Surface Treatment of 45 Steels by Plasma Beam Alloying and Plasma Surface Quenching

Abstract

Plasma beam is currently advisable and advantageous in surface modification for several reasons; for instants, high energy, portability and low cost. In this study, plasma beam was employed to deposit pre-paste, and also used for surface quenching. The results are shown that a uniformed harden layer free of crack and porosities with a thickness of 1.8-2.2mm can be produced by both two methods. After plasma beam alloying, the overlayer with obvious two interfaces can achieve a maximum hardness of 1100HV0.2. This improvement is the mainly contribution not only by land-like TiC reinforced particles and Fe2.5Ti0.5O4, a product of reaction between the pre-paste and molten matrix, with dispersive distribution at the surface, but also alloying elements enriched at the top of molten pool. The experiment suggested that the hardness of the surface was also highly affected by the parameters of plasma beam process alloying; namely, the higher velocity plasma beam moves and the more TiC particles contained, the higher hardness can be obtained. In contrast with the former process, after plasma surface quenching, the overlayer with one interface has a maximum hardness of 600HV0.2.