Study of submerged and plasma arc welded composite hardfacings with a novel Cr 3

This paper studies possible uses of Cr3C2–Ni cermet prepared via mechanically activated synthesis as reinforcement in submerged arc welded (SAW) and plasma transferred arc welded (PTAW) Fe- and Ni-based hardfacings. The microstructure and phase composition of the hardfacings were analysed by scanning electron microscopy and X-ray diffraction, respectively. Vickershardness (HV30) was measured and two-body (ASTM G132) and three-body (ASTM G65) abrasive wear were tested. Cermet particles were found to be entirely dissolved in the SAW hardfacings, while in the PTAW hardfacings they were partially retained. The main phases in the Fe-based hardfacings were γ-Fe and α-Fe along with Cr7C3 in the PTAW hardfacing. The Ni-based SAW and PTAW hardfacings were mostly comprised of different carbides (Cr3C2, CrC, NiC0.22). Addition of cermet particles increased the hardness of the hardfacings 1.1–3.3 times, the effect being more pronounced in the Fe-based hardfacings and PTAW hardfacings. Under two-body abrasive wear conditions, composite hardfacings exhibited 1.2–7.8 times lower wear and under three-body abrasive wear conditions 1.4–9.4 times lower wear than the unreinforced hardfacings. The wear resistance of the PTAW hardfacings was improved considerably, while the effect of the matrix alloy was insignificant. Microcutting was the major wear mechanism under both two-body and three-body abrasive wear conditions, accompanied by microploughing in the SAW hardfacings in the former case and by the pull-out of carbide particles in the PTAW hardfacings in the latter case. The principle of the wear mechanism remained unaltered in the presence of cermet particles, but the wear was less severe