High-strength thick steel plate with excellent drop weight characteristics

A drop hammer impact and high-strength technology, applied in the field of thick steel plates, can solve problems such as difficulties in high strength, and achieve good drop hammer impact characteristics and high strength effects

Inactive Publication Date: 2013-01-16
KOBE STEEL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in this technology, it is also difficult to increase the strength, and it is not possible to ensure good drop impact properties while maintaining high strength.

Method used

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  • High-strength thick steel plate with excellent drop weight characteristics
  • High-strength thick steel plate with excellent drop weight characteristics
  • High-strength thick steel plate with excellent drop weight characteristics

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0090] Various molten steels whose chemical compositions are shown in the following Tables 1 and 2 were smelted by a normal melting method, and the molten steel was cooled to form a slab (thickness: 300mm), and hot-rolled under the conditions shown in the following Tables 3 and 4. , cooled and tempered to obtain various steel plates (thickness: 100mm). In addition, in the following Tables 1 and 2, REM is added in the form of mischmetal containing about 50% of Ce and about 25% of La. In addition, in the following Tables 1 and 2, the column of "-" shows that no element was added.

[0091] 【Table 1】

[0092]

[0093] *: Impurities are unavoidable impurities other than iron, P and S

[0094] 【Table 2】

[0095]

[0096] *: The balance is iron and unavoidable impurities other than P and S

[0097] 【table 3】

[0098]

[0099] 【Table 4】

[0100]

[0101] For each of the obtained thick steel plates, the structure [bainite area fraction, bainite lath width, MA size (av...

Embodiment 2

[0132] Various molten steels having the chemical compositions shown in the following Table 7 were smelted by a common melting method, and the molten steel was cooled to form a slab (thickness: 300mm), and then hot rolled under the conditions shown in the following Table 8, and cooled and Tempering was performed to obtain various steel plates (thickness: 100 mm). In addition, in Tables 7 and 8, for reference, Test No. 24 shown in the aforementioned Tables 1, 3, and 5 is also shown.

[0133] 【Table 7】

[0134]

[0135] *: The balance is iron and unavoidable impurities other than P and S

[0136] 【Table 8】

[0137]

[0138] For each thick steel plate obtained, by the method shown in Example 1, the structure [area fraction of bainite, lath width of bainite, size of MA (average equivalent circle diameter and maximum equivalent circle diameter)], Mechanical properties (yield strength YS of thick steel plate, tensile strength TS, dart impact property NDT), and the size (aver...

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Abstract

The disclosed high-strength thick steel plate satisfies prescribed chemical component composition requirements, and is useful as a structural material in marine structures, ships, bridges, and also as a material in pressure vessels in nuclear power plants. In the microstructure positioned at a depth of t / 4-t / 2 from the surface (t is the plate thickness, same below), the area fraction of bainite is 90% or greater, the average value of the bainite lath width is 3.5 [mu]m or less, and the circle equivalent diameter of island martensite in the bainite has a maximum value of 3.0 [mu]m or less.

Description

technical field [0001] The present invention relates to a high-strength thick steel plate used as a raw material for pressure vessels of nuclear power plants in addition to structural materials for marine structures, ships, bridges, etc. thick steel plate. Background technique [0002] As a thick steel plate used for quenching / tempering (hereinafter referred to as "QT steel plate"), it has high strength, high toughness, and good weldability. Welded structures are widely used. Such QT steel sheets tend to require higher strength (for example, 415 MPa or more in terms of yield strength and 620 MPa or more in terms of tensile strength) with the recent increase in the design of welded structures. [0003] A thick steel plate needs to have high strength as a matter of course, and also needs to be excellent in the drop weight impact property which is an index of the brittle fracture property. However, the situation is accompanied by higher strength and thicker walls, and it is ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/38C22C38/58C21D8/02
CPCC21D2211/008C22C38/002C22C38/06C21D8/0226C22C38/12C22C38/04C22C38/001C21D8/0263C21D2211/002C21D8/02C22C38/38C22C38/58
Inventor 高冈宏行田村荣一
Owner KOBE STEEL LTD
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