Rolling contact fatigue

{{Short description|Deformation mechanism}}

File:Rolling contact fatigue.jpg, including bearing element and inner ring{{Cite journal |last1=Curd |first1=M. E. |last2=Burnett |first2=T. L. |last3=Fellowes |first3=J. |last4=Donoghue |first4=J. |last5=Yan |first5=P. |last6=Withers |first6=P. J. |date=2019-08-01 |title=The heterogenous distribution of white etching matter (WEM) around subsurface cracks in bearing steels |journal=Acta Materialia |volume=174 |pages=300–309 |doi=10.1016/j.actamat.2019.05.052 |bibcode=2019AcMat.174..300C |issn=1359-6454|doi-access=free }}|292x292px]]

Rolling Contact Fatigue (RCF) is a phenomenon that occurs in mechanical components relating to rolling/sliding contact, such as railways, gears, and bearings.{{Citation |last1=Kapoor |first1=Ajay |title=Rolling Contact Fatigue (RCF) |date=2013 |pages=2904–2910 |editor-last=Wang |editor-first=Q. Jane |url=https://doi.org/10.1007/978-0-387-92897-5_287 |access-date=2024-03-14 |place=Boston, MA |publisher=Springer US |language=en |doi=10.1007/978-0-387-92897-5_287 |isbn=978-0-387-92897-5 |last2=Salehi |first2=Iman |last3=Asih |first3=Anna Maria Sri |editor2-last=Chung |editor2-first=Yip-Wah |editor2-link=Yip-Wah Chung |editor-link=Q. Jane Wang |encyclopedia=Encyclopedia of Tribology}} It is the result of the process of fatigue due to rolling/sliding contact.{{Cite web |title=Rolling Contact Fatigue – About Tribology |url=https://www.tribonet.org/wiki/rolling-contact-fatigue/ |access-date=2024-03-14 |language=en-US}} The RCF process begins with cyclic loading of the material, which results in fatigue damage that can be observed in crack-like flaws, like white etching cracks. These flaws can grow into larger cracks under further loading, potentially leading to fractures.{{Citation |last=Kang |first=Young Sup |title=Rolling Bearing Contact Fatigue |date=2013 |encyclopedia=Encyclopedia of Tribology |pages=2820–2824 |editor-last=Wang |editor-first=Q. Jane |url=https://doi.org/10.1007/978-0-387-92897-5_375 |access-date=2024-03-14 |place=Boston, MA |publisher=Springer US |language=en |doi=10.1007/978-0-387-92897-5_375 |isbn=978-0-387-92897-5 |editor2-last=Chung |editor2-first=Yip-Wah |editor2-link=Yip-Wah Chung |editor-link=Q. Jane Wang}}

In railways, for example, when the train wheel rolls on the rail, creating a small contact patch that leads to very high contact pressure between the rail and wheel. Over time, the repeated passing of wheels with high contact pressures can cause the formation of crack-like flaws that becomes small cracks. These cracks can grow and sometimes join, leading to either surface spalling or rail break, which can cause serious accidents, including derailments.

RCF is a major concern for railways worldwide and can take various forms depending on the location of the crack and its appearance. It is also a significant cause of failure in components subjected to rolling or rolling/sliding contacts, such as rolling-contact bearings, gears, and cam/tappet arrangements.{{Cite web |last=Ahmed |first=R. |title=Rolling Contact Fatigue |url=https://home.eps.hw.ac.uk/~mcera/Publications/Books/ASM-Handbook.pdf |website=Heriot-Watt University }} The alternating stress field in RCF can lead to material removal, varying from micro- and macro-pitting in conventional bearing steels to delamination in hybrid ceramics and overlay coatings.