Fatigue Fracture of an 8617 Steel Pilot-Valve Bushing
A pilot-valve bushing fractured after only a few hours of service. In operation, the bushing was subjected to torsional stresses with possible slight bending stresses. A slight misalignment occurred in the assembly before fracture. The bushing was made of 8617 steel and was case hardened to a depth of 0.13 to 0.4 mm (0.005 to 0.015 in.) by carbonitriding. Specifications required that the part be carbonitrided, cooled, rehardened by quenching from 790 deg C (1450 deg F), then tempered at about 175 deg C (350 deg F). Visual examination, hardness testing, and metallographic and microstructural investigation supported the conclusion...
Fatigue Fracture of an 8617 Steel Pilot-Valve Bushing, ASM Failure Analysis Case Histories: Mechanical and Machine Components, ASM International, 2019, https://doi.org/10.31399/asm.fach.mech.c0046195
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