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The impact damage evolution of thermally sprayed WC-Ni coatings was studied under 1-8000 impacts at a fixed load of 10 kN order. With increasing impact number, the accumulative damages of coatings evolve by in-sequence occurrence of WC spallation, coating cracking, and mixed coating/interface cracking accompanied with crack length and width growing. To comprehensively evaluate the coated component performance by observed accumulative damages as the failure criteria, a critical impact number Nc with critical load Lc is proposed for the onsets of different cracking features. The impact resistance is quantified, by Nc(Lcc) for onset of the coating cracking, and Nc(Lcm) for the mixed coating/interface cracking. A subclassification is identified as Nc(Lcm1) and Nc(Lcm2), respectively, for sequential occurrence of the isolated interface cracking and the propagated interface cracking of the penetrated from the coating surface. As the coating thickness is increased from 50 to 200 μm, the impact resistance under a load of 11.1 kN is correspondingly improved with Nc(Lcc) prolonged from 3000 to 4500, and Nc(Lcm1) from 4500 to 5000. In particular, Nc(Lcm2) is 6000 for the 50 μm coating, but no Nc(Lcm2) failure for the 200 μm coating up to 8000 impacts. The impact stress field analysis reveals reduced amplitudes of cyclic surface tensile stress and interface shear stress for the thicker coating, together with the interface shear stress shifting from a tensile-compressive alternating mode to a monotonous tensile one. The impact resistance of coated components under repetitive impacts is interpreted on thermodynamics where the thicker coatings mitigate impact mechanical energy dissipation of plastic strain energy in both coating and steel substrate, and accommodate larger reversible elastic strain energy during the periodic loading-unloading of impact cycles. [ABSTRACT FROM AUTHOR]