Fe-Based Coatings on Gun Steel Surface Deposited by PTA and Their Erosion Behavior

Fe-based erosion resistant coatings A and B were prepared by plasma surfacing on the surface of gun steel.The microstructure and elements of the coatings were analyzed by X-ray diffraction,scanning electron microscopy and energy dispersive spectrometer.The hardness of the coating was measured by Vickers hardness tester,and the erosion resistance of the coating was tested by high speed heat flow generating device.The results show that both Fe-based coatings have good metallurgical bonding with the substrate.Coating A is com posed of Fe3Ni2,(Cr,Fe)7C3 and Fe-Cr solid solution.Coating B is composed of Cr3Ni2,Fe0.64Ni0.36,Fe7C3,Fe-Cr solid solution.After 40 tests of high-speed heat flow's erosion,the erosion behavior of the coatings was observed under scanning electron microscopy.Results show that,the erosion process of Coating A is extended from "intergranular erosion",to "crystallization erosion",then to "full crystal erosion".Coating B shows no obvious erosion behavior under scanning electron microscopy,but has produced transcrystalline cracks in the hot and cold cycle process.The two coatings have significantly enhanced the erosion resistance compared with the gun steel.