Abstract: The NiCrBSi alloy coating is deposited on steel (AISI 1045) substrates using supersonic plasma spraying technique. The overall structure of the coating is densification and contained a small amount of micro-defects. Rolling contact fatigue (RCF) life of the coating is investigated using a ball-on-disc tester under 1.86 GPa contact stress, and 1 500 r/min rotation velocity. Obtained that the contact fatigue lifetime of coating is 9.0×105 cycle, map of Weibull distribution failure probability is plotted as well. And the failure probability of random cycle is achieved by this Weibull plot under identical work condition. Coating’s residual stress at stage of fatigue life is measured by the X-ray equipment. The results show that the residual stress changed by tensile stress into compressive stress when contact fatigue tests start，and the stress rises slowly in the first half of fatigue process while increases sharply in the following procedure, which makes the mid-stage became the critical point of fatigue failure process. Following this law, fatigue stage of coating can be determined, and the catastrophic failure of coating can be prevented effectively.

Key words: Contact fatigue life, Plasma spraying, Residual stress, Weibull distribution