Steel plate for structural pipe, method for producing steel plate for structural pipe, and structural pipe
A technology for steel plates and pipes, applied in the field of structural pipes, can solve the problems of reduced strength and other mechanical properties, and achieve the effect of excellent strength
Inactive Publication Date: 2017-12-01
JFE STEEL CORP
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- Abstract
- Description
- Claims
- Application Information
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Problems solved by technology
During welding, PWHT (Post Weld Heat Treatment) is performed for the purpose of removing the residual stress of the forged product caused by welding, but mechanical properties such as strength may decrease due to heat treatment
Method used
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Embodiment
[0140] Steels having the composition shown in Table 1 (steel grades A to M, the remainder being iron and unavoidable impurities) were melted and cast into slabs by a continuous casting method. The obtained slabs were heated and hot-rolled, and then immediately cooled using a water-cooled accelerated cooling facility to manufacture steel sheets (No. 1 to 19) with a thickness of 20 mm. Table 2 shows the production conditions of the respective steel sheets. The area fractions of island martensite and bainite occupying the microstructure and the mechanical properties of each of the obtained steel sheets were evaluated by the methods described below. Table 3 shows the evaluation results.
[0141] For the area fraction of island martensite and bainite, 10 observations were randomly made on the surface of the sample taken from the center of the thickness of the plate after mirror grinding and nitric acid corrosion using a scanning electron microscope (2000 times magnification). Eva...
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Abstract
The present invention provides a steel plate for a structural pipe, said steel plate being a high-strength steel plate of API X100 grade or higher and, without the addition of a large quantity of alloy elements, having excellent strength in a rolling direction and having little difference in strength (excellent material uniformity) between the rolling direction and a direction perpendicular to the rolling direction. Specifically, this steel plate for a structural pipe has a specified composition and has a microstructure in which the area fraction of a bainite main component and island martensite is less than 3.0%, wherein the tensile strength in the rolling direction is 760 MPa or more, and an absolute value for the difference (TSC-TSL) between the tensile strength (TSC) in a direction orthogonal to the rolling direction and the tensile strength (TSL) in the rolling direction is 30 MPa or less.
Description
technical field [0001] The present invention relates to a steel plate for structural pipes, in particular, the invention relates to a steel plate for structural pipes with strength above API X100 and a small strength difference between the rolling direction and the rolling vertical direction and excellent material uniformity. [0002] In addition, the present invention relates to a method of manufacturing the above-mentioned steel plate for structural pipes and a structural pipe manufactured using the above-mentioned steel plate for structural pipes. Background technique [0003] Structural pipes such as conductor casing steel pipes and riser steel pipes are used in the excavation of oil or natural gas by a submarine resource drilling ship or the like. Among these applications, in recent years, the demand for high-strength steel pipes of API (American Petroleum Institute) grade X100 or higher has been increasing from the viewpoint of improvement of operating efficiency due t...
Claims
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Patent Timeline
Login to View More IPC IPC(8): C22C38/00C21D8/02C22C38/14C22C38/58
CPCC21D8/02C22C38/00C22C38/14C22C38/58C22C38/001C22C38/02C22C38/04C22C38/06C22C38/08C22C38/12C22C38/16C22C38/18C22C38/22C22C38/24C22C38/26C22C38/28C22C38/32C22C38/40C22C38/42C22C38/44C22C38/46C22C38/48C22C38/50C22C38/54C21D9/46C21D8/0226C21D8/0263C21D2211/001C21D2211/002C21D2211/008C22C38/002C22C38/005C22C38/38F16L9/02F16L9/17
Inventor 太田周作嶋村纯二石川信行远藤茂安田恭野
Owner JFE STEEL CORP