Microstructure and wear behavior of spray-formed and conventionally cast rolls of 18Cr–2.5Mo–Fe alloy

Relationships among the carbide morphology, microstructures and the wear behavior of sand-cast and spray-formed high Cr white cast irons were studied. The eutectic carbides in the spray-formed material are of small blocky shaped, uniformly distributed M3C and M7C3, while in the sand-cast materials, they are non-uniformly distributed, large needle shaped M3C. Hardness is nearly the same for the as-spray-formed and as-sand-cast materials. After the heat treatment, the sand-cast material had a large increase in hardness, while the spray-formed material had only a slight increase, and the former shows a much higher hardness than the latter, primarily due to higher C and Mo contents of the former. The spray-formed material showed a better fracture-resistance than the sand-cast material. The wear mechanisms were mainly adhesive wear for both soft and hard counterparts for the spray-formed materials, and switched from mainly adhesive wear for the soft counterpart to mainly abrasive wear for the hard counterpart for the sand-cast materials.