In-situ structure analytical method for nodular cast iron metal material before and after impact fracture

An impact fracture, ductile iron technology, applied in the field of metallography, can solve the problem of no in-situ impact test device and so on

Inactive Publication Date: 2015-03-11
SHENYANG POLYTECHNIC UNIV
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  • Description
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Problems solved by technology

However, for the pendulum Charpy notched impact test, due to the limitation of test conditions, there is currently no in-situ impact test device similar to the in-situ tensile test

Method used

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  • In-situ structure analytical method for nodular cast iron metal material before and after impact fracture
  • In-situ structure analytical method for nodular cast iron metal material before and after impact fracture
  • In-situ structure analytical method for nodular cast iron metal material before and after impact fracture

Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0013] Take QT400-18L ferritic ductile iron as an example:

[0014] The QT400-18L nodular cast iron was used to prepare V-shaped notch impact samples according to the conventional method, and the two sides of the sample containing the V-shaped notches were roughly ground and finely ground, and polished with abrasive paste and corroded by 4% nitric acid alcohol. Observe the sample and select the target microstructure area near the V-shaped notch. An indentation mark was made on the target area using a Vickers microhardness tester with a load of 0.2 kgf. The target area was photographed using a scanning electron microscope. Put the photographed sample into a low-temperature tank, lower it to the required test temperature (take -20°C as an example) with liquid nitrogen, and keep it warm for 15 to 20 minutes, then quickly take out the sample, and place it under the pendulum impact testing machine. A Charpy notched impact test was performed. The fractured impact sample was obser...

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Abstract

The invention belongs to the metallographic field and particularly relates to an observing and analyzing method of researching a micro structure metallograph of nodular cast iron before and after impact fracture at different temperatures. The method comprises the following steps: coarsely grinding, finely grinding, polishing and corroding two side faces of a V-shaped notch of a nodular cast iron impact test sample; observing under a microscope; selecting a classical region near the V-shaped notch; pressing a microhardness indentation at the center of the region as a mark, and photographing and storing; then, carrying out a Charpy notch impact test at different temperatures ranging from 20 DEG C to minus 80 DEG C; finally, combining the microhardness indentation and surrounding graphite nodule morphology features to obtain micro structure photos of a same region before and after impact so as to achieve comparative analysis of detail change of the nodular cast iron structure behind and after impact. The method is an in-situ structure analytical method which is wide in application range, simple to operate and high in reliability.

Description

technical field [0001] The invention belongs to the field of metallography, and in particular relates to a metallographic observation and analysis method for studying the microstructure of ductile iron before and after impact fracture at different temperatures. Background technique [0002] In situ tracking observation can undoubtedly provide direct and high-contrast experimental results for the study of microstructure evolution process. For example, in situ observation using a scanning electron microscope equipped with a stretching stage is an effective method for in situ analysis. However, for the pendulum Charpy notched impact test, due to the limitation of the test conditions, there is no in-situ impact test device similar to the in-situ tensile test. Therefore, in the process of studying impact fracture, an in situ tissue analysis method with wide application range, simple operation and high reliability is needed. Contents of the invention [0003] The invention pro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/06G01N23/22
Inventor 曲迎东张新宁姜珂蒋立鹏尤俊华李荣德
Owner SHENYANG POLYTECHNIC UNIV
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