Research on the Microstructural Regulation and Strengthening Mechanism of Silicon and Vanadium in High-Carbon Pearlitic Steel

The synergistic effects of Si and V on the microstructural evolution and mechanical hardness of high-carbon pearlitic steels were systematically evaluated using six industrially hot-rolled wire rods. The results show that Si provides solid solution strengthening and refines prior austenite grains and pearlite colonies through grain boundary segregation and elevated cementite nucleation barriers. However, its refinement of the pearlite interlamellar spacing is limited (6.5%). This refinement is primarily attributed to the interfacial solute drag effect from Si enrichment suppressing cementite growth kinetics. In contrast, V dictates the microstructural evolution through a “dual-scale” precipitation behavior. Integrating microstructural observations with thermodynamic calculations, it is inferred that coarse VC particles (50-150 nm) precipitate predominantly within the austenite phase region, effectively pinning advancing phase transformation interfaces and leading to a substantial interlamellar spacing refinement (47.5%). Concurrently, the diffuse nano-sized VC particles (4-8 nm) within the ferrite matrix contribute to substantial precipitation strengthening. Furthermore, the co-addition of Si and V markedly improves pearlite thermal stability, effectively inhibiting cementite spheroidization (with the rate dropping from 9.12% to 1.18%). A semi-quantitative evaluation based on physical models indicates that grain refinement and precipitation strengthening account for over 60% of the calculated strength increment, dominated by V-induced interlamellar spacing refinement and nano-precipitates. • Si and V effects are systematically evaluated in an industrial alloy framework. • V dominates interlamellar spacing refinement (47.5%); Si effect is minor (6.5%). • Phase-driven dual-scale VC precipitation governs microstructural evolution. • Si-V synergy inhibits cementite spheroidization, improving thermal stability. • Semi-quantitative evaluation of Si and V induced strengthening contributions.