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High tensile strength steel and marine structure having excellent weld toughness

a high tensile strength steel and marine structure technology, applied in the field of high tensile strength steel and a marine structure, can solve the problems of increasing the amount of solid solution n, affecting the welding efficiency of marine structures, so as to achieve excellent weldability, increase the efficiency and safety of on-site welding, and improve the effect of tensile strength

Inactive Publication Date: 2010-09-09
KAMO TAKAHIRO +4
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The solution results in a steel with improved weldability and toughness, enabling efficient and safe welding of thick plates with high heat input, thus reducing construction costs and ensuring structural integrity in extreme marine conditions.

Problems solved by technology

This is thought to be because when the N / Al ratio is too small, coarse AlN precipitates, and not only does this itself have an adverse effect on toughness, but also it impedes fine dispersion of TiN in large amounts.
On the other hand, if the N / Al ratio is too large, the amount of solid solution N increases, and the density of AlN and TiN dispersed in the steel becomes very small.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

examples

[0097]In this example, steel slabs having a thickness of 300 mm and having the chemical compositions shown in Table 1 and Table 2 were prepared by continuous casting. In order to control inclusions at the center of the thickness of a steel plate, during continuous casting, the temperature of molten steel was not made too high, and the difference thereof from the solidification temperature which was determined by the molten steel composition was controlled so as to be at most 50° C., and electromagnetic stirring just before solidification and reduction in thickness at the time of solidification were carried out.

[0098]Table 3 and Table 4 show the working conditions of steel slabs having the chemical compositions shown in Table 1 and Table 2. The working conditions shown in Table 3 and Table 4 are for the steel slabs having the chemical compositions shown in Table 1 and Table 2, respectively.

[0099]After a slab with a thickness of 300 mm was heated at the indicated heating temperature f...

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PUM

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Abstract

In order to provide a high tensile strength steel having excellent low temperature toughness and which can withstand large heat input welding, a steel comprises, in mass percent, C: 0.01-0.10%, Si: at most 0.5%, Mn: 0.8-1.8%, P: at most 0.020%, S: at most 0.01%, Cu: 0.8-1.5%, Ni: 0.2-1.5%, Al: 0.001-0.05%, N: 0.0030-0.0080%, O: 0.0005-0.0035%, if necessary at least one of Ti: 0.005-0.03%, Nb: 0.003-0.03%, and Mo: 0.1-0.8%, and a remainder of Fe and impurities, and the N / Al ratio is 0.3-3.0.

Description

[0001]This is a continuation in part of application Ser. No. 11 / 443,849 filed on May 26, 2006, which is a continuation of International Patent Application No. PCT / W2004 / 017575, filed Nov. 26, 2004. The PCT application was not in English as published under PCT Article 21(2).TECHNICAL FIELD[0002]The present invention relates to a high tensile strength steel and a marine structure, and particularly to a high tensile strength steel for welding and a marine structure having excellent weld toughness.[0003]More specifically, the present invention relates to a high tensile strength steel for welding for use in welded structures such as buildings, civil engineering projects, construction equipment, ships, pipes, tanks, and marine structures, and particularly to a high tensile strength steel for welding to construct marine structures as well as to a marine structure thus constructed. For example, it relates to a thick, high strength steel plate with a thickness of at least 50 mm and a yield s...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C22C38/42C22C38/16C22C38/08C22C38/02C22C38/04C22C38/06C22C38/14C22C38/20C21D8/02C22C38/00C22C38/58
CPCC22C38/02C22C38/48C22C38/44C22C38/42C22C38/001C22C38/002C22C38/005C22C38/58
Inventor KAMO, TAKAHIROURABE, TAKESHINAKAMURA, HIROFUMIOHNISHI, KAZUSHIHAMADA, MASAHIKO
Owner KAMO TAKAHIRO