Transactions of Nanjing University of Aeronautics & Astronautics
Effect of Broaching Machining Parameters on Low Cycle Fatigue Life of Ni-Based Powder Metallurgy Superalloy at 650 ℃
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Abstract:
Effects of different broaching machining techniques on fatigue damages are studied. Low cycle fatigue tests at high temperature 650 ℃ in air environment are carried out for specimens with four processing techniques. The roughness characterization method， electron backscatter diffraction （EBSD） and nanoindentation test are used to obtain the surface roughness， residual stress and work hardening， respectively. The wire cut electrical discharge machining （WEDM） specimens exhibit the highest fatigue life of average 80 360 cycle with the lowest surface roughness of 0.226 and residual stress， while specimens machined by blunt tool suffer the lowest fatigue life of average 43 978 cycle， decreasing 45% compared to WEDM ones. SEM results show that fatigue cracks are mainly initiated from the coarse non-recrystallized grains and machining defects. The broaching machining methods and parameters have significant influences on the level of fatigue damages and fatigue lives.
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Project Supported:
This work was supported by the National Natural Science Foundation of China （No.12250710129）， the Natural Science Foundation of Jiangsu Province （No.BK20200450）， the China Postdoctoral Science Foundation （Nos.2023M731823， 2020TQ0144）， and the Fundamental Research Foundation for the Central Universities （No.NS2022019）.
Clc Number:
V216.3
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