High-strength thick steel plate for construction having excellent characteristics for preventing diffusion of brittle cracks, and production method therefor

A technology of brittle crack propagation and stop characteristics, which is applied in the field of high-strength thick steel plates, can solve the problems of difficult control of production scale and large load, and achieve the effect of excellent brittle crack propagation stop characteristics and improved safety

Active Publication Date: 2014-08-27
JFE STEEL CORP
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Problems solved by technology

[0011] However, the steel materials with excellent brittle crack propagation arresting properties described in Patent Documents 1 and 2 obtained a specific structure by cooling only the surface layer of the steel material and then ...

Method used

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  • High-strength thick steel plate for construction having excellent characteristics for preventing diffusion of brittle cracks, and production method therefor
  • High-strength thick steel plate for construction having excellent characteristics for preventing diffusion of brittle cracks, and production method therefor
  • High-strength thick steel plate for construction having excellent characteristics for preventing diffusion of brittle cracks, and production method therefor

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Embodiment

[0110]The molten steel (steel codes A to O) of each composition shown in Table 1 is smelted in a converter, and made into a steel raw material (slab thickness 250 mm) by continuous casting, hot rolled to a plate thickness of 50 to 80 mm, and then cooled. The test steels No. 1-29 were obtained. For some, tempering was also performed after cooling. Table 2 shows hot rolling conditions, cooling conditions, and tempering conditions.

[0111] For the obtained thick steel plate, a Φ14 JIS14A test piece was cut from 1 / 4 of the plate thickness so that the longitudinal direction of the test piece was at right angles to the rolling direction, and a tensile test was performed to measure the yield point (Yield Strength) , Tensile Strength.

[0112] In addition, a JIS No. 4 impact test piece was cut out from the surface layer and the middle part of the plate thickness (hereinafter also referred to as 1 / 2t part) so that the direction of the major axis of the test piece was parallel to the...

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Abstract

Provided are: a high-strength thick steel plate for construction having excellent characteristics for preventing the diffusion of brittle cracks, said plate being used for ships and having a preferred plate thickness of at least 50 mm; and a method for producing the thick steel plate. The thick steel plate has excellent characteristics for preventing the diffusion of brittle cracks, characterized in that: the thick steel sheet has a specific component composition; the main constituent of the metal structure is a ferrite phase; the thick metal sheet has an aggregate structure in which the density (I) in the RD//(110) plane at the plate thickness surface is at least 1.3, and the density (I) in the RD//(110) plane at the plate thickness center is at least 1.8; the Charpy fracture appearance transition temperature (vTrs) at the surface is not more than -60 DEG C, and the Charpy fracture appearance transition temperature (vTrs) at the plate thickness center is not more than -50 DEG C.

Description

technical field [0001] The present invention relates to a high-strength thick steel plate for structural use excellent in brittle crack arrestability (brittle crack arrestability) and a manufacturing method thereof, and particularly relates to a plate with a thickness of 50 mm or more suitable for ships high-strength thick steel plate. Background technique [0002] For large structures such as ships, accidents caused by brittle fractures have a great impact on the economy and the environment. Therefore, it is generally required to improve safety, and toughness at operating temperatures is required for the steel materials used (toughness), and brittle crack propagation stop characteristics. [0003] Vessels such as container ships and bulk carriers use high-strength thick-walled materials for outer plate of ship's hull in their structures. Recently, along with the increase in the size of the hull, high-strength and thicker walls are further developed. In general, the britt...

Claims

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Application Information

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IPC IPC(8): C22C38/14C22C38/58C21D8/02
CPCC21D8/0263C22C38/14C22C38/04C22C38/06C22C38/58C21D8/0205C22C38/001C21D2211/005C22C38/18C21D8/02C22C38/02C21D8/0226C21D2201/05C22C38/00
Inventor 竹内佳子长谷和邦三田尾真司村上善明
Owner JFE STEEL CORP
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