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Steel plate having low yield ratio, high strength and high uniform elongation and method for producing same

一种均匀伸长、低屈服比的技术,应用在具有低屈服比、高强度以及高均匀伸长率的钢板及其制造领域,能够解决屈服应力升高等问题,达到提高生产率以及经济性的效果

Active Publication Date: 2012-07-04
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] On the other hand, welded steel pipes such as UOE steel pipes and electric welded steel pipes used for line pipes have the following problems. After forming the steel plate into a tubular shape in a cold environment, after welding the abutting surface, usually from corrosion prevention From the viewpoint of steel pipes, polyethylene coating or powder epoxy coating is applied to the outer surface of steel pipes. heating, strain aging occurs, yield stress rises, and the yield ratio in the steel pipe will be larger than that in the steel plate

Method used

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  • Steel plate having low yield ratio, high strength and high uniform elongation and method for producing same
  • Steel plate having low yield ratio, high strength and high uniform elongation and method for producing same
  • Steel plate having low yield ratio, high strength and high uniform elongation and method for producing same

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Embodiment 1

[0136] Steels (steel types A to J) having the composition shown in Table 1 were formed into slabs by a continuous casting method to manufacture thick steel plates (No. 1 to 16) with a plate thickness of 20 and 33 mm.

[0137] The heated slab is rolled by hot rolling, then immediately cooled using a water-cooled accelerated cooling device, and reheated using an induction heating furnace or a gas combustion furnace. The induction heating furnace is installed on the same production line as the accelerated cooling equipment.

[0138] Table 2 shows the production conditions of the respective steel sheets (No. 1 to 16). In addition, temperature, such as heating temperature, rolling completion temperature, cooling stop (finishing) temperature, and reheating temperature, was made into the average temperature of a steel plate. The average temperature is calculated from the surface temperature of the billet or steel plate using parameters such as plate thickness and thermal conductivit...

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Abstract

Disclosed are a steel plate, which shows an excellent aging treatment resistance of API 5L X70 grade or lower and has a low yield ratio, a high strength and a high uniform elongation, and a method for producing the same. Specifically disclosed is a steel plate showing an excellent strain aging resistance and having a low yield ratio, a high strength and a high uniform elongation, which comprises, in terms of mass%, 0.06-0.12% of C, 0.01-1.0% of Si, 1.2-3.0% of Mn, 0.015% or less of P, 0.005% or less of S, 0.08% or less of Al, 0.005-0.07% of Nb, 0.005-0.025% of Ti, 0.010% or less of N, 0.005% or less of O, and Fe and unavoidable impurities as the remainder, and the metal tissue of which consists of two phases of bainite and island martensite wherein the area proportion of the island martensite is 3-20% and the circle-equivalent diameter thereof is 3.0 [mu]m or less, characterized in that the uniform elongation of the steel plate before and after a strain aging treatment for 30 minutes or shorter at a temperature of 250oC or lower is 7% or more and the yield ratio thereof is 85% or less.

Description

technical field [0001] The present invention relates to a low yield ratio, high strength and high uniform elongation steel plate mainly suitable for use in the field of line pipes, and a manufacturing method thereof , especially to a steel plate having low yield ratio, high strength, and high uniform elongation excellent in strain aging resistance, and a method for producing the same. In addition, the uniform elongation mentioned here is also called uniform elongation, and means the critical value of permanent elongation at which the parallel part of a test piece deforms substantially uniformly in a tensile test. Usually, it is obtained as the permanent elongation corresponding to the maximum tensile load. Background technique [0002] In recent years, in steel materials for welded structures, in addition to high strength and high toughness, low yield ratio and high uniform elongation are required from the viewpoint of earthquake resistance (earthquake-proof). For example,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C21D8/02C22C38/14C22C38/58
CPCC22C38/14C21D2211/008C21D8/0226C22C38/12C21D8/0263C21D2211/002C22C38/001C22C38/002C22C38/02C22C38/04C22C38/06C22C38/08C22C38/16C22C38/18
Inventor 岛村纯二石川信行鹿内伸夫
Owner JFE STEEL CORP
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