Fatigue Fracture of AMS 6470 Steel Knuckle Pins
Within about one month, several knuckle pins (AMS 6470 steel failed, and required to have a minimum case hardness of 92 h15N, a case depth of 0.4 to 0.5 mm (0.017 to 0.022 in.), and a core hardness of 285 to 341 HRB) used in engines failed over a range of 218 to 463 h in operation. Visual examination revealed beach marks typical of fatigue cracks that had nucleated at the base of the longitudinal oil hole. Micrographs of sections revealed a remelt zone and an area of untempered martensite within the region of the cracks. However, review of...
Fatigue Fracture of AMS 6470 Steel Knuckle Pins, ASM Failure Analysis Case Histories: Rail and Rolling Stock, ASM International, 2019, https://doi.org/10.31399/asm.fach.rail.c0046238
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