【摘要】 高温热处理冷却过程往往会对高温合金的组织性能产生明显影响。为分析在相同热处理制度下，采用真空气淬炉处理(通气炉冷)的K4800合金试样，相比实验室马弗炉空冷试样在800℃下屈服强度降低96 MPa的原因，通过控制冷速，研究了高温时效处理(1080℃)过程中的冷速对合金γ′相析出状态与力学性能的影响。结果表明：随着冷速由空冷至炉冷逐渐降低，合金中的一次γ′相平均尺寸由307 nm增大至505 nm,二次γ′相平均尺寸则先由48 nm增大至105 nm,随后再次下降；当二次γ′相尺寸由48 nm增至80 nm,合金的显微硬度降低34 HV1,这说明K4800合金性能对热处理冷速较为敏感，真空气淬炉试样高温力学性能降低的原因主要为一次时效后冷速过低，二次γ′相的尺寸增大、数量减少所致。更多还原

【Abstract】 The cooling process of high temperature heat treatment often has a significant impact on microstructure and properties of superalloys. In order to analyze why the yield strength of K4800 alloy treated in vacuum gas quenching furnace(gas-cooled) under the same heat treatment process is reduced by 96 MPa at 800 ℃ compared with that of the sample air-cooled in laboratory muffle furnace, by controlling the cooling rate, the effect of cooling rate during high temperature aging treatment(1080 ℃) on the γ′ phase precipitation behavior and mechanical properties of the alloy was studied. The results show that with the cooling rate decreasing from air cooling to furnace cooling, the average size of primary γ′ phase in the alloy increases from 307 nm to 505 nm, while the average size of secondary γ′ phase first increases from 48 nm to 105 nm and then decreases again. When the size of secondary γ′ phase increases from 48 nm to 80 nm, the microhardness of the alloy decreases by 34 HV1, which indicates that the properties of the K4800 alloy are sensitive to the cooling rate during heat treatment. The main reason for the reduction in high temperature mechanical properties of samples treated in vacuum gas quenching furnace is that the cooling rate after primary aging is too low, leading to an increase in the size and a decrease in the number of secondary γ′ phases.更多还原