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Steel pipe for steel plate and line pipe and manufacturing method thereof

A manufacturing method and technology for steel plates, which can be applied to manufacturing tools, furnaces, heat treatment equipment, etc., can solve problems such as uncontrollable bubble size, uncompressed bubbles, and insufficient suppression of HIC, and achieve excellent resistance to hydrogen-induced cracking. Effect

Active Publication Date: 2021-06-18
KOBE STEEL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] However, in Patent Document 1, the study was conducted to reduce the number of air cells in the slab, but the uncompressed air cells in the steel material of the final product were not considered.
Therefore, defects caused by uncompressed air bubbles remaining in the steel cannot be controlled, and HIC caused by uncompressed air bubbles cannot be suppressed.
[0010] In addition, in the method of Patent Document 2, although the study of reducing the content of Ar gas bubbles in the steel material was carried out, the size of the bubbles and the uncompressed bubbles of the steel material were not considered.
Therefore, even a small amount of coarse Ar bubbles cannot sufficiently suppress HIC.

Method used

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  • Steel pipe for steel plate and line pipe and manufacturing method thereof
  • Steel pipe for steel plate and line pipe and manufacturing method thereof
  • Steel pipe for steel plate and line pipe and manufacturing method thereof

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Embodiment Construction

[0024] In order to solve the above-mentioned problems, the present inventors compared the CLR (ClackLength Ratio, the ratio of the total crack length to the width of the test piece [%], the crack length ratio) of the surface layer measured by the HIC test with that measured by the ultrasonic flaw detection test. The inter-correlation of the internal defects of the steel plate was intensively studied. As a result, it was found that the chemical composition of the steel plate is controlled within a specified range so that the contents of Ca, S, and O satisfy a specified relational expression, and the area ratio of the portion with a defect echo height of 20% or more is 0.05% or less. By controlling internal defects, excellent HIC resistance can be obtained.

[0025] Hereinafter, the steel plate according to the embodiment of the present invention and its manufacturing method will be described in detail.

[0026]

[0027] (1-1. Chemical Composition)

[0028] The steel plate a...

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Abstract

A steel plate containing C: 0.02 to 0.15% by mass, Si: 0.02 to 0.50% by mass, Mn: 0.6 to 2.0% by mass, P: more than 0 mass% but not more than 0.030 mass%, S: more than 0 Mass % but less than 0.003 mass %, Al: 0.010 to 0.080 mass %, Ca: 0.0003 to 0.0060 mass %, N: 0.001 to 0.01 mass %, and O: more than 0 mass % but less than 0.0045 mass %, and satisfy In the following (1) formula and the following (2) formula, the balance is composed of iron and unavoidable impurities, and the area ratio of the part with a defect echo height of 20% or more is 0.05% or less. 3.0≤[Ca] / [S](1), ([Ca]-1.25×[S]) / [O]≤1.80(2) Here, [Ca], [S] and [O] are respectively Ca , S and O content (mass%).

Description

technical field [0001] The present invention relates to a steel pipe for steel plates and line pipes and a method of manufacturing the same. Background technique [0002] Mainly in line pipes for transportation of oil and gas, and storage containers, so-called sulfur resistance, such as hydrogen induced cracking resistance and stress corrosion cracking resistance, is required along with the development of low-quality resources containing hydrogen sulfide. It is known that hydrogen induced cracking (Hydrogen Induced Cracking, hereinafter referred to as "HIC") is the intrusion of hydrogen into the interior of the steel along with the corrosion reaction caused by the above-mentioned hydrogen sulfide, and the non-metallic inclusions such as MnS and Nb (C, N) Defects such as objects gather and gasify, resulting in cracks. When HIC occurs, there is a problem that the toughness of the structure decreases. In particular, since hydrogen penetrates from the surface portion of the st...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/00B22D11/00B22D11/10C22C38/06C22C38/58C21D8/02
CPCB22D11/10C21D8/02C22C38/06B22D11/001C22C38/02C22C38/04C22C38/005C22C38/002C22C38/42C22C38/44C22C38/46C22C38/48C22C38/50C21D9/08C21D8/0263C22C38/54C22C38/001C21D8/0205C21D8/0226C21D9/0081
Inventor 田代喜一郎柿崎元树
Owner KOBE STEEL LTD
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