Mixing of chromium/carbon steel by compressive plasma flows

The microstructure, phase and element composition as well as mechanical properties of plasma mixed chromium/carbon steel have been investigated. Surface alloying of carbon steel with chromium has been performed with the use of the compressive plasma flow (CPF). In this technique, the action of relatively short, intense (∼100 μs and 13-18 J/cm2) plasma pulses leads to a melting of the near-surface layer (∼15 μm) of the steel substrate together with the Cr film (∼2.5 μm) predeposited on it. A rapid liquid-phase mixing in the molten state occurs, leading to the formation of new phases during fast resolidification. It is observed that plasma treatment of the system results in the formation of doped austenite stabilized by chromium. There is an increase in the austenite content with the growth of both the energy density and the number of pulses. Moreover, a change of the preferred orientation of austenite, from (1 1 1) to (2 0 0), occurs with the increase of the number of pulses. Phase and structural changes result in improvement of mechanical properties.