Precipitation of Vanadium Carbides for Improved Resistance to Gouging during the Running-In of Hadfield Steels

Abstract

Precipitation hardening is a promising approach for strengthening of Hadfield steels to provide resistance to wear loss due to gouging in the initial ‘running-in’ period of mining components. The present study examines the potential to achieve this by combining vanadium addition (up to 2 wt.%) with short time aging (15 min) at 900 °C. It was found that such a treatment is sufficient to generate a dispersion of nano-scale precipitates that provided an increase in hardness and up to a factor three increase in gouging resistance in the as-processed state. 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 showed a small reduction in work hardening capacity and resistance to gouging in the work hardened state, after vanadium addition and aging. 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 900 °C provides a promising pathway to imparting 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.