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Method for clearly displaying low carbon low alloy steel austenite crystal

A technology for austenite grains and low alloy steels, applied in the metallographic structure display method, can clearly display the field of austenite grains of low carbon steel and low alloy steel, and can solve the problem that the austenite grain boundary cannot be displayed and the austenite grain boundary is difficult Display, unable to display austenite grain boundaries and other problems, to achieve the effect of ensuring product quality and reasonable control of process parameters

Inactive Publication Date: 2009-01-21
NORTH CHINA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This etchant is very effective for medium and high-carbon steels, but for low-carbon low-alloy high-purity steels, the problem that the austenite grain boundaries are difficult to display has not been well resolved.
However, the above-mentioned corrosion method is limited to the corrosion of steel with specific composition, and the original austenite grain boundary cannot be completely and clearly displayed, especially for the austenite grain boundary of high-purity steel with extremely low carbon content and low impurity content. basically do not show up

Method used

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  • Method for clearly displaying low carbon low alloy steel austenite crystal
  • Method for clearly displaying low carbon low alloy steel austenite crystal
  • Method for clearly displaying low carbon low alloy steel austenite crystal

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] Example 1: The chemical composition of sample 1 is C: 0.08%, Si: 0.24%, Mn: 1.36%, V: 0.035%, Ti: 0.023%, Nb: 0.030%, Als: 0.032%, P: 0.012% , S: 0.003%. Sample quenching: heat the sample to 1050°C, keep it warm for a certain period of time, let the carbides dissolve in the matrix, and then quench the sample in water with a temperature lower than 20°C; grind and polish the quenched sample; The following ratio is used to configure the etchant: CrO 3 9g, NaOH 40g, picric acid 1.6g, ethylene oxide 2ml, distilled water 80ml. When preparing, first measure 80ml of distilled water and put it in a container, then add CrO to the distilled water 3 , to be CrO 3 Add NaOH after complete dissolution. Since the amount of NaOH is large and it will produce a strong exothermic reaction, it should be added slowly to avoid splashing. After adding NaOH, add picric acid solution and ethylene oxide. The prepared etchant solution was heated to 110°C and kept warm on a constant temperatu...

Embodiment 2

[0017] Example 2: The chemical composition of sample 2 is C: 0.05%, Si: 0.20%, Mn: 1.45%, Mo: 0.17%, Ti: 0.017%, Nb: 0.042%, Als: 0.030%, P: 0.010% , S: 0.005%. Sample quenching: heat the sample to 1150°C, keep it warm for a certain period of time, let the carbides dissolve in the matrix, and then quench the sample in water with a temperature lower than 20°C; grind and polish the quenched sample; The following ratio is used to configure the etchant: CrO 3 10g, NaOH 50g, picric acid 1.8g, ethylene oxide 3ml, distilled water 90ml. Preparation method is with embodiment 1. Heat the prepared etchant solution to 120°C and keep it warm on a constant temperature heating furnace, then put the polished sample into the solution for etching, with the etched side of the sample facing up, and the etching time is 50 minutes. When the polished surface of the sample turns iron blue, take it out, wash it and dry it, and then observe the austenite grains under the microscope. Depend on fi...

Embodiment 3

[0018] Example 3: The chemical composition of sample 3 is C: 0.03%, Si: 0.20%, Mn: 1.72%, Mo: 0.25%, Ti: 0.015%, Nb: 0.040%, V: 0.050%, Cu: 0.2% , Als: 0.025%, P: 0.014%, S: 0.004%. Sample quenching: heat the sample to 1200°C, keep it warm for a certain period of time, let the carbides dissolve in the matrix, and then quench the sample in water with a temperature lower than 20°C; grind and polish the quenched sample; The following ratio is used to configure the etchant: CrO 3 8g, NaOH 45g, picric acid 2g, ethylene oxide 4ml, distilled water 100ml. Preparation method is with embodiment 1. Heat the prepared solution to 130°C and keep it warm on a constant temperature heating furnace, then put the polished sample into the solution for etching, with the etched side of the sample facing up, and the etching time is about 60 minutes. When the polished surface of the sample turns iron blue, take it out, wash it and dry it, and then observe the austenite grains under the microscope...

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Abstract

The invention relates to a method for clearly displaying lower carbon and low alloy steel austenite crystal, which belongs to the technical field of physical detection. The method is used to solve the problem that lower carbon and low alloy steel can not clearly display the austenite crystal thereof. The method comprises a quenching process and a corrosion process, which is characterized in that the proportion of corrosive agent in the process of corroding is that CrO3 8g-10g, NaOH 40g-50g, picric acid 1.6g-2g, epoxyethane 2ml-4ml and distilled water 80ml-100ml. The method adopts specific corrosive agent and is matched with a correct corrosion method, which can clearly display austenite grain boundary. The method fills a gap of low carbon alloy steel austenite grain boundary display technology, which provides an important theoretical basis for a manufacturing enterprise to research the influence of technological parameters to microstructure evolution when the steel is deforming, and plays an important function for producing low carbon alloy steel, reasonably controlling technological parameters and guaranteeing the property of products.

Description

technical field [0001] The invention relates to a metallographic structure display method, in particular to a method for clearly displaying austenite grains of low-carbon steel and low-alloy steel, and belongs to the technical field of physical detection. technical background [0002] The austenite grain size of steel has a great influence on the strength, toughness and fatigue performance of steel, and plays an important role in studying the evolution law of material structure in the process of steel production, reasonably controlling process parameters and ensuring product performance. Therefore, austenite The detection of bulk grain size is of great significance, and its display method has been continuously discussed, innovated and improved by the majority of industry insiders. Whether the austenite grains can be clearly displayed depends on various factors such as the chemical composition of the sample, the heat treatment state, the etching time, the etching method, and ...

Claims

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Application Information

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IPC IPC(8): G01N1/32
Inventor 冯运莉臧振东宋海武孙静
Owner NORTH CHINA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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