Failure of Trailer Kingpins Caused by Overheating During Forging
To forged AISI 4140 steel trailer kingpins fractured after 4 to 6 months of service. Fractographic and metallographic examination revealed that cracks were present in the spool-flange shoulder region of the defective kingpins prior to installation on the trailers. The cracks grew and coalesced during service. Consideration of the manufacturing process suggested that the cracks were the result of overheating of the kingpin blanks prior to forging, which was exacerbated during forging by deformation heating in the highly-strained region. This view was supported by results of two types of tensile tests conducted near the incipient melting temperature at the...
T.M. Maccagno, J.J. Jonas, S. Yue, J.G. Thompson, Failure of Trailer Kingpins Caused by Overheating During Forging, Handbook of Case Histories in Failure Analysis, Vol 2, Edited By Khlefa A. Esaklul, ASM International, 1993, p 53–57, https://doi.org/10.31399/asm.fach.v02.c9001302
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