SNCrW stainless steel metallographic etching liquid, preparation method thereof and using method thereof

A preparation method and technology of corrosion solution, which is applied in the field of corrosion solution, can solve problems such as poor corrosion reproducibility, poor control of corrosion time, and easy over-corrosion, etc., to achieve clear metallographic structure and grain boundaries, and to meet accurate ratings and well-controlled effects at grain size levels

Inactive Publication Date: 2019-03-15
FUSHUN SPECIAL STEEL SHARES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, in China, 10% oxalic acid solution electrolysis and 1.5 g copper sulfate solution are generally used for corrosion. In foreign countries, 10% oxalic acid solution is used for electrolysis corrosion, and 10% oxalic acid solution is used for electrolysis corrosion. The corrosion time is not easy to control, and the current and voltage are not easy to control. Over-corrosion, the corroded sample is observed under a microscope, there are many corrosion pits, most of the carbide particles are corroded, it is difficult to judge the distribution of carbides, the sample needs to be re-sampled after over-corrosion, and the inspection efficiency is extremely high Low; if the corrosion is wiped with 1.5 grams of copper sulfate solution, the sample has uneven corrosion, and some areas cannot clearly display grains and carbides. The reproducibility of corrosion by this method is not good, which affects the tissue inspection

Method used

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  • SNCrW stainless steel metallographic etching liquid, preparation method thereof and using method thereof
  • SNCrW stainless steel metallographic etching liquid, preparation method thereof and using method thereof
  • SNCrW stainless steel metallographic etching liquid, preparation method thereof and using method thereof

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Experimental program
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Effect test

Embodiment 1、 Embodiment 3 and Embodiment 3

[0037] Implementation 1, embodiment 3 and embodiment 3 use corrosion solution method as follows:

[0038] When using a corrosive solution, first sample the SNCrW (3Cr20Ni10W2) stainless steel after solid solution, and cut it into a metallographic sample of 10mm×20mm×10mm with a cutting machine; Chamfer and grind the inspection surface to avoid scratching the polishing cloth during subsequent polishing; use 320# sandpaper to conduct metallographic rough grinding on the metallographic sample, and then use 800#, 1000#, 1500# metallographic water sandpaper for metallographic test Then use 2.5μm diamond abrasive paste to grind and polish the metallographic sample on the polishing machine. After grinding and polishing for 2 minutes, when it is observed that the polished surface of the metallographic sample is bright without any scratches, replace it with a clean one. Felt polishing cloth, use distilled water as a lubricant, and polish for 1min; rinse the grinding and polishing surfa...

Embodiment 1

[0040] The composition of the corrosion solution: 90mL of water, 15mL of concentrated hydrochloric acid, 5g of ferric sulfate, wherein the concentration of concentrated hydrochloric acid is 36% to 38%, and the water is distilled water;

[0041] When preparing the corrosion solution, first use an electronic balance to weigh 5g of ferric sulfate and put it into a 250mL beaker, then use a measuring cylinder to measure 90mL of water and pour it into the beaker, then measure 15mL of concentrated hydrochloric acid into the beaker, stir with a glass rod until the sulfuric acid After the iron is completely dissolved, let it stand for at least 2 minutes;

[0042] When using corrosive liquid, the metallographic sample corrosion time reaches 5min.

[0043] From figure 1 , figure 2 It can be seen that the SNCrW (3Cr20Ni10W2) stainless steel metallographic corrosion solution has a very good corrosion effect. When it is used to corrode metallographic samples, the structure of the metallo...

Embodiment 2

[0045] The composition of the corrosion solution: 89mL of water, 16mL of concentrated hydrochloric acid, 6g of ferric sulfate, wherein the concentration of concentrated hydrochloric acid is 36% to 38%, and the water is distilled water;

[0046] When preparing the corrosion solution, first weigh 6g of ferric sulfate with an electronic balance and put it into a 250mL beaker, then use a measuring cylinder to measure 89mL of water and pour it into the beaker, then measure 16mL of concentrated hydrochloric acid into the beaker, stir with a glass rod until the sulfuric acid After the iron is completely dissolved, let it stand for at least 2 minutes;

[0047] When using corrosive liquid, the metallographic sample corrosion time reaches 6min.

[0048] From image 3 , Figure 4 It can be seen that the SNCrW (3Cr20Ni10W2) stainless steel metallographic corrosion solution has a very good corrosion effect. When it is used to corrode metallographic samples, the structure of the metallograp...

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Abstract

The invention discloses a SNCrW (3Cr20Ni10W2) stainless steel metallographic etching liquid (hereinafter referred to as an etching liquid), a preparation method thereof and a using method thereof. Theetching liquid comprises the following component and ratio: water: concentrated hydrochloric acid: iron sulfate=89mL-91mL: 14mL-16mL: 4g-6g; the concentration of the concentrated hydrochloric acid is36%-38%; water is distilled water; the preparation method of the etching liquid comprises: pouring, in turn, the iron sulfate weighed with an electronic scale, a small amount of water taken with a measuring cylinder and the concentrated hydrochloric acid taken with a measuring cylinder into a beaker, stirring with a glass rod until the iron sulfate is completely melted and standing for at least 2minutes. When in use, a prepared sample is directly placed in the prepared etching liquid, and the surface subjected to grinding and polishing is completely immersed in the etching liquid, and is etched for 4 min to 6 min. The invention has the following beneficial effects: the inspection efficiency is improved, the metallographic structure of the SNCrW (3Cr20Ni10W2) stainless steel can be quickly and clearly etched; the etching effect is good, carbide particles in the structure are clearly displayed, the metallographic structure and the grain boundary are very clear, and the grain display iscomplete.

Description

technical field [0001] The invention relates to an etching liquid showing a metallographic structure, in particular to a SNCrW (3Cr20Ni10W2) stainless steel metallographic etching liquid and a preparation method and use method thereof. Background technique [0002] SNCrW (3Cr20Ni10W2) is a heat-resistant valve steel containing high carbon, chromium, and tungsten. Tensite grain size and carbide distribution form are the main factors affecting the performance and service life of the steel. SNCrW (3Cr20Ni10W2) steel has a high degree of alloying and contains high-density tungsten. The segregation of tungsten can easily cause carbide segregation, that is, carbide segregation. In the area where carbide accumulates, the austenite grains are covered. The boundary is not easy to display, and metallographic corrosion is more difficult. At present, in China, 10% oxalic acid solution electrolysis and 1.5 g copper sulfate solution are generally used for corrosion. In foreign countries...

Claims

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Application Information

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IPC IPC(8): C23F1/28G01N1/32
CPCC23F1/28G01N1/32
Inventor 刘玉芬牛伟瞿晓刚谷强王学惠谭庆丰杨天亮徐晓慧王宇蔡清曹丽红
Owner FUSHUN SPECIAL STEEL SHARES
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