Effects of high-temperature oxidation on powder-metallurgy superalloys microstructures and fatigue performance

被引：0

作者：

Zhang L. ^{[1
]}

Yu Z. ^{[1
]}

Chen Y. ^{[2
]}

Zhang L. ^{[1
]}

Jiang R. ^{[1
]}

Tian G. ^{[2
]}

Song Y. ^{[1
]}

机构：

[1] College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing

[2] Science and Technology on Advanced High Temperature Structure Materials Laboratory, Beijing Institute of Aeronautical Materials, Beijing

来源：

Tuijin Jishu/Journal of Propulsion Technology | 2024年 / 45卷 / 01期

基金：

中国博士后科学基金;

关键词：

High-temperature oxidation; Low-cycle fatigue life; Nickel-based PM superalloy; Precipitate phase; Turbine disk;

D O I：

10.13675/j.cnki.tjjs.2207054

中图分类号：

学科分类号：

摘要：

In order to explore the effects of surface oxidation on the low cycle fatigue（LCF）performance for powder-metallurgy（PM）superalloys of turbine discs，the effects of oxidation time on the fatigue properties were studied for both coarse grain（CG）and fine grain（FG）variants of a third-generation nickel-based PM superalloy. The high-temperature pre-oxidation and LCF experiments were carried out at 700 ℃ in air environment. By using SEM and EDS methods，the LCF sample fractures，the structural composition of surface oxide layer and the precipitates phase morphology were characterized to reveal the mechanism of LCF crack initiation. The experimental results show that the thickness of the oxide layer increases with oxidation time，and oxidative intrusion is found in the matrix. The oxidation resistance of CG is better than that of FG in the same oxidation time. The fatigue cracks mainly initiate from the stress concentration area，such as oxidation intrusion and subsurface inclusions，and the LCF lives are affected by the combination of oxidation and inclusions at experimental temperature. The oxide layers show a hierarchical structure after the high-temperature oxidation，as the external layer contains NiO，the middle layer is a mixture of Cr2O3，TiO2 and spinel phase NiCr2O4，and the internal oxide layer comprises of Al2O3. The average size of secondary γ′ phase in CG increased after oxidation，while no significant change of secondary γ′ was found in FG，but long stripes of secondary γ′ were observed near the grain boundaries in both CG and FG after oxidation. It shows that grain boundaries were preferentially destroyed under high-temperature oxidation. © 2024 Journal of Propulsion Technology. All rights reserved.

引用

共 33 条

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