18 titanium alloy under different deformation conditions, the variation regularities of three hardening stages under different parameters were analyzed. The Kocks-Mecking and Estrin-Mecking models are integrated to study the response mechanism of the hardening rate to the flow stress at high temperature during work-hardening. According to the characteristics of dislocation multiplication coefficient, the reasons for the steady-state stress fluctuation in low stress zone and the variation rules that occur with different deformation conditions are analyzed. The dislocation annihilation coefficient in the model was used to quantify the dependence of the hardening rate on the deformation parameters. Finally, according to the concurrence of high-temperature deformation and softening softening, combining two evolution models to study the stage characteristics of high-temperature deformation and work hardening.