Detonation Spraying Cr₃C₂-NiCr Coatings and Its Effect on Fatigue Property of 2Cr10MoVNbN Steel Substrate

Cr3C2-NiCr coating was deposited on 2Cr10MoVNbN steel substrate by detonation spraying method.The defect,micro-hardness,fracture toughness,adhesion to the substrate and residual stress for as-sprayed coating were respectively investigated by means of optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffraction (XRD),energy dispersive spectrometer(EDS),micro-hardness tester,electronic tensile testing machine and X-ray strain apparatus.The effect of Cr3C2-NiCr coating on fatigue property of 2Cr10MoVNbN steel was studied.The results show that the porosity of the coating was 0.5%,the surficial hardness was 921 HV,the fracture toughness was 3.67 MPa·m1/2,and the adhesion to substrate was 63 MPa.Both surface and coating-substrate interface showed compressive residual stress.The Cr3C2-NiCr coating led to a significant decrease of fatigue property of the 2Cr10MoVNbN steel substrate.When the stress amplitude was less than 500 MPa,the reduction of fatigue life was more than 75% and the fatigue strength decreased about 134.7 MPa.Fatigue origins of the as-sprayed sample with the presence of Al2O3 particles were at the coating-substrate interface.