The invention relates to a production method of pipeline steel, which adopts the process
route of:
smelting in a
rotating furnace,
ladle furnace (LF) refining, vacuum degassing (VD),
continuous casting, heating by a
heating furnace, rough rolling, finish rolling, Mulpic cold control and finished product warehousing. The pipeline steel comprises the following alloying elements by
mass percent: 0.03-0.06% of C, 0.20-0.35% of Si, 1.60-1.70% of Mn, less than or equal to 0.015% of P, less than or equal to 0.005% of S, 0.04-0.06% of Nb, 0.008-0.02% of Ti, 0.15-0.25% of Ni, 0.20-0.35% of Cr, 0.10-0.15% of Mo, less than or equal to 0.0003% of H, less than or equal to 0.005% of N, less than or equal to 0.0015% of O and the balance of Fe; and the technical method combining rough rolling, finish rolling and Mulpic cold control are carried out under the following conditions: the
heating temperature of a billet is 1180-1230 DEG C, the first-stage blooming temperature is 1180-1220 DEG C, the accumulated deformation is more than or equal to 60% and the finish rolling temperature is 980-1060 DEG C; the second-stage blooming temperature of the billet is 880-900 DEG C, the finish rolling temperature is 780-810 DEG C and the accumulated deformation is more than or equal to 70%;
air cooling relaxation is carried out on a rolled steel plate till the temperature is 650-680 DEG C, 40-60% of polygonal ferrite (PF) is separated out before the steel plate is cooled; and then, the steel plate is rapidly cooled by Mulpic, wherein the
cooling speed is 30-35 DEG C / min, and the finish
cooling temperature is 300-360 DEG C. The pipeline steel produced by the method is better in low strain
ageing sensitivity and deformation resistance.