Microstructure and abrasive wear resistance in the miller test of a martensitic Fe-C alloy with V and W carbides

A very popular material used for parts and components of machines operating under abrasive wear is cast alloyed steel with medium and high carbon content, which ensures sufficient hardness, and with the addition of elements such as Cr, Mn, Si, Ni, Mo. To improve the abrasive wear resistance of the tested alloys, carbide-forming elements such as vanadium were introduced in the amount of about 18 wt.% during melting. One melt, in which the total carbon content ranged from 3.4 to 3.9 wt.%, additionally contained 4.5 wt.% W. The measured hardness of the tested samples in the alloy with a carbon content of 3.4 wt% and the addition of 17.7 wt% V and 4.5 wt% W, the as-cast was approximately 535 HV and increased to approximately 665 HV after quenching. The highest hardness was obtained for an alloy containing 3.9 wt% C and 17.9 wt% V. In the as-cast state, the hardness of this alloy was 850 HV and increased to 950 HV after quenching from a temperature of 880°C and cooling in a 15% of Polihartenol HI polymer solution. The microstructure of test castings was composed of a martensitic matrix with low amounts of retained austenite characterized by the presence of lamellar carbides with a spherical cross-section, evenly distributed in the alloy matrix. In the majority of cases, those were M2C carbides, though in alloys with vanadium and tungsten, complex carbides of the (V,W)xCy type were also observed to occur. The highest resistance to abrasive wear of approximately 950 HV was obtained in a martensitic alloy with 17.9 wt% V+0.1 wt% W, quenched from a temperature of 880°C and cooled in a 15% of Polihartenol HI polymer solution. Its weight loss was two times lower than the weight loss of the reference cast GX70CrMnSiNiMo2 steel.