Study of pulsed high-energy density plasma modified 0.45%C steel

The hardness of the surface of 0.45%C steel is improved by about six times after the surface is modified by pulsed high-energy density plasma (PHEDP) composed of particles of titanium and nitrogen. A layer of thin film about 1 μm thick is formed on the treated surface and the microstructure of the film is examined by transmission electron microscopy, which shows that the film comprises TiN, Ti2N(α), Ti2N(β) and FeTi phases. In PHEDP surface modification, the process of ion implant combined with melting and rapid quenching contributes to the formation of the polyphase film on the surface of 0.45%C steel, especially to the formation of nanometer particles and the metastable phase of Ti2N(α) in the film. The structure polyphase film is the main reason for the hardness improvement of the surface of 0.45%C steel. The characteristics of Ti2N(α) and Ti2N(β) phases are discussed in paper.