Expandable high-strength steel material and expanded high-strength steel pipe having excellent expansibility and crush strength, and manufacturing method thereof

A high-strength, expansive technology, applied in the field of high-strength steel and expansive high-strength steel pipe, high-strength steel pipe manufacturing, can solve the problems of low expansiveness, application limitations, difficulty in obtaining strength, etc.

Inactive Publication Date: 2018-09-21
POHANG IRON & STEEL CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the application of the carbon steel disclosed in Patent Document 1 as an expandable steel material is limited because the disclosed carbon steel has low expansibility below the level of about 20%.
In addition, it is difficult to obtain the desired strength after the expansion of carbon steel, and due to the Bauschinger effect, the crush strength of carbon steel is low

Method used

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  • Expandable high-strength steel material and expanded high-strength steel pipe having excellent expansibility and crush strength, and manufacturing method thereof
  • Expandable high-strength steel material and expanded high-strength steel pipe having excellent expansibility and crush strength, and manufacturing method thereof
  • Expandable high-strength steel material and expanded high-strength steel pipe having excellent expansibility and crush strength, and manufacturing method thereof

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Embodiment Construction

[0018] The inventors conducted research on methods for solving the problems of existing expandable steel materials, and obtained the following knowledge. High manganese steel, which is an austenitic steel material, has a high level of uniform elongation, and thus high manganese steel has high expansibility. However, the stability of austenite in the negative segregation zone of high manganese steel is low due to the alloy composition difference between the negative segregation zone and the positive segregation zone. Therefore, if the austenite formed in the negative segregation region is deformed due to expansion, and thus transformed into martensite, many dislocations are formed, and this dislocation weakens the Bauschinger effect. Based on these findings, the inventors have invented the present invention.

[0019] Exemplary embodiments of the present invention will now be described.

[0020] Manganese (Mn): 12wt% to 18wt%.

[0021] As a representative element for stabiliz...

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Abstract

The present invention provides an expandable high-strength steel material and an expanded high-strength steel pipe having excellent expansibility and crush resistance, and a manufacturing method of the expandable high-strength steel material and the expanded high-strength steel pipe. The expandable high-strength steel contains, by weight, manganese (Mn): 12% to 18%, carbon (C): 0.3% to 0.6%, and the balance of iron and unavoidable impurities, wherein carbon (C ) and manganese (Mn) satisfy the following conditions: 23≤35.5C+Mn≤38. Before expansion, the expandable high-strength steel has an austenitic single-phase microstructure; after expansion, the expandable high-strength steel has martensite comprising 5 to 50 area % and 50 to 95 area % % austenitic microstructure.

Description

technical field [0001] The present invention relates to an expandable high-strength steel material and an expanded high-strength steel pipe having excellent expansibility and crush resistance, and a manufacturing method of the expandable high-strength steel material and the expanded high-strength steel pipe. Background technique [0002] Generally, when installing steel pipes below the earth's surface in an oil field (underground), a hole is first drilled to a predetermined depth in the ground, and a steel pipe portion called a "casing" is installed therein to prevent the hole from collapsing. Thereafter, further holes are drilled from the lower end of the casing to form a deeper well, and a new casing is installed through the previously installed casing. This work is repeated to finally connect the well tubing (pipe) to the oil formation. If drilling very deep wells, various casings with different diameters are used. Since the diameter of the oil well pipe through which o...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/04C22C38/20C22C38/38C21D8/02
CPCC21D8/02C22C38/04C22C38/20C22C38/38C22C38/02C21D6/005C21D8/0226C21D8/0263C21D8/105C21D9/08C21D2211/001C21D2211/008C21D9/46C22C38/16F16L9/02
Inventor 李学哲徐仁植李淳基李弘周
Owner POHANG IRON & STEEL CO LTD
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