600-MPa grade vanadium-containing high-strength hot-rolled steel bar and production method thereof

The invention relates to a 600-MPa grade vanadium-containing high-strength hot-rolled steel bar and a production method thereof, and belongs to the technical field of metallurgical steel-making and processing; the technical scheme is that the steel bar is prepared by the following components by mass: 0.21-0.25% of C, 0.35-0.60% of Si, 1.35-1.55% of Mn, 0.08-0.12% of V, 0.005-0.04% of N, not more than 0.040% of S, not more than 0.040% of P, and the balance of Fe and inevitable impurities; by adopting vanadium-increasing, nitrogen-increasing, and nitrogen-fixing processes during the smelting process, and by decreasing the initial rolling temperature and the finish rolling temperature during the rolling process, fine-grain, solid-solution and precipitation strengthening are realized at a lowtemperature and a high pressure, so the strength is increased; the hot-rolled steel bar contains a dual-phase structure of ferrite and pearlite, wherein the pearlite accounts for 25-50%; good cooperation of strength and toughness can be reached by controlling ratios, forms and sizes of the phases.