Hardening Due to Vanadium Carbides Formed During Short-Time Aging of Hadfield Steels

Abstract

Precipitation hardening is a promising approach for strengthening of Hadfield steels. The present study examines the potential to achieve this by combining vanadium addition (up to 2 wt pct) with short-time aging (15 minutes) at 1173 K (900 °C). It was found that such a treatment is sufficient to generate a dispersion of nanoscale precipitates that provided a significant increase in hardness. Small-angle neutron scattering and transmission electron microscopy measurements were performed to quantify the particle dispersion, and Orowan precipitate hardening predictions made using the parameters thus obtained show good correspondence with the observed rates of age hardening, suggesting the precipitates are resistant to shearing. The present steels containing vanadium showed a small reduction in work-hardening capacity and this is believed to be due to carbon depletion from the matrix. It is concluded that the addition of vanadium and a short aging treatment at 1173 K (900 °C) provide a promising pathway to imparting hardness increases that provide gouge resistance during the running-in period of components made from Hadfield steel. For optimum performance, additional carbon should be added to maintain the solute carbon content of the matrix, and hence the matrix work-hardening rate.