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A kind of etchant for inspecting dissimilar steel welded joint structure and using method thereof

A technology of welding joints and etchant, applied in the preparation of test samples, etc., can solve the problems of complex display methods, large potential differences in different regions, and corrosion artifacts, so as to achieve real and stable erosion effects, good reproducibility, Easy to prepare effects

Active Publication Date: 2019-10-25
DONGFANG BOILER GROUP OF DONGFANG ELECTRIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] (1) The chemical composition of each area of ​​the joint is very different;
[0005] (2) There are large differences in the tissue types of the joints in each region;
[0006] (3) The size of the composition transition zone in the joint is often small, and the potential difference between different regions is large
[0007] These factors make the electrochemical properties of dissimilar steel joints different in different regions, and the display method becomes more complicated and difficult compared with the same steel. sex clearly
The current practice is usually to use a variety of etchant to etch in stages to display the structure and morphology of each area of ​​the joint respectively, but there are problems such as corrosion film interference, over-corrosion, corrosion surface pollution, and corrosion artifacts caused by multiple corrosions. and other disadvantages, which greatly hinder the observation and analysis of the metallographic structure of dissimilar steel joints, and affect the quality of inspection

Method used

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  • A kind of etchant for inspecting dissimilar steel welded joint structure and using method thereof
  • A kind of etchant for inspecting dissimilar steel welded joint structure and using method thereof
  • A kind of etchant for inspecting dissimilar steel welded joint structure and using method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0050] refer to Figure 1-5 shown, where image 3 , 4 The left area in the middle is the heat-affected zone, and the right area is the weld area. Through ferric chloride-sodium chloride-nitric acid-phosphoric acid solution etching agent, through one-time corrosion, the structure and morphology of each area of ​​SA-213T92 and TP310HCbN heat-resistant stainless steel welded joints can be displayed clearly, completely and without artifacts at the same time , so as to accurately carry out the metallographic inspection of the joint. The inventive method is simple, convenient, fast and safe to operate, the etchant can be placed for a long time, the display effect is stable, and the reproducibility is good, mainly including the following contents:

[0051] 1. Etchant mass percentage content composition:

[0052] (1) 1% ferric chloride (analytical pure);

[0053] (2) 1% sodium chloride (analytical pure)

[0054] (3) 26% concentrated nitric acid (analytical pure);

[0055] (3) 7...

Embodiment 2

[0062] refer to Figure 6-10 shown, where Figure 8 , 9 The left area in the middle is the weld area, and the right area is the heat-affected zone. This example is basically the same as Example 1, the difference is that the etchant is used to inspect the welded joints of SA-213T91 and S30432 heat-resistant stainless steel dissimilar steel, and the mass percentage content of the etchant is composed of:

[0063] (1) 2% ferric chloride (analytical pure);

[0064] (2) 3% sodium chloride (analytical pure)

[0065] (3) 15% concentrated nitric acid (analytical pure);

[0066] (3) 80% phosphoric acid (analytical pure).

Embodiment 3

[0068] refer to Figure 11-15 shown, where Figure 13 , 14 The left area in the middle is the heat-affected zone, and the right area is the weld area. This example is basically the same as Example 1, the difference is that the etchant is used to inspect the structure of the welded joint between SA-213T91 and TP347HFG heat-resistant stainless steel dissimilar steel, and the mass percentage content of the etchant is composed of:

[0069] (1) 5% ferric chloride (analytical pure);

[0070] (2) 6% sodium chloride (analytical pure)

[0071] (3) 12% concentrated nitric acid (analytical pure);

[0072] (3) 77% phosphoric acid (analytical pure).

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Abstract

The invention discloses an etching agent for inspecting a dissimilar steel welding joint structure and a using method thereof. The etching agent comprises the following components, by mass, of 1%-8% of ferric chloride, 1%-9% of sodium chloride, 8%-30% of concentrated nitric acid and 53%-90% of phosphoric acid. The use method of the etching agent sequentially comprises the following steps that according to the proportion, the reagents are weighed correspondingly and are uniformly stirred; the etching agent is dipped to wipe the polishing surface of a sample, when the polishing surface becomes gray, the sample is washed out and dried; the etched sample is placed under light field lighting of an optical microscope to be observed. According to the etching agent and the using method thereof, reagent composition is simple and safe, and the long-term stable effective effect is achieved; and through one-time etching, microscopic structure morphologies of all areas of T91 / 92 and the austenitic heat-resistant stainless steel welding joint can be simultaneously, clearly and truly displayed without false appearance, the structure details are completely displayed, and observation equipment is simple and does not have special requirements.

Description

technical field [0001] The invention belongs to the field of etchant for testing the welded joint structure of T91 / 92 and austenitic heat-resistant stainless steel dissimilar steel. Background technique [0002] With the improvement of thermal power generation unit parameters, different temperature zones use different grades of materials, which not only meets the use requirements in design, but also reduces manufacturing costs, which has obvious economic benefits. Therefore, in the current high-grade boiler manufacturing process, T91 / 92 is often welded with austenitic heat-resistant stainless steel such as S30432, TP347H / HFG, TP310HCbN, and is used in the manufacture of boiler high-temperature superheater and reheater components. The welding of dissimilar steels is more complicated and difficult than that of the same kind of steels, and the quality of its welded joints has always been the focus of attention of boiler manufacturers and power plants. The metallographic struct...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N1/32
CPCC23F1/28G01N1/32
Inventor 江平曾辉李健董猛夏彩荥赵彦郭宏川曾凡伟
Owner DONGFANG BOILER GROUP OF DONGFANG ELECTRIC CORP