Surface hardening of laser melting deposited 12CrNi2 alloy steel by enhanced plasma carburizing via hollow cathode discharge

Abstract Plasma carburizing of 12CrNi2 alloy steel fabricated by laser melting deposition was carried out in a propane-containing atmosphere at temperature of 930 °C with and without hollow cathode discharge (HCD). The generation of the HCD in the carburizing process was achieved by adding an auxiliary cathode opposite the alloy steel sample. The carburized samples were characterized by analysis of microstructure, microhardness and wear performance. The assistance of HCD increased the carbon concentration in the carburized layer and the case depth without changing the carburizing atmosphere and discharge voltage, indicating the improvement of carburizing kinetics. This leads to an increased volume fraction of acicular martensite and an increased the microhardness of the carburized layer as well as the improvement of the wear resistance of alloy steel.