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Tenacity excellent high intensity steel for welding heat influenced part

A technology for welding heat-affected zones and thick steel plates. It is applied in the field of steel plates and can solve problems such as inability to ensure toughness and low-temperature toughness reduction.

Inactive Publication Date: 2011-03-16
KOBE STEEL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] In addition, the low-temperature toughness of the central part of the steel plate (base material) with reduced reduction has also been pointed out.
In order to improve the toughness of the base material, it is known that the effective method is to lower the finish rolling temperature, but as the thickness of the steel plate increases, there is a problem that sufficient toughness cannot be ensured when the plate thickness becomes 80mm or more.

Method used

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  • Tenacity excellent high intensity steel for welding heat influenced part
  • Tenacity excellent high intensity steel for welding heat influenced part
  • Tenacity excellent high intensity steel for welding heat influenced part

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0080] According to the usual smelting method, the steel with the composition shown in the following Table 1 is smelted, and the molten steel is cooled while controlling the cooling rate during casting (temperature range of 1500 to 1300° C.) to form a slab (cross-sectional shape: 200mm×250mm ), heated to 1100° C. and hot-rolled to obtain a hot-rolled sheet having a thickness of 50 mm, and was air-cooled after rolling to obtain a test sheet. In addition, in Table 1, REM is added in the form of misch metal containing about 50% of La and about 25% of Ce. In addition, "-" in Table 1 indicates that no element was added.

[0081] Form 1

[0082]

[0083] * Balance: Fe and unavoidable impurities.

[0084] For each test plate manufactured as above, the number density of its Ti-containing nitrides was measured according to the following method (the number of Ti-containing nitrides with a circle equivalent diameter of 0.05 μm or less, and the number of Ti nitrides with a circle eq...

Embodiment 2

[0104] The amount of dissolved oxygen in molten steel is controlled according to the amount of Si and Mn added, and the steel with the composition shown in Table 3 below is smelted by the melting method, and the cooling rate during casting (temperature range of 1500 to 1300°C) is controlled. At the same time, the molten steel is cooled to become a slab (cross-sectional shape: 200mm×250mm), heated to 1100°C and hot-rolled to become a hot-rolled sheet with a thickness of 80mm, and directly quenched after rolling, at 500°C Tempering was performed to obtain a test panel. In addition, in Table 3, REM is added in the form of misch metal containing about 50% of La and about 25% of Ce. In addition, "-" in Table 1 indicates that no element was added.

[0105] Form 3

[0106]

[0107] * 余 Quantity: Fe and unavoidable impurities.

[0108] For each test plate manufactured in the above-mentioned manner, in the same manner as in Example 1, the number density of its Ti-containing nitr...

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Abstract

The invention relates to a thick steel plate which has an excellent HAZ tenacity even being welded with high heat energy. The invention comprises 0.03 to 0.12 percents of C, less than 0.2 percents (including 0 percent) of Si, 1.0 to 2.0 percents of Mn, less than 0.03 percents (excluding 0 percent) of P, less than 0.015 percents (excluding 0 percent) of S, less than 0.10 percents (excluding 0 percent) of Al, 0.015 to 0.08 percents of Ti, 0.0060 to 0.0120 percents of N, 0.0010 to 0.0050 percents of B, and 0.005 to 0.020 percents of Nb and / or 0.0001 to 0.050 percents of Zr, satisfying the relation in the formula (I); and the invention is less than 0.05um and includes more than 5.0*106 of Ti nitride per 1mm2 in the equivalent circle diameter. The value of [Ti] *16[Si] * (12-40[C]) is less than 0.38(%) to (1), wherein, [Ti], [Si] and [C] respectively present the contents (quality percent) of Ti, Si and C.

Description

technical field [0001] The present invention relates to steel plates suitable for welded structures such as bridges, high-rise buildings, and ships, and in particular to steel plates with excellent toughness in the heat-affected zone (hereinafter simply referred to as "HAZ") after high-heat energy welding. Background technique [0002] In recent years, with the increase in size of the various welded structures described above, welding of thick steel plates having a plate thickness of 50 mm or more is unavoidable. Therefore, in all fields, from the standpoint of improving welding work efficiency, there is a situation where high heat energy welding with heat energy of 50 kJ / mm or more is directed. [0003] However, if high heat energy welding is performed, the HAZ is added to the high-temperature austenite region and then slowly cooled, so the structure of the HAZ (especially near the fusion zone of the HAZ) is coarsened, and there is a problem that the toughness of this part ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/14
Inventor 冈崎喜臣高冈宏行名古秀德出浦哲史杉村朋子
Owner KOBE STEEL LTD
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