Fe–15 wt-Cr–X wt-C hardfacing surface layer: Wear resistance and its enhanced mechanism with C additive

Abstract

An electrode with different C additives was developed. The microstructure of the hardfacing surface layer was observed by optical microscopy. The phase structure was determined by X-ray diffraction. The hardness and wear resistance of the hardfacing surface layer were measured respectively. The worn-out surface and three-dimensional morphology were observed by field emission scanning electron microscope equipped with energy dispersive X-ray spectrometry. The relation curve between mass fraction of M₇C₃ carbide and temperature was calculated according to thermodynamics software Thermo-Calc. The results show that, with the increase in C additive, the hardfacing surface layer changes from a hypoeutectic structure to a hypereutectic one. Meanwhile, the primary phase changes from austenite to carbide. The hardness and wear resistance of the hardfacing surface layer increase gradually with the increase in C additive, and when the C additive is 25 wt-, they are the largest. With the increase in C content, the precipitation temperature of M₇C₃ decreases from 1280 to 1260°C, while the maximum amount of M₇C₃ increases instead, which is from 0·154 to 0·313. The reason of the improvement for wear resistance of the hardfacing surface layer is that the carbide initiates and the amount of M₇C₃ increases.