Synthesis of tungsten carbide composite surface on steel substrates

Wear resistant, hard surfaces of tungsten-iron carbide on mould steel are synthesised by first carburizing the surface of the mild steel; spot welding tungsten wires to the carburized surface; directing an electron beam onto the tungsten so as to melt the tungsten and cause it to react and alloy with the carburized steel. The localized energy from a focused beam heated the material to temperatures exceeding vaporization temperatures of the steel which is sufficient to melt any high temperature carbide forming alloying element and synthesize carbides. Networks of M6C tungsten rich carbide at different compositions and cooling rates were synthesized by using a 60 kV electron beam welding unit. Concentration of tungsten was varied from less than 1 to 30 weight pct. by varying processing parameters. The chemistry and so the hardness of a synthesized surface was uniform along the depth the former was found to be within 1% variation and the latter could be raised to values as high as 1000 Hv. The alloyed layer and the interface is free of pores.