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Steel plate excellent in toughness of large heat-input weld heat affected zone

A technology of welding heat impact and high heat energy, which is applied in the field of steel with improved toughness, can solve the problems of low desulfurization ability and high S content, and achieve the effect of improving HAZ toughness and excellent HAZ toughness

Inactive Publication Date: 2011-04-27
KOBE STEEL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in the era (1984-1985) when the technologies of Non-Patent Documents 1 and 2 were disclosed, the S content contained in the steel sheets disclosed in Non-Patent Documents 1 and 2 was large ( Specifically, above 0.0060%)

Method used

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  • Steel plate excellent in toughness of large heat-input weld heat affected zone
  • Steel plate excellent in toughness of large heat-input weld heat affected zone
  • Steel plate excellent in toughness of large heat-input weld heat affected zone

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0094] Melt steel with the composition shown in Table 1 or Table 2 below by a normal melting method (the balance is iron and unavoidable impurities), cast the molten steel to form a slab, and heat the slab to the temperature shown in Table 3 or Table 2. The temperature (measured value) shown in Table 4 is then hot-rolled to become a hot-rolled sheet with a thickness of 60mm. After the hot-rolling is completed, it is water-cooled and quenched to produce a tensile strength of 490-780MPa (50-80kg / mm 2 Grade) of various high-tensile steel plates (test panels). Also, in the steelmaking stage, the deoxidation time is 30 minutes.

[0095] In Table 1 and Table 2 below, REM is added in the form of misch metal containing about 50% of La and about 25% of Ce.

[0096] The heating temperature of the slab is controlled in consideration of the slab heating temperature (calculated value) calculated by Thermo-calc in relation to the amount of solid solution N as described above.

[0097] In ...

Embodiment 2

[0114] The HAZ toughness when the welding conditions were changed was evaluated for the steel sheet shown in Example 1 above.

[0115] Plates with a thickness of 25 mm were cut from various high-tensile steel plates (60 mm thick) obtained in Example 1 above, and the heat input was 15 kJ / mm, and gas-electric welding was performed to produce welded joints.

[0116] The other welding conditions are the same as in the above-mentioned Example 1.

[0117] On the obtained welded portion, the V-notch pendulum impact value (vE -55 ), to evaluate the HAZ toughness. The measurement results are collectively shown in Table 3 or Table 4 below. At this time, the V-notch pendulum impact value (vE -55 ) is more than 100J as qualified.

[0118] The steel materials (No. 1 to 29) of the present invention were welded at a heat input of 15 kJ / mm, and the HAZ toughness was still good. Therefore, the steel plates (No.1-29) of the present invention, no matter whether the high heat energy input we...

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Abstract

The invention provides a low S-containing steel sheet which has an S content reduced to about <=0.005% and can exhibit HAZ (heat affected zone) toughness not only when being subjected to ultrahigh heat input welding with a heat input volume, e.g., of >=60 kJ / mm, but also when being subjected to welding with a relatively high heat input volume, e.g., of >=15 kJ / mm. The steel sheet having a composition containing each of C, Mn, P, S, Al, Ti, N, Ca and O, and, if required, containing Si, and the balance iron with inevitable impurities, is characterized in that the content of solid solution N contained in the steel sheet is controlled to 0.0010 to 0.0060%.

Description

technical field [0001] The present invention relates to a steel plate suitable for welded structures such as ships, buildings, and marine structures, and more particularly to a steel material that improves the toughness of a steel plate during welding with a high heat input of about 15 kJ / mm or more. Background technique [0002] Structures in various fields such as ships, buildings, marine structures, etc. are generally constructed by welding and joining steel materials, but among the steel materials used in such structures, from the viewpoint of ensuring safety, of course, other than the steel materials themselves The strength of the welded part also requires good toughness. [0003] In addition, in recent years, along with the increase in size of welded structures, from the viewpoint of improvement in construction efficiency and cost reduction of structures, improvement in welding construction efficiency is required, which leads to increase in welding heat energy input. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/14
CPCC22C38/001C22C38/002C22C38/005C22C38/02C22C38/04C22C38/06C22C38/14
Inventor 武田裕之高冈宏行冈崎喜臣
Owner KOBE STEEL LTD
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