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Method for determination of brittle crack propagation stopping performance in high-intensity thick steel plate

A technology of brittle crack propagation and determination method, applied in the direction of strength characteristics, testing material strength using a single impact force, instruments, etc., can solve a large number of procedures and time problems, and achieve the effect of simple method, effective quality management, and improved accuracy

Active Publication Date: 2012-05-23
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0012] However, to actually measure the Kca value, a large test piece and a large testing machine are required, and a lot of procedures and time are required until the test results are obtained.

Method used

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  • Method for determination of brittle crack propagation stopping performance in high-intensity thick steel plate
  • Method for determination of brittle crack propagation stopping performance in high-intensity thick steel plate
  • Method for determination of brittle crack propagation stopping performance in high-intensity thick steel plate

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no. 1 Embodiment approach

[0076] Hereinafter, the method for determining the brittle crack propagation stopping performance of the high-strength thick steel plate according to the first embodiment of the present invention will be described based on the drawings.

[0077] The high-strength thick steel plate that is the subject of the determination method of the present embodiment is a steel plate for large-scale ship hulls or water supply iron pipes, and preferably has a thickness of 50 mm or more and a yield strength of 240 to 1000 N / mm 2 . First, for example, 5 to 10 high-strength thick steel plates as standard steels are manufactured with a specific composition and manufacturing method, and the Kca value of the high-strength thick steel plate is obtained by ESSO tests using the methods disclosed in Non-Patent Documents 1 and 2. In addition, small test specimens were taken from the above-mentioned standard steel thick steel plates, and the characteristic values ​​of the small test specimens were obtained ...

no. 2 Embodiment approach

[0141] Hereinafter, the method for determining the brittle crack propagation stopping performance of the high-strength thick steel plate according to the second embodiment of the present invention will be described. The difference between the above-mentioned first embodiment and this embodiment is that in order to determine the brittle crack propagation stopping performance with higher accuracy, internal small test pieces for internal small-scale tests are taken from two regions inside the steel plate. In the method of the second embodiment, the small surface layer test piece is removed from the surface layer in the same manner as in the first embodiment. Figure 2B Taken at the position 12 shown. Internal small test piece from Figure 2B Take both sides of the two parts shown in 9a and 11. As a surface layer miniaturization test, a drop weight impact test was performed in the same manner as in the first embodiment. The V-notch Charpy impact test or the herringbone-notch Charp...

Embodiment 1

[0157] The composition of the steel plate used in this embodiment is shown in Table 1. The main rolling conditions, cooling conditions, heat treatment conditions, plate thickness and yield strength YS of each steel plate are shown in Table 2. From these 70mm thick steel plates Figure 2B The sampling form shown takes a small test piece. Table 3 below shows the type of the small-scale test performed on each steel sample and the location of the small-scale test piece.

[0158] Table 1

[0159]

[0160] Table 2

[0161]

[0162] The result of the V-notch Charpy impact test is expressed by a temperature called the fracture shape transition temperature, which represents a 50% brittle fracture rate: vTrs. The result of the herringbone-notch Charpy impact test is expressed by the transition temperature that can ensure the absorbed energy of 70J. The result of the sharp-notch Charpy impact test is expressed by a transition temperature that can ensure an absorbed energy of 40 J.

[0163] N...

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Abstract

Disclosed is a method for determining the brittle crack propagation stopping performance of a high-intensity thick steel plate, comprising: a step of performing a large test and a compound small test using standard steel; a step of calculating a correlation model between the results of the large test and the results of the compound small test using the standard steel; a step of performing the compound small test using sample steel; and a step of estimating the brittle crack propagation stopping performance of the sample steel by substituting the results of the compound small test using the sample steel into the correlation model, wherein the compound small test includes (a) a step of obtaining a surface layer small test piece which includes a portion of the steel plate surface layer; (b) a step of obtaining an inner small test piece respectively from one or no less than two inner regions which do not include the portion of the steel surface layer; (c) a step of performing a drop weight test using the surface layer small test piece; and (d) a step of performing a small test for measuring the percent brittle fracture or the absorption energy using the inner small test piece; and thecompound small test is performed in different fashions for the surface layer small test piece and the inner small test piece respectively.

Description

Technical field [0001] The present invention relates to inferring the brittle crack propagation stopping performance of high-strength thick steel plates used in the construction of structural parts that need to prevent large-scale damage and damage caused by the propagation of brittle cracks through a simple and reasonable method, and inspecting high-strength thick steel plates. The performance method of the steel plate. [0002] This application is based on the Patent Application No. 2010-048417 filed in Japan on March 4, 2010 and claims the priority, and the content is quoted here. Background technique [0003] A container ship or bulk carrier as a welded structure is different from an oil tanker in that there are few partitions in the cabin and a large opening in the upper part of the ship. On the contrary, an oil tanker is a structure in which the interior is subdivided by an oil tank, and the inner wall or upper deck also bears the strength of the hull. [0004] Therefore, in ...

Claims

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Application Information

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IPC IPC(8): G01N3/30C21D8/02C22C38/00C22C38/06C22C38/60
CPCC21D8/02C22C38/14G01N2203/0246C22C38/04G01N2203/0066C22C38/12G01N3/303C22C38/02C22C38/06G01N2203/0218C21D1/55C22C38/08C22C38/16
Inventor 石川忠井上健裕中岛清孝白幡浩幸大谷润伊藤昭
Owner NIPPON STEEL CORP
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