Wear and Fatigue of Plasma Carburized Vanadium Carbide Stainless Cast Irons

Evaluation of vanadium carbide stainless cast iron (vanadium carbide cast iron), treated by plasma carburizing, was performed through the examination of wear and rotation bending fatigue. Difference in the form of the primary vanadium carbide (VC) in the matrix affected the wear and rotation bending fatigue properties. The as-cast spheroidal vanadium carbide cast iron has high wear resistance and low rotation bending fatigue resistance in comparison of the as-cast dendritic VC cast iron. The 3-10 μm deep layers that were formed by plasma carburizing at various treatment times and temperatures on the vanadium carbide cast irons containing spheroidal or dendritic VC were composed of iron, chromium and vanadium carbides, and were responsible for hardening the vanadium carbide cast iron. The difference between the wear resistance of as-cast spheroidal VC cast iron and that of as-cast dendritic VC cast iron remained unaltered by plasma carburizing, and wear resistance of the plasma carburized materials increased compared with the untreated material . Plasma carburizing leads to the decrease of the rotation bending fatigue resistance of vanadium carbide cast irons, regardless of the difference in the form of the primary vanadium carbide. Fatigue crack initiated near the boundary between the plasma carburized case and core material.