Failure analysis of the 18CrNi3Mo steel for drilling bit

Sheng Xu, Ya Zheng Liu, Le Yu Zhou, Yong Ming Yan, Hong Wu Zhu

Research output: Contribution to journalReview articlepeer-review

5 Citations (Scopus)


The failure cause of the 18CrNi3Mo steel for drilling bit, including inclusions, prior austenite grain size, carburized layers, and morphology of the fatigue fracture, was investigated by optical microscope, quantitative metallography, and scanning electron microscope. Results show that the failure of the drill bit is not related to interior inclusions or the inhomogeneity of the prior austenite grain size distribution. The failure is related to geometrical discontinuities causing stress concentration along the tooth profiles while under effect of continuous twisting and axial impact. Thus, the crack initiates in these areas, and the microstructures of the carburized layer, the transitive layer, and the matrix are all tempered martensite such that the crack propagation cannot be effectively restrained and the crack propagates quickly, causing premature failure of the drilling bit.

Original languageEnglish
Pages (from-to)183-190
Number of pages8
JournalJournal of Failure Analysis and Prevention
Issue number2
Publication statusPublished - 2014 Apr


  • 18CrNi3Mo steel
  • Failure analysis
  • Fatigue crack
  • Fracture


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