Surface modification of ferrous alloys with boron

This paper presents the effects of boronizing on ferrous alloys such as plain-carbon steel AISI 1018, high-strength alloy steel AISI 4340, and austenitic stainless steel AISI 304. The coatings were produced by thermochemical treatment with powder mixtures at temperatures of 850°C for 4 h. The microstructure of obtained coatings was investigated, the microhardness was measured, and the corrosion resistance and oxidation resistance were tested. By metallographic analyses, the thickness of the coatings was measured. Microhardness of the boron coatings was measured using loads of 10 gf, 25 gf, and 50 gf. Corrosion tests were performed in 5% HCl, 10% HCl, and 15% HCl at room temperature. To determine the oxidation resistance of the coatings, the isothermal method was used to observe the weight change at a temperature of 600°C for 12 h. Results indicated that the presence of boronized coatings on ferrous alloys greatly improved their microhardness, oxidation resistance, and corrosion resistance.