Boriding Treatment of Low Alloy Steels: Effect of Holding Time and Temperature

Boriding is a thermochemical treatment that can be applied to improve the mechanical and chemical properties of steels by surface modification while stilling adequate substrate properties. This kind of treatment is widely used to protect the degradation of the mechanical parts’ surface against wear. The boride atoms introduced into the steel can produce a hard metallic compound formed by diffusion and precipitation. The present study has been conducted in order to obtain an iron borides layer on two types of steel substrates 16NC6 and 20MC5 by using a powder consisting of B4C, NaBF4 and, SiC. The solid boriding treatment was carried out in an electric furnace heated to 950°C for three holding times of 2h, 4h and, 6h. The present research work focuses an the effect studying of holding time as a parameter on the thickness, structure, morphology, and hardness of layers obtained on low carbon steels by the case boriding. As confirmed by structure and microstructure characterization, the hard boride layers produced form two phases of FeB and Fe2B.