Influence of GNS on microstructure and wear resistance of high-boron-iron-based hardfacing alloy

This study describes the development of a novel slag-free self-shielded metal-cored wire. Various concentrations (0 wt.%, 0.15 wt.%, and 0.3 wt.%) of graphene nanosheets (GNS) were included in the welding wire. In this study, a range of iron alloys, including boron and varying amounts of GNS, were synthesized by applying them to Q235 steel plates. The microstructure, microhardness, and wear resistance of the hardfacing alloy were then systematically investigated. The findings of the study indicate that the Fe ₂ B phase is mostly seen at the interfaces between grains. When GNS are added to the hardfacing alloy, the morphology of the Fe ₂ B phase changes. The structure changes from mainly fishbone-shaped to rod-shaped and granular forms. The Fe ₂ B intergranular phase exhibits a progressive rise in percentage, with respective values of 40.3%, 41.9%, and 43.1% seen when GNS are not added, when 0.15 wt.% GNS is added, and when 0.30 wt.% GNS are introduced. The incorporation of GNS results in a consistent and progressive enhancement in the average microhardness. The hardness value was determined to be 454 HV in the absence of GNS, 513 HV with the addition of 0.15 wt.% GNS, and 520 HV with the addition of 0.30 wt.% GNS. The incorporation of GNS into the hardfacing alloy results in an enhancement of the matrix strength and a modification of the Fe ₂ B phase, hence improving the wear resistance. The wear rate and friction coefficient demonstrate a declining pattern, with micro-cutting and fatigue wear identified as the primary wear processes.