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Method for judging plasticity index of material in rapid deformation process through drop-weight tear test (DWTT)

A plastic index, fast technology, applied in the field of mechanical processing, to achieve the effect of easy use and low implementation cost

Inactive Publication Date: 2015-12-23
BEIJING LONGSHINE OIL TUBULAR TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to provide a kind of method that adopts DWTT test to judge the plasticity index when material obtains rapid deformation, thus solves the aforementioned problems existing in the prior art

Method used

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  • Method for judging plasticity index of material in rapid deformation process through drop-weight tear test (DWTT)
  • Method for judging plasticity index of material in rapid deformation process through drop-weight tear test (DWTT)

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Embodiment

[0029] The method described in this embodiment adopts the DWTT test to evaluate the material to obtain the method of plastic index when rapidly deforming, and the method is realized according to the following steps:

[0030] S1, first obtain the original thickness t of the sample to be subjected to the DWTT test 0 , according to the formula (1) to calculate from the notch root of the sample to the hammering edge minus a sample wall thickness t 0 The original area S of the assessment area 0 ;

[0031] S 0 = t 0 ×(71-t 0 )(1);

[0032] S2, conduct the DWTT test, measure and record the minimum thickness t of the specimen fracture min and the maximum fracture thickness t max , and the envelope area S of the fracture contour in the assessment area;

[0033] S3, calculating the plasticity index of the sample during rapid deformation; the plasticity index includes: narrowing rate τ, widening rate β, deformation rate λ and area reduction rate δ.

[0034] Calculate the narrowi...

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Abstract

The invention discloses a method for judging the plasticity index of a material in the rapid deformation process through a drop-weight tear test (DWTT). The method includes the following steps that S1, the original thickness t0 of a sample to be subjected to the DWTT is acquired first, and the original area S0 of a judgment region which ranges from the root portion of a sample notch to a hammering edge by subtracting the wall thickness t0 of the sample is calculated; S2, the DWTT is carried out, the minimum thickness tmin and the maximum thickness tmax of a fracture of the sample are measured and recorded, and the enveloping area S of the fracture contour line in the region is judged; S3, the plasticity index of the sample in the rapid deformation process is calculated. By the adoption of the method, the problem about how to judge the plasticity index when the material is loaded and cracked at a high speed is solved, and the basis is provided for crack-stopping study of a petroleum and gas pipeline. According to the method, the DWTT method is adopted, the plasticity index of the material in the rapid deformation process is acquired by judging the fracture of the tested sample. The method is convenient to use, and implementation cost is low.

Description

technical field [0001] The invention relates to the technical field of mechanical processing, in particular to a method for evaluating the plasticity index of a material during rapid deformation by using a DWTT experiment. Background technique [0002] In the process of natural gas pipeline transportation, due to the compressibility of gas, once the natural gas pipeline cracks, the pressure in the pipeline cannot be completely released instantly, and there is a problem of whether the crack can be stopped after the crack is opened. For traditional lower steel grades (up to X70 in APISPEC5L), the Charpy impact energy value determined by Battele hyperbolic prediction is more accurate. However, when the higher steel grades (such as X80 or higher in APISPEC5L) use the Battele hyperbola to predict the Charpy impact energy value of crack arrest, its accuracy decreases. The reason for this problem can be considered to be that when the steel grade is low, because the low steel grade...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/303
Inventor 李记科杨红兵何小东王高峰聂向晖李富强马飞
Owner BEIJING LONGSHINE OIL TUBULAR TECH
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