35CrMoV round steel (GB/T 3077) has a composition of 0.32–0.40% carbon (C), 0.17–0.37% silicon (Si), 0.40–0.70% manganese (Mn), 1.00–1.30% chromium (Cr), 0.20–0.30% molybdenum (Mo), 0.10–0.20% vanadium (V), ≤0.035% phosphorus (P), ≤0.035% sulfur (S).
Vanadium (V) and molybdenum (Mo) work synergistically to boost high-temperature stability via carbide interactions: Molybdenum forms stable molybdenum carbides (Mo₂C) that resist coarsening at elevated temperatures (up to 550°C)-coarsened carbides lose their ability to strengthen the steel. Vanadium complements this by forming ultra-fine vanadium carbides (VC) that pin grain boundaries, preventing grain growth (a major cause of strength loss at high temperatures). Additionally, VC acts as a "nucleation site" for Mo₂C, ensuring molybdenum carbides remain dispersed uniformly instead of clustering. Chromium (1.00–1.30%) forms Cr₂₃C₆ carbides that further reinforce the matrix, while carbon (0.32–0.40%) provides sufficient carbide-forming material without excessive brittleness. This trio of carbides (VC, Mo₂C, Cr₂₃C₆) ensures the steel retains its chemical structure and strength at temperatures where lower-alloy steels degrade.