Effect of powder addition ratio on the microstructure and abrasive wear resistance of hardfacing alloys deposited by composite powder particles and solid wire

Composite powder particles with the size of 10-30 mesh were prepared by a series of processes including dry mixing, wet mixing with the addition of binding admixture, rotary pelleting, sintering and screen sizing on powder components. Those composite particles presetting on base metals were used as welding consumable together with solid wire which can be considered as arc carrier. High chromium alloys were deposited by the method of self-shielded open arc welding. The effects of powder addition ratio on the microstructure and abrasion resistance were investigated by optical microscopy (OM), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicate that, with powder addition ratio increases from 30% to 45%, the microstructure changes from the hypoeutectic to the hypereutectic. The dominant matrix converts changes from γ-Fe to α-Fe and the morphology of M₇C₃-type carbides transits from inter-granular reticular or dendritic shapes to granular or block-like ones. The results of wear test show that their abrasion resistance is excellent and corresponds to the one of flux-cored wire hardfacing alloys with such processing merits as simple and economic. The wear mechanism mode of hardfacing alloys includes micro-cutting and micro-spalling.