Application of Plasma Arc Injection Surface Alloying to Automobile Camshafts

By adding alloying elements to the surface layer of the cam face of cast iron camshafts during melting and rapid cooling by plasma arc a chilled structure with high wear resistance has been successfully obtained. An injection system, introducing carbide powder into the plasma jet, was used to supply alloying elements to the molten matrix. The alloyed layer obtained, with a maximum thickness of 2 mm and an alloying element concentration of 200∼, had a homogeneous structure with very high hardness. Selection of a suitable concentration of alloying elements reduced the wear rate to 20% of normal levels in engine tests.