Effect of bulk heat treatment and plasma surface hardening on the microstructure and erosion wear resistance of complex-alloyed cast irons with spheroidal vanadium carbides

Abstract

The results of an investigation of the effect of bulk quenching from temperature in the range of 760–1050°C, cryogenic treatment (–196°C) and surface plasma hardening on the abrasive-erosion wear of frugally alloyed V–Cr–Mn–Ni cast irons with spheroidal vanadium carbides have been presented in this article. It has been found that cast irons containing 5.0–7.5% V, 4.5–9.0% Cr, and 5.5–5.7% (total) of Mn and Ni after heat treatment have a 2–3-fold advantage in wear resistance compared to the prototype high-vanadium cast iron (11.9% V, 12.9% Mn). The maximum wear resistance of cast irons studied is achieved by quenching at 760°C followed by plasma surface hardening, as well as quenching at 840°C, followed by cryogenic treatment. These treatments result in the formation of an optimum microstructure that consists of spheroidal vanadium carbides, eutectic carbides M₇C₃, and a martensite-austenite matrix reinforced by secondary carbides. The increase in quenching temperature leads to an increase in the amount of residual austenite and decrease in the erosive wear resistance of cast irons.