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Method for displaying original austenite grain boundaries of maraging stainless steel

A technology of austenite grain boundary and display method, which is applied in the preparation of test samples, metal material coating technology, etc., and can solve the problems of difficulty in displaying grain boundaries

Inactive Publication Date: 2015-04-01
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method can solve the difficult problem of displaying the grain boundary of prior austenite in maraging stainless steel, so that the grain boundary can be displayed effectively, clearly and completely without the interference of the structure

Method used

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  • Method for displaying original austenite grain boundaries of maraging stainless steel
  • Method for displaying original austenite grain boundaries of maraging stainless steel
  • Method for displaying original austenite grain boundaries of maraging stainless steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] The photo of aged 17-4PH maraging stainless steel after passivation treatment with 60% nitric acid aqueous solution for 4 minutes and electrolytic etching with 6V voltage for 4 minutes is as follows: figure 1 shown.

[0027] 1. Sample preparation: first cut out the aged sample, and polish one of the planes of the sample on 240#, 600#, 1000#, 2000# metallographic sandpaper from coarse to fine, and then use a particle size of W2. 5 diamond polishing liquid for polishing, polishing to no scratches and then blowing dry. At the same time, in order to prevent the oxide skin on the sample from polluting the electrolyte during the electrolytic etching process, the remaining surfaces only need to be polished with 240# metallographic sandpaper.

[0028] 2. Passivation treatment: Put the polished sample in 60% nitric acid aqueous solution for passivation treatment for 4 minutes;

[0029] 3. Electrolytic etching: The sample that has been passivated in step 2 is subjected to elect...

Embodiment 2

[0031] The photo of the aged 17-4PH maraging stainless steel after passivation treatment with 55% nitric acid aqueous solution for 5 minutes and electrolytic etching with 5V voltage for 5 minutes is as follows: figure 2 shown.

[0032] 1. Sample preparation: same as Example 1.

[0033] 2. Passivation treatment: the passivation solution is 55% nitric acid aqueous solution, and the time is 5 minutes

[0034] 3. Electrolytic etching: the electrolytic etching solution is 55% nitric acid aqueous solution, the voltage is 5V, and the time is 5min. Under the microscope, a clear and complete prior austenite grain boundary without organizational interference can be observed, and the larger black structure is ferrite.

Embodiment 3

[0036] The photo of the aged 17-4PH maraging stainless steel after passivation treatment with 65% nitric acid aqueous solution for 3 minutes and electrolytic etching with 8V voltage for 3 minutes is as follows: image 3 shown.

[0037] 1. Sample preparation: same as Example 1.

[0038] 2. Passivation treatment: the passivation solution is 65% nitric acid aqueous solution, and the time is 3 minutes

[0039] 3. Electrolytic etching: The electrolytic etching solution is 65% nitric acid aqueous solution, the voltage is 8V, and the time is 3 minutes. Under the microscope, a clear and complete prior austenite grain boundary without organizational interference can be observed, and the larger black structure is ferrite.

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Abstract

The invention provides a method for displaying original austenite grain boundaries of maraging stainless steel. The displaying of the original austenite grain boundaries is completed by three steps, namely, preparing a sample, carrying out passivation treatment with concentrated nitric acid and carrying out electrolytic etching with concentrated nitric acid. The method comprises the following steps: firstly preparing the sample, grinding and polishing one surface of the sample and grinding the other surfaces of the sample; placing the polished sample in 55-65% (volume fraction) aqueous nitric acid solution and carrying out passivation treatment for 3-5 minutes; carrying out electrolytic etching on the sample at room temperature for 3-5 minutes by adopting stainless steel sheet as a cathode and the passivated sample as an anode at the electrolytic voltage of 5-8V; after the electrolysis, completely rinsing the sample with tap water, rinsing the sample with alcohol and carrying out blow-drying and then observing the clear and complete microstructure-interference-free original austenite grain boundaries under the microscope. The method has the advantages that after the passivation treatment, the grain boundaries are preferentially displayed as compared with microstructures; no residual etching products are caused; the voltage is relatively low and the etching end point is easy to control.

Description

technical field [0001] The invention belongs to the technical field of metallographic detection, and in particular relates to a method for displaying the original austenite grain boundary of 0Cr17Ni4Cu4Nb maraging stainless steel by using a method of passivation treatment and electrolytic etching. Background technique [0002] Grain size is an important parameter of steel, which directly affects the properties of steel. Therefore, grain boundary display technology is an indispensable work in the process of steel production research. Maraging stainless steel has high strength and corrosion resistance, and has strict requirements on grain size, so the display technology of the original austenite grain boundary of maraging stainless steel is particularly important. [0003] At present, the common etching agents for maraging stainless steel are mainly five kinds of ferric chloride + hydrochloric acid aqueous solution, nitric acid hydrochloric acid aqueous solution, picric acid +...

Claims

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Application Information

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IPC IPC(8): G01N1/32C23C22/50C25F3/06
Inventor 单以银王威谢耀乐胡雪严伟杨柯
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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