Application of Low-Temperature Atmospheric-Pressure Plasma in Metallurgy

Technologies for plasma heating of steel in a continuous caster tundish, plasma-arc remelting nitriding, and metal surface modification are developed using an efficient dc low-temperature plasma generator with a self-adjusting arc length, vortex stabilization, and an expanding gas-discharge channel. The temperature stabilization of the cast steel increases the fracture toughness and the critical crack opening in the deformed steel in both the transverse and longitudinal rolling directions. Remelting of steel in nitrogen plasma refines grains; increases the strength, ductility, total fracture work, and wear resistance under dry friction conditions; and decreases the corrosion rate. Plasma treatment saturates the metal surface with nitrogen and forms a wide range of structures with a deep and gradual transition zone, which ensures strong adhesion of the hardened layer to the base metal.