X70 pipeline steel hot rolled coil and manufacture method thereof

Abstract

The invention relates to an X70 pipeline steel hot rolled coil and a manufacture method thereof. The coil comprises the following ingredients in percentage by weight: 0.02 to 0.05 percent of C, 0.10 to 0.30 percent of Si, 1.00 to 1.40 percent of Mn, at most 0.015 percent of P, at most 0.002 percent of S, 0.015 to 0.05 percent of Alt, 0.05 to 0.08 percent of Nb, 0.02 to 0.035 percent of V, 0.01 to 0.02 percent of Ti, 0.10 to 0.50 percent of Cr, at most 0.006 percent of Ca, 0.10 to 0.30 percent of Ni and 0.10 to 0.30 percent of Cu. The manufacture method is mainly characterized in that a, the laser fused (LF) refining is carried out outside a furnace: desulfurization is carried out until the weight percent of S is less than or equal to 0.0015 percent; b, the RH refining is carried out outside the furnace: Ca-Si lines are added before the vacuum smelting and steel outlet; c, the continuous casting temperature is 1553+ / -15DEG C; d, the continuous casting pulling speed is higher than or equal to 1.0 m / min; e, the plate blank heating temperature is lower than or equal to 1200 DEG C; f, the rough rolling terminating temperature is 930 to 1030 DEG C; g, the finish rolling terminating temperature is 780 to 850 DEG C; h, the steel band coiling temperature is 450 to 580 DEG C; and l, the cooling speed of the layer flow cooling is higher than or equal to 5 DEG C / s. The X70 pipeline steel hot rolled coil simultaneously meets the requirements of high toughness and hydrogen sulphide corrosion resistance of X70 pipeline steel.

Description

technical field [0001] The invention relates to a hot-rolled coil of X70 pipeline steel and a manufacturing method thereof. technical background [0002] Pipeline transportation is the most economical, safe and efficient means of transporting oil and natural gas over long distances. With the increasing amount of oil and natural gas extraction, the transportation medium of the pipeline contains H 2 As S increases, hydrogen sulfide corrosion (HIC and SSCC) becomes one of the important forms of pipeline steel corrosion, which not only affects the service life of pipeline steel, but also causes significant economic losses, environmental pollution and casualties. [0003] Anti-H 2 In addition to the high strength, high toughness and weldability required by conventional pipeline steel, S-corrosion pipeline steel must also meet the detection requirements of HIC resistance and SSCC resistance. From the current research, it is difficult to ensure high strength and good corrosion r...

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Problems solved by technology

[0005] Except for patent 3, the hydrogen sulfide corrosion-resistant pipeline steels disclosed in the above patent documents are all X65 and below grade pipeline steels. Although the actual strength of patent 3 meets the requirements of X70 grade pipeline steel, it cannot simultaneously have HIC resistance and Anti-SSCC performance

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