Improvement of mechanical and operational steel characteristics by strengthening the surface

Abstract

The growing demands in the mining industry require steel products capable of withstanding heavy loads. To achieve enhanced mechanical, service, and operational properties in steel, common methods include adjusting carbon content, optimizing primary element concentrations, and applying expensive microalloying and heat treatments. For metal products operating under high vibration or as contact pairs, surface layer strengthening is essential. This study investigates the relationship between the composition of the saturating medium, the degree of cold plastic deformation, and the effects of saturation regimes on the structure, mechanical, and service properties of low-carbon steel. Samples were analyzed after annealing and cold plastic deformation using metallographic analysis, mechanical and tribological testing, X-ray diffraction, and chemical and X-ray spectral analysis. The results indicate that cold plastic deformation enhances the diffusion mobility of boron and carbon. To produce effective boron-cemented surface layers, a saturating mixture with up to 4.5% boron carbide is recommended. These boron-cemented layers, containing phases such as Fe2B, Fe3(CB), and Fe23(CB)6, exhibit strong adhesion to the matrix and superior mechanical and tribological properties. The boron-bearing phases are partially located along grain boundaries and within grains. This method allows for boron-cemented layers up to 2.0 – 2.3 mm deep, nearly double the depth achieved by traditional cementation methods, offering significant potential for strengthening steel products in the mining industry.