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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 judgment method, which is applied in the direction of strength characteristics, testing material strength with one-time impact force, instruments, etc., can solve a lot of procedures and time problems, and achieve the effect of simple method, effective quality management, and improved accuracy

Active Publication Date: 2013-07-17
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, a method of judging 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 with reference to the drawings.

[0077] The high-strength thick steel plate to be targeted by the determination method of this embodiment is a steel plate for large ship hulls or iron water supply pipes, preferably with a plate 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 steel are produced with a specific composition and production method, and the Kca value of the high-strength thick steel plate is obtained by the ESSO test using the method disclosed in Non-Patent Documents 1 and 2. In addition, small test pieces were taken from thick steel plates of the above-mentioned standard steel, and the characteristic values ​​of the small test pieces were obtained by performing vari...

no. 2 Embodiment approach

[0141] Hereinafter, a method of judging 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 internal small-scale test pieces for the internal small-scale test are collected from two regions inside the steel plate in order to judge the brittle crack propagation stopping performance with higher accuracy. In the method of this second embodiment, the surface layer small test piece is obtained from Figure 2B Position 12 shown is taken. Internal small test piece from Figure 2B Both sides of the two sites shown in 9a and 11 are taken. As a small surface layer 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 Charpy impact test is performed using the internal small-scale test of tw...

Embodiment 1

[0157]The composition of steel plates used in this example 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 thick steel plates with a plate thickness of 70 mm Figure 2B In the shown collection form, a small test piece was taken. Table 3 described later shows the types of small-scale tests performed on the steel samples and the locations where the small-scale test pieces were collected.

[0158] Table 1

[0159]

[0160] Table 2

[0161]

[0162] The results of the V-notch Charpy impact test are represented by a temperature representing a 50% brittle fracture rate called a fracture shape transition temperature: vTrs. The results of the chevron notch Charpy impact test are shown by the transition temperature at which absorbed energy of 70J can be ensured. The results of the sharp notch Charpy impact test are shown by the transitio...

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Abstract

A method of determining brittle crack propagation arrestability of a high-strength steel plate includes the steps of: performing a large-scale test and a composite small-scale test using standard steel; calculating a correlation model of the result of the large-scale test and the result of the composite small-scale test using the standard steel; performing the composite small-scale test using a steel specimen; and estimating the brittle crack propagation arrestability of the steel specimen by substituting the result of the composite small-scale test using the steel specimen into the correlation model. The composite small-scale test includes the sub steps of: (a) sampling a surface-small-scale-test-piece including a surface part of a steel plate; (b) sampling inner-small-scale-test-pieces from one or more inner regions not including the surface part of the steel plate; (c) performing a drop weight test using the surface-small-scale-test-piece; and (d) performing a small-scale test of measuring a brittle fracture percentage or absorbed energy using the inner-small-scale-test-pieces. The composite small-scale test includes performing the small-scale test on the surface-small-scale-test-piece and the inner-small-scale-test-pieces through the use of different methods.

Description

technical field [0001] The present invention relates to checking the brittle crack propagation stop 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 brittle crack propagation by a simple and rational method, and to examine the Methods for properties of steel plates. [0002] This application is based on and claims priority to Patent Application No. 2010-048417 for which it applied in Japan on March 4, 2010, and uses the content here. Background technique [0003] Unlike oil tankers, container ships and bulk carriers, which are welded structures, have fewer partitions in the cabin and a larger opening on the upper part of the ship. On the contrary, an oil tanker has a structure in which the interior is subdivided by oil tanks, and the interior wall or upper deck also bears the strength of the hull. [0004] Therefore, in container ships, in order to ensure the strength o...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N3/30C21D8/02C22C38/00C22C38/06C22C38/60
CPCG01N2203/0246G01N3/303C22C38/14C22C38/12C22C38/02C21D1/55C22C38/08G01N2203/0218C22C38/16C22C38/04C22C38/06G01N2203/0066C21D8/02
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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