High-strength steel plate for high heat input welding excellent in brittle crack propagation stop characteristic and manufacturing method thereof

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

Active Publication Date: 2018-01-05
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 steel plate for high heat input welding excellent in brittle crack propagation stop characteristic and manufacturing method thereof
  • High-strength steel plate for high heat input welding excellent in brittle crack propagation stop characteristic and manufacturing method thereof
  • High-strength steel plate for high heat input welding excellent in brittle crack propagation stop characteristic and manufacturing method thereof

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Experimental program
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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 range.

[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 t...

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Abstract

The present invention provides a high-strength steel plate for high heat input welding, which is suitable for ships with a plate thickness of 50 mm or more, and has excellent brittle crack propagation stop characteristics, and a manufacturing method thereof. A thick steel plate having a specific composition, a metal structure mainly composed of a ferrite phase, and a concentration degree of RD / / (110) planes in the thick surface portion of the plate being 1.3, and a method for manufacturing the same. In the texture above, the degree of concentration of the RD / / (110) plane in the thickness center part is 1.8 or more, and the Charpy fracture transition temperature vTrs of the thickness surface part and the thickness center part is -50°C or less.

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, and particularly relates to a plate thickness suitable for use in ships High strength steel plate above 50mm. 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] Vessels such as container ships and bulk carriers use high-strength thick-walled materials for outer plates of ship's hulls in their structures. Recently, along with the enlargement of ship hulls, high-strength and thick-walled materials are further developed. In general, the brittle c...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/00C21D1/26C21D8/02C22C38/14C22C38/58
CPCC21D1/26C21D8/0226C21D2201/05C21D2211/004C21D2211/005C21D2211/008C22C38/04C22C38/14C22C38/58C21D8/02C22C38/00C22C38/001C22C38/002
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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