High-strength steel having superior brittle crack arrestability, and production method therefor

A technology of crack propagation and manufacturing method, which is applied in the field of high-strength steel and its manufacturing, can solve the problems of reduced productivity, can not be said to solve the problems of brittle crack growth resistance, and is not suitable for commercial applications, so as to achieve high yield strength and brittle resistance Excellent crack growth effect

Active Publication Date: 2017-08-29
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

[0008] However, although this technology contributes to the finer structure of the surface layer, it cannot solve the problem of low impact toughness due to the coarse structure of the central part, so it cannot be said to be a fundamental measure to solve the resistance to brittle crack growth.
[0009] Moreover, it is expected that the productivity will drop significantly when the technology itself is applied to a general mass production system, so it can be said that the technology is not suitable for commercial application

Method used

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  • High-strength steel having superior brittle crack arrestability, and production method therefor
  • High-strength steel having superior brittle crack arrestability, and production method therefor
  • High-strength steel having superior brittle crack arrestability, and production method therefor

Examples

Experimental program
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Effect test

Embodiment 1

[0132] After reheating at a temperature of 1050°C, a steel slab having a thickness of 400 mm and having the composition shown in Table 1 below was subjected to rough rolling at a temperature of 1020°C to produce rods. The average temperature difference between the surface and center of the slab during rough rolling is shown in Table 2 below. The cumulative reduction ratio was 50%, and the same reduction ratio was used.

[0133] The average temperature difference between the center and the surface during rough rolling in Table 2 represents the actual measured surface temperature of the slab or bar before rough rolling and the center calculated by considering the moisture content sprayed onto the bar and the thickness of the slab before rough rolling. The temperature difference is the result of measuring the temperature difference of each rough rolling pass and calculating the overall average value.

[0134] The thickness of the rough-rolled bar is 180 mm, and the grain size aft...

Embodiment 2

[0154] As shown in Table 3, except that the Cu / Ni weight ratio of the steel slab was changed, steel plates were produced with the same composition and production conditions as Invention Steel 2 in Example 1, and the surface of the produced steel plates were investigated. properties, and the results are shown in Table 3.

[0155] The surface properties of the steel sheets in Table 3 below were measured to determine whether or not star cracks occurred in the surface portion due to hot shortness.

[0156] table 3

[0157]

[0158] As shown in Table 3, it can be seen that when the Cu / Ni weight ratio is properly controlled, the surface characteristics of the steel sheet are improved.

Embodiment 3

[0160] As shown in FIG. 4 , except that the grain size (μm) after rough rolling and before finish rolling was changed, steel sheets were produced with the same composition and production conditions as Invention Steel 1 in Example 1, and the produced steel sheets were investigated. Table 4 shows the average characteristics of the grain size at the center of the steel sheet and the results.

[0161] Table 4

[0162] steel type

[0163] As shown in Table 4, it can be seen that the smaller the grain size of the central portion of the rod after rough rolling becomes, the finer the average grain size of the central portion becomes, and thus it is expected that the resistance to brittle crack growth is improved.

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PUM

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Abstract

The present invention provides high-strength steel having superior brittle crack arrestability and a production method therefor. Provided according to the present invention are: high-strength steel, which has superior brittle crack arrestability, comprises 0.05-0.1 wt% of C, 0.9-1.5 wt% of Mn, 0.8-1.5 wt% of Ni, 0.005-0.1 wt% of Nb, 0.005-0.1 wt% of Ti, 0.1-0.6 wt% of Cu, 0.1-0.4 wt% of Si, at most 100 ppm of P, and at most 40 ppm of S with the remainder being Fe and other inevitable impurities, and has microstructures including one structure selected from the group consisting of a single-phase structure of ferrite, a single-phase structure of bainite, a complex-phase structure of ferrite and bainite, a complex-phase structure of ferrite and pearlite, and a complex-phase structure of ferrite, bainite, and pearlite; and a production method therefor. According to the present invention, high-strength steel having high yield strength and superior brittle crack arrestability can be obtained.

Description

technical field [0001] The present invention relates to a high-strength steel excellent in brittle crack growth resistance and a manufacturing method thereof. Background technique [0002] Recently, in the design of structures used in domestic and foreign ships, marine, construction, and civil engineering fields, the development of ultra-thick plate steel with high strength characteristics is required. [0003] In the case of using high-strength steel when designing a structure, the shape of the structure can be reduced in weight, so not only can economic benefits be obtained, but also the thickness of the steel plate can be thinned, so that processing and welding operations can be ensured at the same time convenience. [0004] For high-strength steel, in general, when producing ultra-thick plates, due to the low total reduction rate, the central part cannot achieve sufficient deformation, so the structure in the central part becomes coarse, thereby increasing the hardenabi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/16C22C38/14C22C38/12C22C38/02C22C38/04C22C38/08B21C37/02
CPCB21C37/02C22C38/02C22C38/04C22C38/08C22C38/12C22C38/14C22C38/16C21D8/0205C21D8/021C21D8/0226C21D8/0247C21D8/0263C21D9/46C21D2201/05C21D2211/002C21D2211/005C21D2211/009C22C38/002C21D6/001C21D6/005C21D6/008
Inventor 李学哲张成豪
Owner 浦项股份有限公司
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