Effect of Surface Hardening Technique and Case Depth on Rolling Contact Fatigue Behavior of Alloy Steels

Lechun Xie, David Palmer, Frederick Otto, Zhanjiang Wang, Q. Jane Wang

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Surface hardening techniques are widely used to improve the rolling contact fatigue (RCF) resistance of materials. This study investigated the RCF resistance of hardened, ground steel rods made from three different aircraft-quality alloy steels (AISI 8620, 9310, and 4140) and hardened using different techniques (atmosphere carburizing, vacuum carburizing, and induction hardening) at different case depths. The RCF life of the rods was determined using a three ball-on-rod rolling contact fatigue test machine. After testing, the microstructures of the rods were examined using metallographic techniques. The stress distributions and plastic deformation zones for the specimens under RCF were calculated using an elastoplastic model for plastically graded materials. Relationships between surface hardness, case depth, and RCF life were investigated. The longest lives were observed for the vacuum-carburized AISI 9310 specimens, and the shortest lives were observed for the induction-hardened AISI 4140 specimens. It is concluded that the most important factors in determining the RCF lives of high-cleanliness surface-hardened alloy steels are (1) the hardness in the region of highest octahedral shear stress (in this case, ∼0.13 mm beneath the surface) and (2) the depth of high hardness (>613 HV), which determines the plastic deformation zone size.

Original languageEnglish (US)
Pages (from-to)215-224
Number of pages10
JournalTribology Transactions
Issue number2
StatePublished - Mar 4 2015


  • Carburizing
  • Case Depth
  • Ferrous Alloys, Steel
  • Hardening
  • Hardness
  • Metallurgical Analysis
  • Optical Microscopy
  • Rolling Contact Fatigue

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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