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High strength thick steel plate with superior brittle crack arrestability for high heat input welding and method for manufacturing same

A technology of high-energy welding and brittle crack propagation, applied in the field of high-strength steel plates, can solve the problems of difficult control of production scale, and achieve the effect of excellent brittle crack propagation stop characteristics and improved safety.

Active Publication Date: 2015-11-25
JFE STEEL CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0011] However, the steel materials described in Patent Documents 1 and 2 which are excellent in brittle crack propagation arresting properties obtain a specific structure by reheating only the thick surface layer of the steel material once and then performing processing during the reheating. Therefore, Difficult to control at actual production scale

Method used

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  • High strength thick steel plate with superior brittle crack arrestability for high heat input welding and method for manufacturing same
  • High strength thick steel plate with superior brittle crack arrestability for high heat input welding and method for manufacturing same
  • High strength thick steel plate with superior brittle crack arrestability for high heat input welding and method for manufacturing same

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Embodiment

[0138] The molten steel (steel codes A to R) 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. 1-30 were obtained. For some, tempering was also performed after cooling. Table 2 shows hot rolling conditions, cooling conditions, and tempering conditions.

[0139]

[0140] Table 2

[0141]

[0142] Note 1: The underline indicates that it is outside the scope of the present invention.

[0143] Note 2: "Cumulative reduction rate in the recrystallization γ zone" refers to the cumulative reduction rate in the central part of the plate thickness in the state of the austenite recrystallization temperature zone.

[0144] Note 3: "Average reduction ratio in the recrystallization γ region" refers to the average reduction ratio per pass in the state where the central part of the plate thickness is in th...

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Abstract

Provided are a high strength thick steel plate, which has superior brittle crack arrestability for high heat input welding that has a plate thickness of 50 mm or greater and is suitably used in marine vessels, and a manufacturing method for the same. The present invention is a thick steel plate and a manufacturing method for the same, wherein the thick steel plate has: a specific component composition, a metal structure composed mainly of ferrite, and an aggregate structure in which the density at the RD / / (110) plane at the surface layer of the plate thickness is 1.3 or greater and the density at the RD / / (110) plane in the center part of the plate thickness is 1.8 or greater. Charpy fracture appearance transition temperature (vTrs) is −50°C or less at the surface layer and in the center part of the plate thickness.

Description

technical field [0001] The present invention relates to a high-strength thick steel plate for high heat input welding with excellent brittle crack arrestability (brittle crack arrestability) and a manufacturing method thereof, in particular to a high-strength steel plate suitable for use in ships with a plate thickness of 50 mm or more. 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, improvement of safety is generally required, and the toughness at service temperature and brittle crack propagation stop characteristic are required for the steel material to be used. [0003] Ships such as container ships and bulk carriers use high-strength thick-walled materials for outer plate of ship'shull in their structures. Recently, along with the enlargement of ship hulls, high-strength and thick-walled materials are further developed. In general, the brittle crack...

Claims

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Application Information

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IPC IPC(8): C22C38/00C21D1/26C21D8/02C22C38/14C22C38/58
CPCC21D1/26C21D8/02C22C38/00C22C38/04C22C38/14C22C38/58C21D8/0226C21D2201/05C21D2211/004C21D2211/005C21D2211/008C22C38/001C22C38/002
Inventor 中岛孝一竹内佳子长谷和邦三田尾真司
Owner JFE STEEL CORP
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