Method for displaying original austenite grains of pipeline steel with strength grade of X70 and above

A technology of austenite grains and pipeline steel, which is applied in the display field of austenite grains, can solve the problems of difficulty in displaying the original austenite grains of pipeline steel, and achieve clear display and simple operation

Inactive Publication Date: 2010-07-28
BEIJING LONGSHINE OIL TUBULAR TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] The purpose of the present invention is to provide a simple, economical and safe method for clearly displaying the original austenite grains of pipeline steel, solve the problem of dif

Method used

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  • Method for displaying original austenite grains of pipeline steel with strength grade of X70 and above
  • Method for displaying original austenite grains of pipeline steel with strength grade of X70 and above
  • Method for displaying original austenite grains of pipeline steel with strength grade of X70 and above

Examples

Experimental program
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Effect test

Embodiment 1

[0026] Example 1: Determination of the prior austenite grain size of a certain X70 pipeline steel

[0027] The technological process and steps of the present embodiment are as follows:

[0028] a Heat treatment: Process the material into a 15mm×15mm×20mm sample, place it in a box-type resistance furnace heated to 950°C, keep it warm for 0.5h, put it in NaCl aqueous solution for quenching, and take it out after it is completely cooled.

[0029] b Grinding and polishing: take the quenched sample to a grinder for preliminary grinding, after the rough ground sample is rinsed with clean water, then put the grinding surface on the metallographic sandpaper of each number from coarse to fine Perform fine sanding. Each time the next finer sandpaper is changed, the sample should be rotated 90° for grinding. Finally, the ground sample was cleaned and polished on a polishing machine until the polished surface was bright and traceless. The polishing agent is 1.5μm diamond polishing past...

Embodiment 2

[0038] Example 2: Determination of the grain size of prior austenite in a certain X100 pipeline steel

[0039] a Heat treatment: Process the material into a 15mm×15mm×20mm sample, place it in a box-type resistance furnace heated to 950°C, keep it warm for 1 hour, put it in NaCl aqueous solution for quenching, and take it out after it is completely cooled.

[0040] b Grinding and polishing: take the quenched sample to a grinder for preliminary grinding, after the rough ground sample is rinsed with clean water, then put the grinding surface on the metallographic sandpaper of each number from coarse to fine Perform fine sanding. Each time the next finer sandpaper is changed, the sample should be rotated 90° for grinding. Finally, the ground sample was cleaned and polished on a polishing machine until the polished surface was bright and traceless. The polishing agent is 1.5μm diamond polishing paste, and water is used as lubricant.

[0041] c Corrosion: Put the beaker containin...

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Abstract

The invention discloses a method for displaying original austenite grains of pipeline steel with strength grade of X70 and above, and belongs to the technical field of metallographic structure observation. The method comprises the following steps: firstly, performing heat treatment and quenching on a sample at the temperature of 950 DEG C to obtain a single austenite structure; secondly, grinding and polishing the obtained austenite structure; and thirdly, corroding the ground and polished austenite structure in etching solution, wherein the etching solution is mixed liquor of supersaturated picric acid, Eagle high-efficiency detergent and 2 percent nitric acid, so that the austenite structure can be showed and can be clearly observed under a microscope. The method for displaying the original austenite grains of the pipeline steel with the strength grade of X70 and above solves the display problem of the original austenite grains of the pipeline steel with high-strength grade. The method has the advantages of capability of clearly displaying the original austenite grains of the pipeline steel with the strength grade of X70 and above, economic and safe etchant formula and simple test process operation.

Description

technical field [0001] The invention relates to the display field of austenite grains, in particular to a method for displaying the original austenite grains of pipeline steel with strength grade X70 and above. Background technique [0002] The size and uniformity of prior austenite grains in steel have a great influence on its microstructure and properties after phase transformation, thus directly affecting the mechanical and process properties of the material. With the help of austenite grain display, it is possible to study the structural changes of pipeline steel in controlled rolling and controlled cooling, which is very important for reasonable control of process parameters and ensuring product performance; in addition, it can also be used to study the grain growth law of pipeline steel during heating , which is of great help to the design of the heat treatment process of pipe fittings, so it is of great significance to accurately display the original austenite grains ...

Claims

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Application Information

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IPC IPC(8): G01N1/44G01N1/28G01N1/32
Inventor 杜伟李云龙杨专钊李记科张鸿博王长安娄琦黄磊
Owner BEIJING LONGSHINE OIL TUBULAR TECH
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