Applying Thermo-Reactive Diffusion Method to Surface Coating of H13 Tool Steel Using Ferrovanadium, Ferrochromium, and Misch Metal

Abstract

The thermo-reactive diffusion (TRD) process is a method for surface hardening that improves the hardness, corrosion resistance, and wear resistance of the materials. In this study, the effect of composition was investigated, by using 8, 12, 16, 20, and 24 wt% of ferrochrome and ferrovanadium with equal amounts, along with 3 wt% aluminum and borax. The TRD process was carried out at 1000°C for 7 hours on AISI H13 hot work tool steel so that a complex coating of chromium-vanadium carbide was formed on the H13 substrate. Optical and scanning electron microscopes were used to evaluate the thickness and microstructure of the samples, respectively. Moreover, the amount of alloying elements and constituent phases on the surface were analyzed by point analysis and X-ray diffraction. The micro-hardness method was used to evaluate the hardness of the samples. The results of this study showed that by increasing the amount of ferroalloy, the hardness and thickness of the coating increase. The optimal composition with 8% ferrochrome and 8% ferrovanadium was found to yield a coating with a thickness of 7.65 μm and a hardness of 2115 HV.