Abstract

The hot deformation behavior of as-cast CoNi-based superalloy was investigated by means of hot compression tests. The corresponding microstructure evolution after hot deformation was examined by optical microscope, as well as the TEM technique. The constitutive equation and processing map as a function of deformation temperature and strain rate were developed. Results show that the efficiency peak of the processing map is 0.38 at the temperature of 1130 °C and the strain rate of 0.01 s⁻¹. The discontinuous dynamic recrystallization (DDRX) related to the strain-induced grain boundary migration (SIBM) is the dominant recrystallization mechanism during hot working. Meanwhile, the DRX also occurs by forming sub-grains around MC carbides and shear band. In addition, the existence of fine γ′ precipitates are found to retard the recrystallization.

Graphic Abstract

中文翻译：

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铸态钴镍基高温合金的热变形行为和再结晶机制

摘要

通过热压缩试验研究了铸态 CoNi 基高温合金的热变形行为。通过光学显微镜以及 TEM 技术检查热变形后相应的微观结构演变。开发了作为变形温度和应变速率函数的本构方程和加工图。结果表明，在1130°C温度和0.01 s ^-1应变速率下，加工图的效率峰值为0.38. 与应变诱导晶界迁移（SIBM）相关的不连续动态再结晶（DDRX）是热加工过程中的主要再结晶机制。同时，DRX 也通过在 MC 碳化物和剪切带周围形成亚晶粒而发生。此外，发现细小的 γ' 析出物的存在阻碍了再结晶。

图形摘要