Microstructure and abrasive wear properties of M(Cr,Fe)7C3carbides reinforced high-chromium carbon coating produced by gas tungsten arc welding (GTAW) process

In the present study, high-chromium ferrochromium carbon hypereutectic alloy powder was coated on AISI 4340 steel by the gas tungsten arc welding (GTAW) process. The coating layers were analyzed by optical microscopy, X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray energy-dispersive spectroscopy (EDS). Depending on the gas tungsten arc welding pa-rameters, either hypoeutectic or hypereutectic microstructures were produced. Wear tests of the coatings were carried out on a pin-on-disc apparatus as function of contact load. Wear rates of the all coating layers were decreased as a function of the loading. The improvement of abrasive wear resistance of the coating layer could be attributed to the high hardness of the hypereutectic M7C3 carbides in the microstruc-ture. As a result, the microstructure of surface layers, hardness and abrasive wear behaviours showed different characteristics due to the gas tungsten arc welding parameters.