为了阐明GH4720Li合金毫米级粗大晶粒再结晶和塑性协调的可行性，对毫米级晶粒的GH4720Li试样在不同的变形参数下(变形温度为1130、1160和1190℃，应变速率为0.001、0.01、0.1和1 s^-1，工程应变为50%)的热变形行为进行研究，并与细晶GH4720Li合金的热变形行为进行对比。结果表明，具有毫米级粗大晶粒的GH4720Li试样对变形温度更加敏感，且在1160~1190℃、0.001~0.01 s^-1的范围内可以获得完全再结晶组织，但综合考虑再结晶和热变形塑性的控制范围后，确定毫米级粗晶GH4720Li合金应在适中的变形温度下以较低的应变速率进行热变形才能获得均匀的等轴晶组织且不开裂，较好的变形工艺为1160℃、0.01 s^-1。

For nickel-based GH4720Li superalloys, fine-grained structures can be obtained via hot deformation in a two-phase area. However, obvious recrystallized grains' coarsening occurs because of the lack of prime γ' pinning grain boundary when hot deformation occurs in a single-phase area. Much attention is directed to the hot deformation of GH4720Li alloys with fine grains. Moreover, several studies have reported the hot deformation behavior of coarse-grained GH4720Li alloys, with maximum grain sizes of several hundred microns. However, only a few studies report about the hot deformation of GH4720Li alloy with millimeter-level coarse grains. Coarse grains recrystallize incompletely and can reduce the hot deformation plasticity of GH4720Li alloy. Thus, to clarify the coordination feasibility between recrystallization and the hot deformation plasticity of GH4720Li alloy with millimeter-level coarse grains, the hot deformation behavior of GH4720Li alloy with millimeter-level coarse grains was investigated under different deformation parameters (deformation temperature of 1130, 1160, and 1190°C; strain rates of 0.001, 0.01, 0.1, and 1 s^-1; and engineering strain of 50%) and compared with the hot deformation behavior of fine-grained GH4720Li alloy. The results show that the GH4720Li sample with millimeter-level coarse grains is more sensitive to the deformation temperature, but the fine-grained GH4720Li alloy is more sensitive to strain rate. The completely recrystallized structure of the GH4720Li sample with millimeter-level coarse grains can be obtained in the range of 1160-1190°C and 0.001-0.01 s^-1. However, a meager strain rate can cause an undesirable and obvious grain growth. After comprehensively combining the recrystallization control range and the hot deformation plasticity of millimeter-level coarse-grained GH4720Li alloy, it was found that the millimeter-level coarse-grained GH4720Li alloy should be thermally deformed at a moderate deformation temperature and a reduced strain rate of 1160^oC and 0.01 s^-1, respectively, to obtain the uniform equiaxed grains structure without cracking, and better deformation.