Plasma-transferred arc-welded composite hardfacings with ZrB2 and TiC reinforcements

The traditional approach to prolonging the lifetime of wear parts is to use wear-resistant materials. One such material is hardfacing, which, in addition to its primary function, contributes to sustainability objectives by preventing the failure of wear parts and allowing them to be used more efficiently. The present study focuses on hardfacings that are free of critical raw materials (CRM) and are based on materials that are non-harmful to health and the environment, in line with the European Union policy on material supply chains, availability, and safety (REACH legislation). The present study used plasma-transferred arc welding (PTAW) to produce a 316L stainless steel-based hardfacing reinforced with non-CRM components ZrB2 and TiC. Pre-applied mixtures of matrix powders and ceramic components on a soft S235 steel substrate were remelted using optimized PTAW parameters, specifically with a welding current of 115 A and 135 A and a linear torch velocity of 0.7 mm/s. Microstructure analysis and phase identification were conducted using the scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods on pre-prepared cross-sections. The Vickers hardness (HV) was measured under different indenter loads. Due to the interaction between the iron-based alloy and ceramic components under PTAW, carbide-boride phases with a complex composition were formed, contributing to the increased hardness of the material. The highest hardness value (HV5) was observed in the hardfacing with the composition of (ZrB2 + TiC) + 60 vol% 316L stainless steel, processed with a welding current of 135 A. These results demonstrate the potential for applying ceramic-reinforced stainless steel hardfacing in industrial applications.