Mechanism of Electroshock Treatment on Hardness and Wear Resistance of Tempered 8Cr4Mo4V

Abstract

In order to further improve the wear resistance of tempered 8Cr4Mo4V steel, an electroshock treatment (EST) was conducted on the material. By means of Vickers hardness and friction-wear tests, the influence of different EST parameters on the wear resistance of materials was analyzed. The result proves that a slight decrease in the Vickers hardness of the sample is caused by EST, but the hardness consistency significantly is improved (44.7%) under appropriate treatment parameter (EST2). Meanwhile, the wear rates of specimens decrease by 42.9%, 50.0% and 71.4% under treatment of EST1-EST3, respectively. The EBSD and XRD indicates that the changes in hardness and wear resistances of 8Cr4Mo4V originates from the comprehensive effect of dislocations and carbides under the regulation of EST. In EST1, the precipitation and aggregation of carbides promotes secondary hardening, thereby reducing the wear rate. Opposite phenomenon occurs in EST2, carbide precipitation is suppressed while the lattice distortion is aggravated, the hardness rebounds slightly compared to EST1. In EST3, the greater decrease in hardness results in the formation of oxide film on the surface, further reducing the friction coefficient and wear rate.