The effect of the initial microstructure on the hot workability of a powder metallurgy Ni-based superalloy was investigated in the high-temperature range of 950 °C to 1180 °C and strain rate range of 0.001 to 1.0 s⁻¹. Six samples with different initial microstructures were fabricated by various hot isostatic pressing (HIP) conditions and subsequent treatments such as hot extrusion. The coarse-grained samples exhibited low hot workability regardless of the deformation conditions. In contrast, the hot workability of the fine-grained samples significantly varied depending on the deformation conditions. The hot workability exhibited a peak at the sub-solvus temperature of ~ 1100 °C and decreased at temperatures higher and lower than this temperature. In addition, the hot workability decreased monotonically with increasing the strain rate. The prior particle boundaries (PPBs) acted as cavity nucleation sites and crack paths, especially at lower temperatures and higher strain rates, resulting in early fracture and low hot workability. With decreasing the grain size, the hot workability at the peak temperature improved. The extruded sample with the smallest grain size exhibited the best hot workability, owing to the avoidance of PPB fracture and the acceleration of dynamic recrystallization.

在950°C至1180°C的高温范围和0.001至1.0 s ^-1的应变速率范围内研究了初始微观结构对粉末冶金Ni基高温合金热加工性能的影响。。通过各种热等静压（HIP）条件和后续处理（例如热挤压）制造了具有不同初始微观结构的六个样品。无论变形条件如何，粗粒样品均显示出低的热加工性。相反，细粒样品的热加工性根据变形条件而显着变化。热加工性在约1100°C的亚固溶温度下显示出峰值，并在高于和低于该温度的温度下降低。另外，热加工性随应变率的增加而单调降低。先前的粒子边界（PPB）充当腔形核位置和裂纹路径，尤其是在较低温度和较高应变速率下，导致早期断裂和低热加工性。随着晶粒尺寸的减小，峰值温度下的热加工性提高。由于避免了PPB断裂和加速了动态再结晶，具有最小晶粒尺寸的挤出样品表现出最佳的热加工性能。