Study on the effect of saturating medium composition on the properties of steels during diffusion borosiliconizing

EDN: https://elibrary.ru/MXZJRA

Abstract

This study investigates the effect of ferrosilicon (FeSi) concentration (10%, 15%, 20%, and 25%) on the microstructure and properties of borosiliconized layers formed on GB 12Mn, AISI H13, and GB S50C steels. The pack boriding process was conducted at 950°C for 4 hours. The corrosion resistance, high-temperature oxidation resistance, and microhardness of the treated samples were systematically evaluated through immersion tests in 10% H₂SO₄ solution for 96 h, oxidation tests at 800 °C for 8 h, and microhardness measurements. The results show that as the FeSi concentration increases from 10% to 25%, the mass loss due to corrosion increases significantly for all three steels. GB 12Mn exhibits the best corrosion resistance (mass loss of 0.87%–1.41%), followed by GB S50C, while AISI H13 shows the highest mass loss (14.63%–42.87%). In high-temperature oxidation tests, all samples exhibit mass loss rates below 0.04%, indicating that borosiliconizing effectively enhances the oxidation resistance of the steels. Microhardness analysis reveals that FeSi concentration significantly affects the hardness characteristics: GB 12Mn achieves the highest surface hardness (1427 HV) and deepest hardened layer (approx. 130μm) at 10% FeSi; GB S50C exhibits optimal comprehensive performance at 15% FeSi, with a surface hardness of 1641 HV and a layer depth of approximately 150μm; AISI H13 shows a continuous increase in surface hardness with increasing FeSi concentration, reaching 1455 HV at 25% FeSi, but the hardened layer is relatively thin and exhibits non-uniform hardness distribution. Considering corrosion resistance, oxidation resistance, and hardness properties, 10% FeSi is recommended for GB 12Mn, 15% FeSi for GB S50C, and higher FeSi concentrations for AISI H13 depending on specific application requirements.