Phi350mm 34CrMo circular tube steel blank and smelting method thereof

The invention discloses a 350mm-diameter 34CrMo circular tube steel blank and a smelting method thereof, belonging to the technical field of steel tube smelting and rolling. The invention provides a 350mm-diameter 34CrMo circular tube steel blank with reasonable alloy component content and lower central segregation in the interior crystal phase structure, and a smelting method thereof. The 34CrMo circular tube steel blank comprises C, Si, Mn, P, S, Cr, Mo, Cu and Ni. The 34CrMo circular tube steel blank also comprises the following residual elements: Nb, Ti, B, V+Nb+Ti+B+Zr, As, Sn, As+Sn+Pb+Sb+Bi and Fe. The low-power central segregation rate of the finished product 34CrMo circular tube steel blank is Grade 0-0.25, and the spectrum direct-reading segregation degree is 1.03-1.05. The smelting method comprises the following steps: converter smelting, LF (ladle furnace) refining, RH refining, and continuous casting of the 34CrMo circular tube steel blank with the phi350mm cross section.