A striper for structural steel and a method of striper corrosion

Abstract

The present application relates to a kind of for structural steel's etching corrosion agent and etching corrosion method, specifically relates to the field of etching inspection, the etching corrosion agent includes by mass percentage: inorganic acid 10-12%, reducing organic acid 3-5%, nitrophenol 1-2%, chlorinated high iron 1-5%, the rest is water.This etching corrosion agent provided by the present application, by optimizing the proportion of corrosion agent, reduce the amount of inorganic acid, while introducing other auxiliary reagents, ensure that efficient etching can be realized to etching, while avoiding the appearance of line-shaped corrosion marks, significantly improve the accuracy of etching detection analysis.

Description

Technical Field

[0001] This invention relates to the field of hairline crack inspection, and specifically to a hairline crack etchant and hairline crack etching method for structural steel. Background Technology

[0002] Currently, during the steel product testing process, due to internal defects such as inclusions, bubbles, porosity, or shrinkage cavities in the steel products, fine longitudinal cracks will be generated during the tower test. These cracks will mostly appear after low-magnification pickling.

[0003] However, when performing hairline corrosion using the tower-shaped acid etching method for inspecting non-metallic inclusions in steel according to GB / T 15711-2018, linear corrosion marks are found to appear, which are not true hairline defects and can lead to errors in the detection. Summary of the Invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a hairline etching agent and a hairline etching method for structural steel, so as to solve the defect that linear corrosion marks appear when hairline etching is performed according to the tower-shaped hairline etching method for inspecting non-metallic inclusions in steel according to GB / T 15711-2018, which leads to detection errors.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a hairline etching agent for structural steel, said hairline etching agent comprising, by weight percentage:

[0007] Inorganic acid 10-12%, reducing organic acid 3-5%, nitrophenol 1-2%, ferric chloride 1-5%, balance water.

[0008] The hairline etching agent provided by this invention optimizes the formulation of the etching agent, reduces the amount of inorganic acid, and introduces other auxiliary reagents to ensure efficient etching of hairlines while avoiding linear etching marks, thus significantly improving the accuracy of hairline detection and analysis.

[0009] As a preferred embodiment of the present invention, the inorganic acid includes hydrochloric acid and / or sulfuric acid.

[0010] As a preferred technical solution of the present invention, the reducing organic acid includes one or a combination of at least two of formic acid, oxalic acid, citric acid, tartaric acid, or glycolic acid.

[0011] As a preferred embodiment of the present invention, the nitrophenol comprises p-nitrophenol and / or trinitrophenol.

[0012] In a second aspect, the present invention provides a hairline etching method for structural steel, the hairline etching method comprising: etching a structural steel sample with a hairline etching agent as described in the first aspect.

[0013] As a preferred embodiment of the present invention, the corrosion temperature is 70-90℃.

[0014] As a preferred embodiment of the present invention, the corrosion time is 5-30 minutes.

[0015] As a preferred embodiment of the present invention, the corrosion is supplemented by ultrasound.

[0016] As a preferred embodiment of the present invention, the frequency of the ultrasound is 30-50kHz.

[0017] As a preferred embodiment of the present invention, the power density of the ultrasound is 0.05-0.15 W / cm². 2 .

[0018] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0019] (1) When the hairline etching agent of the present invention is used for hairline detection and analysis, the synergistic effect between the components in the etching agent is utilized to stabilize the etching rate within a controllable range. It will not cause the fine hairline to become invisible due to under-etching, nor will it cause the hairline to widen, melt, or dissolve due to over-etching. The analysis results are basically consistent with the magnetic particle inspection method.

[0020] (2) The etching method of the present invention introduces ultrasonic treatment and hairline etching agent in combination during the process, which can further enhance the accuracy of hairline etching. The analysis results are consistent with the magnetic particle inspection method and have good detection accuracy. This is because ultrasonic vibration can tear the interface between the inclusion and the iron matrix, assist the acid liquid in directional etching of the inclusion phase, completely restore the original extension morphology of the hairline, and form a selective gradient of strong hairline etching and weak matrix etching. This reduces background interference from the source and avoids the discontinuous hairline and incomplete development caused by inclusion residue under static etching.

[0021] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0022] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0023] Currently, during steel product testing, internal defects such as inclusions, bubbles, porosity, or shrinkage cavities can cause fine longitudinal cracks during tower etching tests. These cracks often only become visible after low-magnification pickling. However, when using the tower etching method for hairline etching according to GB / T 15711-2018 (Inspection of Non-metallic Inclusions in Steel), linear corrosion marks are observed, which are not true hairline defects and can lead to testing errors. Therefore, this invention optimizes the etching reagent to ensure efficient etching and visualization of hairline defects while avoiding linear corrosion marks. Specifically:

[0024] I. This embodiment provides a hairline etching agent for structural steel, wherein the hairline etching agent comprises, by weight percentage:

[0025] Inorganic acid 10-12%, reducing organic acid 3-5%, nitrophenol 1-2%, ferric chloride 1-5%, balance water.

[0026] In this invention, structural steel refers to steel that meets specific strength and formability grades. Formability is characterized by elongation after tensile testing. It is mainly used for manufacturing load-bearing structural components, such as 35MnBM, 40MnBH, 45BM, 40CrBM, etc.

[0027] In this invention, the inorganic acid, reducing organic acid, nitrophenol, and ferric chloride in the hairline etching agent refer to the mass concentration of the corresponding molecules, rather than the mass percentage of the aqueous solution of the corresponding substances in the hairline etching agent.

[0028] In this invention, the inorganic acid in the hairline etching agent is 10-12% by mass percentage, for example, it can be 10%, 10.2%, 10.4%, 10.6%, 10.8%, 11%, 11.2%, 11.4%, 11.6%, 11.8% or 12%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0029] In this invention, the reducing organic acid in the hairline etching agent is 3-5% by mass percentage, for example, it can be 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8% or 5%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0030] In this invention, the nitrophenol in the hairline etching agent is 1-2% by mass percentage, for example, it can be 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9% or 2%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0031] In this invention, the ferric chloride in the hairline etching agent is 1-5% by mass percentage, for example, it can be 1%, 1.4%, 1.8%, 2.2%, 2.6%, 3%, 3.4%, 3.8%, 4.2%, 4.6% or 5%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0032] The inorganic acids include hydrochloric acid and / or sulfuric acid.

[0033] The reducing organic acid includes one or a combination of at least two of formic acid, oxalic acid, citric acid, tartaric acid, or glycolic acid.

[0034] The nitrophenol includes p-nitrophenol and / or trinitrophenol.

[0035] In this invention, ferric chloride refers to FeCl3.

[0036] II. This embodiment provides a hairline etching method for structural steel, the hairline etching method comprising: etching a structural steel sample with the hairline etching agent.

[0037] The corrosion temperature is 70-90℃, for example, it can be 70℃, 72℃, 74℃, 76℃, 78℃, 80℃, 82℃, 84℃, 86℃, 88℃ or 90℃, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0038] The corrosion time is 5-30 min, for example, it can be 5 min, 7.5 min, 10 min, 12.5 min, 15 min, 17.5 min, 20 min, 22.5 min, 25 min, 27.5 min or 30 min, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0039] The corrosion process is aided by ultrasound.

[0040] The frequency of the ultrasound is 30-50kHz, for example, it can be 30kHz, 32kHz, 34kHz, 36kHz, 38kHz, 40kHz, 42kHz, 44kHz, 46kHz, 48kHz or 50kHz, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0041] The power density of the ultrasound is 0.05-0.15 W / cm². 2 For example, it could be 0.05 W / cm 2 0.06W / cm 2 0.07W / cm 2 0.08W / cm 2 0.09W / cm 2 0.1W / cm 2 0.11W / cm 2 0.12W / cm 2 0.13W / cm 2 0.14W / cm 2 Or 0.15W / cm 2 The values ​​may include, but are not limited to, the listed values; other unlisted values ​​within this range also meet the requirements.

[0042] In this invention, during the etching process, the etching can be selectively performed on a localized area of ​​the hairline crack. Then, the extended portion of the hairline crack can be subjected to metallographic microscopy and scanning electron microscopy to perform qualitative analysis on the cause of the crack, thereby achieving rapid and accurate determination of the nature of the defect.

[0043] III. To illustrate the corrosion effect achievable by the hairline etching agent provided by this invention, the following example is used for explanation:

[0044] Example 1

[0045] This embodiment provides a hairline etching agent for structural steel and its application, wherein the hairline etching agent comprises, by weight percentage:

[0046] Inorganic acid 11%, reducing organic acid 4%, nitrophenol 1.5%, ferric chloride 3%, balance water;

[0047] The inorganic acid is hydrochloric acid;

[0048] The reducing organic acid is oxalic acid;

[0049] The nitrophenol is trinitrophenol.

[0050] The application process is as follows:

[0051] The structural steel sample (35MnBM) was etched using a hairline etchant;

[0052] The corrosion temperature is 80℃; the corrosion time is 20 minutes.

[0053] Example 2

[0054] This embodiment provides a hairline etching agent for structural steel and its application, wherein the hairline etching agent comprises, by weight percentage:

[0055] Inorganic acid 10%, reducing organic acid 5%, nitrophenol 2%, ferric chloride 1%, balance water;

[0056] The inorganic acid is sulfuric acid;

[0057] The reducing organic acid is citric acid;

[0058] The nitrophenol is p-nitrophenol.

[0059] The application process is as follows:

[0060] The structural steel sample (40MnBH) was etched using a hairline etchant.

[0061] The corrosion temperature is 70℃; the corrosion time is 30 minutes.

[0062] The corrosion process is aided by ultrasound; the frequency of the ultrasound is 30 kHz; the power density of the ultrasound is 0.15 W / cm³. 2 .

[0063] Example 3

[0064] This embodiment provides a hairline etching agent for structural steel and its application, wherein the hairline etching agent comprises, by weight percentage:

[0065] Inorganic acid 12%, reducing organic acid 3%, nitrophenol 1%, ferric chloride 5%, balance water;

[0066] The inorganic acid is hydrochloric acid;

[0067] The reducing organic acid is glycolic acid;

[0068] The nitrophenol is trinitrophenol.

[0069] The application process is as follows:

[0070] The structural steel sample (45BM) was etched using a hairline etchant;

[0071] The corrosion temperature is 90℃; the corrosion time is 5 minutes.

[0072] The corrosion process is aided by ultrasound; the frequency of the ultrasound is 50 kHz; the power density of the ultrasound is 0.05 W / cm³. 2 .

[0073] Example 4

[0074] The only difference from Example 1 is that: the corrosion is supplemented by ultrasound; the frequency of the ultrasound is 40 kHz; and the power density of the ultrasound is 0.1 W / cm². 2 .

[0075] Example 5

[0076] The only difference from Example 1 is that the inorganic acid in the hairline etching agent is 5% by mass.

[0077] Example 6

[0078] The only difference from Example 1 is that the inorganic acid in the hairline etching agent is 18% by mass.

[0079] Example 7

[0080] The only difference from Example 1 is that the reducing organic acid in the hairline etching agent is 1% by mass.

[0081] Example 8

[0082] The only difference from Example 1 is that the reducing organic acid in the hairline etching agent is 8% by mass.

[0083] Example 9

[0084] The only difference from Example 1 is that the nitrophenol in the hairline etching agent is 0.1% by mass.

[0085] Example 10

[0086] The only difference from Example 1 is that the nitrophenol in the hairline etching agent is 5% by mass.

[0087] Example 11

[0088] The only difference from Example 1 is that the ferric chloride in the hairline etchant is 0.1% by mass.

[0089] Example 12

[0090] The only difference from Example 1 is that the ferric chloride in the hairline etchant is 8% by mass.

[0091] Comparative Example 1

[0092] The only difference from Example 1 is that the hairline etching agent does not contain reducing organic acids.

[0093] Comparative Example 2

[0094] The only difference from Example 1 is that the hairline etching agent does not contain nitrophenol.

[0095] Comparative Example 3

[0096] The only difference from Example 1 is that the hairline etching agent does not contain ferric chloride.

[0097] Comparative Example 4

[0098] The only difference from Example 1 is that the reducing organic acid in the hairline etching agent is replaced with an equal amount of acetic acid.

[0099] Comparative Example 5

[0100] The only difference from Example 1 is that the nitrophenol in the hairline etching agent is replaced with an equal amount of phenol.

[0101] Comparative Example 6

[0102] The only difference from Example 1 is that the ferric chloride in the hairline etching agent is replaced with an equal amount of ferrous chloride.

[0103] Comparative Example 7

[0104] The only difference from Example 1 is that the hairline etchant is replaced with hydrochloric acid with a mass concentration of 11%.

[0105] To verify the accuracy of the corrosion effect of the present invention, the parallel samples of the above embodiments and comparative examples were tested for hairline cracks according to GB / T10121-2008 Steel Tower Hairline Cracking Magnetic Particle Test Method, and then compared with the corrosion results of the present invention, as shown in Table 1 below.

[0106] Table 1

[0107]

[0108] As can be seen from the comparison in Table 1, when using the hairline etching agent of the present invention for hairline detection and analysis, the analysis results are basically consistent with the magnetic particle testing method. Furthermore, the introduction of ultrasonic treatment in the process can further enhance the accuracy of hairline etching, and the analysis results are consistent with the magnetic particle testing method, demonstrating good detection accuracy.

[0109] In summary, the solution provided by this invention optimizes the ratio of the etchant, reduces the amount of inorganic acid, and introduces other auxiliary reagents to ensure efficient etching of hairline patterns while avoiding linear etching marks, thus significantly improving the accuracy of hairline pattern detection and analysis.

[0110] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0111] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0112] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A hairline etching agent for structural steel, characterized in that, The hairline etching agent comprises, by weight percentage: Inorganic acid 10-12%, reducing organic acid 3-5%, nitrophenol 1-2%, ferric chloride 1-5%, balance water.

2. The hairline etching agent as described in claim 1, characterized in that, The inorganic acids include hydrochloric acid and / or sulfuric acid.

3. The hairline etching agent as described in claim 1, characterized in that, The reducing organic acid includes one or a combination of at least two of formic acid, oxalic acid, citric acid, tartaric acid, or glycolic acid.

4. The hairline etching agent as described in claim 1, characterized in that, The nitrophenols include p-nitrophenol and / or trinitrophenol.

5. A method for hairline corrosion of structural steel, characterized in that, The hairline etching method includes: etching a structural steel sample with a hairline etching agent as described in any one of claims 1-4.

6. The hairline etching method as described in claim 5, characterized in that, The corrosion temperature is 70-90℃.

7. The hairline etching method as described in claim 5, characterized in that, The corrosion time is 5-30 minutes.

8. The hairline etching method as described in claim 5, characterized in that, The corrosion process is aided by ultrasound.

9. The hairline etching method as described in claim 5, characterized in that, The frequency of the ultrasound is 30-50 kHz.

10. The hairline etching method as described in claim 5, characterized in that, The power density of the ultrasound is 0.05-0.15 W / cm². 2 .

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