Microstructure and Properties of Low-pressure Turbine Blade of K465 Alloy after Thermal Fatigue Test

Zhou Zhongbo; Yang Mingbo; Zhang Jianzhong; Shi Laixin

doi:10.15980/j.tzzz.2022.07.027

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Microstructure and Properties of Low-pressure Turbine Blade of K465 Alloy after Thermal Fatigue Test
Vol. 42, Issue 7, Pages: 921-924(2022)
Published： 2022 ，
DOI： 10.15980/j.tzzz.2022.07.027

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Zhou Zhongbo, Yang Mingbo, Zhang Jianzhong, et al. Microstructure and Properties of Low-pressure Turbine Blade of K465 Alloy after Thermal Fatigue Test. [J]. Special Casting & Nonferrous Alloys 42(7):921-924(2022)
DOI：

Zhou Zhongbo, Yang Mingbo, Zhang Jianzhong, et al. Microstructure and Properties of Low-pressure Turbine Blade of K465 Alloy after Thermal Fatigue Test. [J]. Special Casting & Nonferrous Alloys 42(7):921-924(2022) DOI： 10.15980/j.tzzz.2022.07.027.

摘要

对某航空发动机K465合金低压涡轮叶片在900℃及950℃进行100次冷热循环试验，研究了叶片在热疲劳试验过程中的裂纹萌生及扩展，分析了热疲劳试验后叶片的微观组织及力学性能。结果表明，热疲劳裂纹首先从叶片工艺孔处萌生，垂直于叶片轴向方向扩展，工艺孔及缩松处的应力集中是热疲劳裂纹萌生的主要原因；冷热循环试验后枝晶干γ′相尺寸增大，立方形态γ′相边角变得圆滑不规则，且由于针状二次析出相的析出，叶片的伸长率大幅下降。

Abstract

Through the test at 900 ℃ and 950 ℃ for 100 cooling/heating cycles on the low-pressure turbine blade of K465 alloy an aeroengine

the crack initiation and propagation of the blade during the thermal fatigue test were investigated

and the microstructure and mechanical properties of the blade after thermal fatigue test were analyzed. The results indicate that the thermal fatigue crack is firstly originated from the process hole of the blade and extends perpendicularly to the axial direction of the blade. The stress concentration on the process hole and shrinkage is the main reason for the thermal fatigue crack initiation. After the cooling/heating cycle test

the dimension of γ′ phase in the dendrite arm is increased

and the edges and corners of cubic γ′ phase become smooth and irregular. Due to the precipitation of accicular secondary phase

the elongation of blade is decreased significantly.