The invention relates to a pipeline steel for
deep sea and a production method thereof. The pipeline steel for
deep sea comprises the following components in percentage by weight: 0.025-0.080% of C, 0.05-0.50% of Si, 1.20-1.60% of Mn, less than or equal to 0.015% of P, less than or equal to 0.003% of S, 0.05-0.30% of Mo, 0.03-0.06% of Nb, 0.005-0.025% of Ti, 0.01-0.04% of Al, less than or equal to 0.010% of N and 0.0010-0.0050% of Ca used as main components, and less than or equal to 0.03% of As, less than or equal to 0.01% of Sb, less than or equal to 0.02% of Sn, less than or equal to 0.01%of Pb, less than or equal to 0.01% of Bi and less than or equal to 0.0005% of B used as residual elements. The production method comprises the following production steps:
smelting according to clean steel, and carrying out
continuous casting to obtain a blank; heating the cast blank; carrying out rough rolling; carrying out fine rolling; relaxing; cooling; relaxing again; straightening; and carrying out
air cooling to
room temperature. The pipeline steel has simple ingredient and technology, the thickness of the pipeline steel is more than or equal to 25mm, and the pipeline steel is used for
deep sea pipelines. The Rt05 of the pipeline steel is more than or equal to 450MPa, Rm is more than or equal to 550MPa, Rt05 / Rm is less than or equal to 0.85, A50mm is more than or equal to 40%, Agt is more than or equal to 10%, -40DEG C KV2 is more than or equal to 200J, and -20DEG C DWTT (Drop-Weight Tear Test) SA is more than or equal to 85%.