Medium-carbon low-cost L245-L320-grade pipeline steel and manufacturing method thereof

The invention relates to medium-carbon low-cost L245-L320-grade pipeline steel and a manufacturing method thereof. The pipeline steel comprises the following chemical components by mass percent: 0.14 to 0.18% of C, 0.1 to 0.3% of Si, 0.5 to 0.7% of Mn, 0.005% or less of S, 0.015% or less of P and 0.02 to 0.06% of Al, and the balance being iron and unavoidable impurities. The technological process comprises the steps of KR, converter smelting, deoxidation alloying, CAS, LF, VD/RH, continuous casting, 48 hours of casting blank stacking and cooling, casting blank heating, scale removal, rough rolling, finish rolling, ACC, straightening, cooling, flaw detection, and marking and storage. According to the medium-carbon low-cost L245-L320-grade pipeline steel and the manufacturing method thereof, the content of carbon elements is increased, the utilization amounts of V, Ti and Nb are decreased, the alloy cost is effectively reduced, the fineness degree and uniformity of the structure of a product are improved, and t