K4169合金热处理组织和性能研究

Study on Heat-Treated Microstructure and Mechanical Properties of K4169 Alloy

利用SEM和EPMA通过对K4169高温合金经不同温度固溶处理后的典型组织观察、Nb元素分布表征和力学性能测试,研究了固溶温度对合金Laves相、γ′′强化相和拉伸、持久性能的影响。结果表明,合金铸态组织中枝晶间析出了大量Laves相和少量MC型碳化物。经1120℃/2h和1135℃/2h处理后,合金中Laves相体积分数逐渐降低,当温度升高至1150℃时,该相基本全部溶于基体。随着固溶温度的升高,Nb元素的显微偏析程度得到显著改善,大量γ′′相在高Nb区呈盘片状析出;同时,合金室温拉伸性能逐渐提高;650℃/620MPa条件下持久寿命则由11h延长至37h和101h。

The influences of solid solution heat treatment temperature on Laves phase, γ′′ phase and mechanical properties of K4169 alloy by means of optical microscope(OM), scanning electron microscope(SEM)and electron probe micro-analysis(EPMA) have been investigated in the current study. The results reveal that a large amount of Laves phases precipitate in the interdendritic region and some carbides with MC type exist in γ matrix in as-cast structures. The amount of Laves phase decreases with increasing solution temperatures, and fully dissolve into γ matrix of alloy with increasing the solution temperature up to 1150℃. The microsegregation of Nb improves distinctly, and some disc-like strengthening phase γ′′ precipitate in the high Nb content region. Meanwhile, the room-temperature tensile strength and ductility increases gradually and the stress rupture life at 650℃/620 MPa is enhanced to 37 h and 101 h from 11 h with increasing solution temperatures.