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Ultra-thick structural steel having excellent brittle crack initiation resistance, and manufacturing method therefor

A kind of steel and brittle cracking technology, applied in the field of ultra-thick structural steel and its manufacturing

Pending Publication Date: 2021-08-10
浦项股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Regrettably, such efforts may be somewhat helpful in improving the resistance to brittle crack initiation in the weld zone, but may not be the fundamental countermeasure for residual defects that have a major impact on the reduction in brittle crack initiation resistance

Method used

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  • Ultra-thick structural steel having excellent brittle crack initiation resistance, and manufacturing method therefor
  • Ultra-thick structural steel having excellent brittle crack initiation resistance, and manufacturing method therefor

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach

[0050] Hereinafter, the present disclosure will be described in more detail through examples. It should be noted, however, that the following examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the present disclosure can be determined by the matters described in the claims and matters that can be reasonably inferred therefrom.

Embodiment approach

[0052] The molten steel was refined for the RH refining time of Table 1 to prepare molten steel having the alloy composition of Table 1 . The prepared molten steel was continuously cast to produce a billet having a thickness of 400 mm. The billet was reheated to a temperature of 1080°C, and then rough-rolled at a temperature of 1030°C to prepare a bar having a thickness of 200 mm. The cumulative reduction applied during rough rolling was 50%. After the rough rolling, the bars were finish-rolled in a temperature range of 700°C to 850°C to obtain hot-rolled steel products having thicknesses in Table 2, and then cooled under the conditions listed in Table 2.

[0053] The microstructure, yield strength, and impact transition temperature of the center portion of the steel material manufactured in the above manner were measured, and the measurement results are listed in Table 2. In addition, the total thickness CTOD test was performed on the steel at -10°C, and the test results ar...

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Abstract

One embodiment of the present invention provides an ultra-thick structural steel having excellent brittle crack initiation resistance, and a manufacturing method therefor, the ultra-thick structural steel comprising, by wt%, 0.03-0.08% of C, 1.6-2.2% of Mn, 0.6-1.3% of Ni, 0.005-0.03% of Nb, 0.005-0.02% of Ti, 0.1-0.4% of Cu, 100 ppm or less of P, 40 ppm or less of S, 1.5 ppm or less of H, and the balance of Fe and other inevitable impurities, wherein the sum of acicular ferrite and granular bainite in the microstructure is 80% or more by area fraction, the sum of the total length of cracks having a size of 30 [Mu]m or more per unit area of 1 mm<2> in a + / -1 mm region on the basis of the thickness center of the steel is 130 [Mu]m or less, and the yield strength is 500 MPa or more.

Description

technical field [0001] The present disclosure relates to an ultra-thick structural steel material with excellent resistance to brittle crack initiation and a method of manufacturing the same. Background technique [0002] In recent years, the development of ultra-thick high-strength steel has been required in terms of structural design used in domestic and foreign shipbuilding industries, etc. When high-strength steels are used to design structures, such structures can be lightened for economical benefits, and steel plates can be thinned to simultaneously ensure ease of machining and welding operations. [0003] Generally, when ultra-thick steel plates are used to manufacture high-strength steels, the overall structure may be insufficiently deformed due to the increase in total reduction. Therefore, the structure may become coarse, and a difference between the cooling rate of the surface portion and the central portion may occur due to the large thickness during quenching, ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/04C22C38/08C22C38/12C22C38/14C22C38/16C21D8/02B21B3/00B21B37/16
CPCC22C38/04C22C38/08C22C38/12C22C38/14C22C38/16C21D9/46C21D2211/005C21D2211/002C21D8/005C21D8/0226C21D8/0263C21D1/02C21D8/021Y02P10/20B21B3/003B21B37/16C21D6/001C21D6/005C21D8/0205C21D2211/001C21D2211/008C21D2211/009C22C38/002
Inventor 李学哲
Owner 浦项股份有限公司
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