High-strength steel sheet for acid-resistant line pipe, method for producing same, and high-strength steel pipe using high-strength steel sheet for acid-resistant line pipe
A technology of high-strength steel plate and manufacturing method, applied in the direction of pipes/pipe joints/fittings, rigid pipes, manufacturing tools, etc., can solve the problem of reduced SSCC resistance, and achieve the effect of excellent HIC resistance and SSCC resistance.
Pending Publication Date: 2022-03-11
JFE STEEL CORP
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Problems solved by technology
In addition, when the steel plate is formed into a tubular shape, work hardening proceeds, so the hardness of the surface layer increases and the SSCC resistance decreases.
Method used
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[0099] Steels (steel grades A to W) having the composition shown in Table 1 were made into slabs by continuous casting, heated to the temperatures shown in Table 2, and then rolled at the end temperature and reduction shown in Table 2. Hot-rolled at a certain rate to produce steel sheets with the thicknesses shown in Table 2. Thereafter, the steel plates were controlled-cooled under the conditions shown in Table 2 using a water-cooled controlled cooling device. After that, the end of the steel plate is beveled, and after C-shaped, U-shaped, or O-shaped pressure is formed into a steel pipe shape, the butt joint between the inner surface and the outer surface is seam-welded by submerged arc welding. , and made into steel pipes through the pipe expansion process.
[0100] [organization specific]
[0101] The microstructure of the steel sheet obtained as described above was observed with an optical microscope and a scanning electron microscope. That is, a sample for metal struc...
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Abstract
Provided is a high-strength steel sheet for an acid-resistant line pipe, which not only has excellent HIC resistance, but also has excellent SSCC resistance in an environment including hydrogen sulfide of more than 1 bar and also has excellent SSCC resistance in an environment having a low hydrogen sulfide pressure of 1 bar. This high-strength steel sheet for an acid-resistant line pipe has a component composition containing, in mass%, 0.020-0.080% of C, 0.01-0.50% of Si, 0.50-1.80% of Mn, 0.015% or less of P, 0.0015% or less of S, 0.010-0.080% of Al, 0.0010-0.0080% of N, 0.01-0.50% of Mo, and 0.0005-0.0050% of Ca, with the remainder being Fe and unavoidable impurities, the steel structure located 0.25 mm below the surface of the steel sheet being a bainite structure, the bainite having an area ratio of crystal grains having a KAM value of 0.4 or more being 50% or less, and the thickness of the bainite being 0.5 mm or less. The Vickers maximum hardness at 0.25 mm below the surface of the steel sheet is 230 Hv or less, and the tensile strength is 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 used in the transportation of crude oil and natural gas, 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, line pipes can be manufactured by forming steel plates produced by slab mills, hot rolling mills into steel pipes through UOE forming, press bending, roll forming, and the like. [0003] Here, the line pipes used for the transportation of crude oil and natural gas containing hydrogen sulfide need not only strength, toughness, weldability, etc., but also resistance to hydrogen-induced cracking (HIC (Hydrogen Induced Cracking) resistance), resistance to sulfide stress corrosion cracking, etc. ...
Claims
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IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/12F16L9/02B21C37/02B21C37/06C21D8/02
CPCC22C38/02C22C38/04C22C38/06C22C38/12C22C38/002C22C38/001C21D8/0205C21D8/0226C21D8/0263B21C37/02B21C37/06F16L9/02C22C38/58C21D9/46C21D2211/002C21D2201/05C21D1/20C21D1/02C21D8/105C21D9/08C21D7/12C21D1/18C22C38/16C22C38/08C22C38/14C22C38/005C22C38/22C22C38/38C22C38/26C22C38/28C22C38/24C22C38/44C22C38/42C22C38/48C21D6/005C21D6/002C21D6/004C22C38/50C22C38/46
Inventor 泉大地嶋村纯二田村雄太井原宏一谷泽彰彦
Owner JFE STEEL CORP