High-strength steel plate for acid-resistant line pipe, method for producing the same, and high-strength steel pipe using high-strength steel plate for acid-resistant line pipe
A high-strength steel plate and a technology for manufacturing method, which are applied in the field of high-strength steel plate for acid-resistant line pipe and high-strength steel pipe using the high-strength steel plate for acid-resistant line pipe, can solve cooling stop temperature deviation, cooling rate deviation, steel plate Material deviation and other problems, to achieve the effect of excellent hardness uniformity, HIC resistance and SSCC resistance
Active Publication Date: 2022-03-22
JFE STEEL CORP
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Problems solved by technology
[0006] On the other hand, when the thickness of the scale on the surface of the steel plate is uneven, the cooling rate of the steel plate below it also varies during cooling, and the local cooling stop temperature variation in the steel plate becomes a problem.
As a result, variations in the steel sheet quality in the sheet width direction occur due to variations in scale thickness
Method used
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Embodiment
[0119] Steels (steel grades A to I) having the composition shown in Table 1 were made into slabs by continuous casting, heated to the temperature shown in Table 2, and then rolled at the end temperature shown in Table 2 Steel sheets with the thicknesses shown in Table 2 were prepared by hot rolling at the rolling reduction ratio. Then, under the conditions shown in Table 2, the cooling control of the steel plates was performed using a water-cooling type cooling control device. Immediately thereafter, the steel sheet was reheated according to the method shown in "Heating method" in Table 2 so that the surface temperature of the steel sheet became the "Maximum temperature during reheating" in Table 2.
[0120] [organization specific]
[0121] The microstructure of the obtained steel plate was observed with an optical microscope and a scanning electron microscope. Table 2 shows the structure at a position 0.5 mm below the surface of the steel plate and the structure at the cent...
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Abstract
The present invention provides an acid-resistant high-strength steel sheet for line pipe, which is excellent in HIC resistance and SSCC resistance in a severe corrosive environment, and is also excellent in hardness uniformity in the thickness direction. The high-strength steel plate for acid-resistant line pipe of the present invention is characterized in that it has a predetermined composition, and the steel structure at 0.5 mm below the surface of the steel plate has a dislocation density of 0.5×10 14 ~7.0×10 14 (m ‑2 ) bainite structure, the difference ΔHV between the average value of Vickers hardness at 0.5 mm below the surface of the steel plate and the average value of Vickers hardness at the center of the steel plate thickness is 25 HV or less, and has a tensile strength of 520 MPa or more.
Description
technical field [0001] The present invention relates to an acid-resistant high-strength steel plate for line pipe, which is suitable for line pipe in the fields of construction, marine structures, shipbuilding, civil engineering, and construction industrial machinery, and has excellent material uniformity in the steel plate, and a manufacturing method thereof. In addition, the present invention relates to a high-strength steel pipe using the above-mentioned high-strength steel plate for acid-resistant linepipe. Background technique [0002] Generally, a line pipe is manufactured by forming a steel plate produced by a thick plate rolling mill or a hot rolling mill into a steel pipe by UOE forming, press bending, roll forming, or the like. [0003] Among them, line pipes used to transport crude oil and natural gas containing hydrogen sulfide require not only strength, toughness, weldability, etc., but also resistance to hydrogen-induced cracking (HIC (Hydrogen Induced Cracking...
Claims
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IPC IPC(8): C22C38/00C21D8/02C22C38/06C22C38/58
CPCC21D8/02C22C38/00C22C38/06C22C38/58C22C38/02C22C38/04C22C38/12C22C38/14C22C38/22C22C38/24C22C38/26C22C38/28C22C38/18C21D9/085C21D9/08C21D1/19C21D1/02C21D9/46C21D6/005C21D8/0231C21D8/0263
Inventor 太田周作横田智之长谷和邦田村雄太
Owner JFE STEEL CORP