Abstract: In order to study the differences in microstructure and high temperature properties of different positions of turbine disc forging in GH4706 alloy， comparative analysis of mechanical properties at high temperature were carried out. Detailed experiments included high-temperature tensile property （conducted at the temperature of 400 ℃， 500 ℃， 600 ℃ and 650 ℃）， high-temperature low-cycle fatigue （conducted at the temperature of 400 ℃， 500 ℃ and 600 ℃） and high-temperature stress rupture life （conducted at the condition of 650 ℃/690 MPa and 600 ℃/700 MPa） based on typical service performance requirements. The test results showed that the grain sizes of the hub， spoke and rim varied significantly， with the hub grain size level 4 （average grain size 84 μm）， spoke grain size level 3 （average grain size 120 μm） and rim grain size level 2 （average grain size 183 μm）.The γ′-γ″ composite of the samples in different positions were dispersed in spherical shape. The η phase of hub and plate is in needle shape， with larger size， and distributed parallel to grain boundaries. The η phase of rim precipitates in the shape of short rods with smaller size and dispersed arrangement at grain boundaries. There was no significant difference in high-temperature tensile strength at different locations. However， the samples from hub had excellent low-cycle fatigue performance （4 363 cycle number）， while the tensile plasticity and stress rupture life of rim was the longest （1 259 h）. The study indicated that the variation of microstructure from different positions of turbine disc forging in GH4706 alloy had significant effects on mechanical properties.

Key words: GH4706 Alloy, Turbine Disc, Grain Size, High-temperature Mechanical Properties

摘要： 为了研究GH4706涡轮盘不同部位的组织及高温力学性能差异性，基于典型服役性能要求，开展了400、500、600、650 ℃条件下的高温拉伸，400、500、600 ℃条件下的高温低周疲劳和650 ℃/690 MPa、600 ℃/700 MPa的高温持久寿命对比分析。试验结果表明，轮毂、辐板及轮缘位置的晶粒组织存在显著差异，其中轮毂晶粒度为4级（平均晶粒尺寸为84 μm），辐板晶粒度为3级（平均晶粒尺寸为120 μm），轮缘晶粒度为2级（平均晶粒尺寸为183 μm）。不同部位试样的γ′-γ″复合相均以球状弥散析出。轮毂和辐板位置的η相呈长针状，尺寸较大，且与晶界平行分布；轮缘部位的η相呈短棒状析出，尺寸较小，在晶界的排列比较分散。不同位置的高温拉伸强度无明显差异，轮毂部位的低周疲劳性能最优（4363循环周次），而轮缘部位的高温拉伸塑性和持久寿命最优（1259 h）。GH4706涡轮盘锻件不同部位的组织差异性对其高温力学性能的影响较为显著。

关键词: GH4706合金, 涡轮盘, 晶粒组织, 高温力学性能