Carburization induced extra-long rolling contact fatigue life of high carbon bearing steel

•For the first time, carburization surface treatment is applied to high carbon bearing steel.•Carburization introduces a gradient structure with plate/rod cementite in 100Cr6.•RCF life of 100Cr6 is significantly enhanced by more than 10 times through carburization.•Enhancement of RCF life is due to a combined effect of retained austenite and plate/rod cementite.