双性能涡轮盘用超细晶坯料制备工艺基础研究

摘要:

在变形温度为1130 ℃、模具温度为1000 ℃的近等温条件下，通过反复多方向变形工艺获得超细晶粉末高温合金坯料，平均晶粒直径约为3 μm，其室温和750 ℃屈服强度分别高达1470和1140 MPa。利用OM、SEM和TEM对不同状态坯料进行微观组织观察。结果表明：在反复多方向变形的较大累积变形量的作用下，促发多次完全再结晶是粉末高温合金组织充分细化的直接原因。对比HIP态原材料，细晶态粉末高温合金的晶界洁净度更高、厚度更薄，微空洞等体积缺陷更少，并且有细小的第三级γ′相弥散分布于基体之中。

Abstract:

Ultrafine-grained PM superalloy billet with approximate grain size of 3 μm was prepared by multiple forging under the near isothermal condition of 1130 oC deformation temperature and 1000 oC mould temperature, and the yield strengths at room temperature and 750 oC reach 1470 MPa and 1140 MPa, respectively. Otherwise, the microstructure evolution was observed by OM, SEM and TEM. The results indicate that the full refinement of the PM superalloy is directly caused by the entire recrystallization of many times resulting from great accumulative deformation of multiple forging. Compared with HIPed original material, the ultrafine-grained PM superalloy possesses fine tertiary γ' phases dispersed in the matrix, cleaner and thinner boundary, which present less defects such as micropores.