Improvement on the wear-resisting property of tool steel by CDC treatment

Typical die steels, H13 and Cr12MoV were treated by CDC, the microstructure and carbide constituents in carburized layer were studied by means of optical microscopy, SEM and X-ray diffractometer. It was found that the optimal carbon potential was 1.2% when the steel in Fe-Cr-C ternary system was treated by CDC at 950℃. The superficial microstructure in the H13 steel treated by CDC consisted of martensite and dispersed carbide. The carbide was mainly Cr_7C_3 whose size was 200～300nm. The penetration hardness value of H13 steel treated by CDC increased by Hm500 compared to that of the unsettled at the same conditions. The effective induration depth reached 550μm. The bearing resistance of H13 steel treated by CDC was obviously superior to that of extrusion mould by the nitrification treatment. When Cr12MoV steel was treated by CDC, the number of carbide in the surface obviously increased. The surface hardness value was increased by Hm400, and the depth of the hardness layer was 1000μm. It has been proved in practice that the life-span of Cr12MoV steel treated by CDC was improved twice than that of Cr12MoV steel treated by conventional quenching and then tempering.