Effects of load on loosing abrasive wear behavior of Fe-Cr-C-Nb hardfacing alloys

Fe-Cr-C-Nb hardfacing alloys were prepared by gas metal arc welding (GMAW) method. Loosing abrasive wear tests of dry sand/rubber wheel were carried out on Fe-Cr-C-Nb alloys at different normal loads (70~190 N). Microstructures and wear scar characteristics of alloy were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), weight loss test, stereo microscopy, laser scanning confocal microscopy (LSCM), and Vickers-hardness test to investigate the abrasive wear behavior of alloy in various normal loads. The results show that, the microstructures of Fe-Cr-C-Nb hardfacing alloys are mainly composed of primary austenite matrix, reticular eutectic structure, and NbC hard phase distributed on the matrix. The wear loss and wear scar depth increase with the increase of normal load. The wear mechanism is mainly composed of the micro-cutting of austenite matrix and the brittle flaking of NbC and M₇C₃. The increase of normal load aggravates the machining hardening of wear scar subsurface, thus improving the wear resistance of austenite matrix and leading to the slow increase of wear loss and wear scar depth.