Preparation method for improving pickling surface quality of X32 strip steel

Abstract

The invention discloses a preparation method for improving the pickling surface quality of X32 strip steel and an X32 pickled steel plate. The preparation method comprises the steps that hot-rolled strip steel is provided; a pickling compound agent is used for conducting pickling treatment on the hot-rolled strip steel, pickling strip steel is obtained, the pickling compound agent comprises acid liquor and a pickling accelerant, particularly hydrochloric acid is selected as the acid liquor, an ammonia nitrogen pickling accelerant is selected as the pickling accelerant, and meanwhile the mass ratio of the acid liquor to the pickling accelerant is controlled to be 9: 40-110: 1; rust and oxide scale on the surface of the strip steel can be effectively removed, the reaction rate of acid liquor and the oxide scale is greatly increased, and therefore the surface pickling quality of the X32 strip steel is improved, the performance stability of the whole band saw blade is guaranteed, and the service life of the band saw blade is prolonged.

Description

Technical Field

[0001] This application belongs to the field of metal material processing, and particularly relates to a preparation method for improving the pickling surface quality of X32 strip steel. Background Art

[0002] X32 is a high-alloy tool steel, mainly used for manufacturing the back material of bimetal saw blades. During the processes of slab heating, rough rolling, and finish rolling, oxidation occurs on the upper and lower surfaces of the X32 strip steel, generating mill scale. The mill scale firmly covers the surface of the strip steel. After pickling the strip steel, various surface quality defects such as "black bands", gray surface color after pickling, pickling color difference, and transverse folding marks may occur, resulting in a significant decrease in the hardness, strength, wear resistance, toughness, and fatigue resistance of the bimetal band saw back material X32, seriously affecting the stability of the performance of the entire band saw blade and its service life. Summary of the Invention

[0003] The embodiments of this application provide a preparation method for improving the pickling surface quality of X32 strip steel and an X32 pickled steel plate, which can improve the surface quality of the strip steel after pickling.

[0004] In a first aspect, the embodiments of this application provide a preparation method for improving the pickling surface quality of X32 strip steel, including: providing hot-rolled strip steel; pickling the hot-rolled strip steel with a pickling compound agent to obtain pickled strip steel, wherein the pickling compound agent includes an acid solution and a pickling accelerator, the acid solution is hydrochloric acid, the pickling accelerator is an ammonia-nitrogen pickling accelerator, and the mass ratio of the acid solution to the pickling accelerator is 9:40 to 110:1.

[0005] According to the embodiments of the first aspect of this application, the concentration of ammonia-nitrogen in the ammonia-nitrogen pickling accelerator is 0.5 mg / mL to 0.7 mg / mL.

[0006] According to the embodiments of the first aspect of this application, the concentration of ammonia-nitrogen in the ammonia-nitrogen pickling accelerator is 0.684 mg / mL.

[0007] According to the embodiments of the first aspect of this application, the mass ratio of the acid solution to the pickling accelerator is 20:1 or 15:1.

[0008] According to the embodiments of the first aspect of this application, before the step of pickling the hot-rolled strip steel with a pickling compound agent to obtain pickled strip steel, descaling treatment is also included to obtain descaled strip steel.

[0009] According to the embodiments of the first aspect of this application, after the step of pickling the hot-rolled strip steel with a pickling compound agent to obtain pickled strip steel, drying treatment is also included to dry the pickled strip steel with a dryer, wherein the height of the bottom guide plate of the dryer is 120 cm - 130 cm.

[0010] According to an embodiment of the first aspect of the present application, the speed of descaling treatment is 10 m / min - 50 m / min.

[0011] According to an embodiment of the first aspect of the present application, the temperature of pickling treatment is 40°C - 80°C.

[0012] According to an embodiment of the first aspect of the present application, the speed of pickling treatment is 10 m / min - 120 m / min.

[0013] In a second aspect, the present application provides an X32 pickled steel plate. An X32 pickled strip steel with no residual scale on the surface is prepared according to the above preparation method.

[0014] The preparation method for improving the pickling surface quality of X32 strip steel according to the embodiments of the present application includes: providing hot-rolled strip steel; pickling the hot-rolled strip steel with a pickling compound agent to obtain pickled strip steel, wherein the pickling compound agent includes an acid solution and a pickling accelerator. In particular, by selecting hydrochloric acid as the acid solution and ammonia-nitrogen pickling accelerator as the pickling accelerator, and simultaneously controlling the mass ratio of the acid solution to the pickling accelerator to be 9:40 - 110:1, it can effectively remove rust and scale on the surface of the strip steel, greatly accelerate the reaction rate between the acid solution and the scale, thereby improving the surface pickling quality of X32 strip steel, ensuring the stability of the performance of the entire band saw blade and extending its service life. Detailed implementation manners

[0015] In order to make the application purpose, technical solution and beneficial technical effects of the present application clearer, the present application will be further described in detail below with reference to embodiments. It should be understood that the embodiments described in this specification are only for explaining the present application and not for limiting the present application.

[0016] For simplicity, the present application only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form a range not explicitly recorded; and any lower limit can be combined with other lower limits to form a range not explicitly recorded. Similarly, any upper limit can be combined with any other upper limit to form a range not explicitly recorded. In addition, although not explicitly recorded, each point or single value between the range endpoints is included in this range. Thus, each point or single value can be used as its own lower limit or upper limit and combined with any other point or single value or combined with other lower limits or upper limits to form a range not explicitly recorded.

[0017] It should be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0018] Unless otherwise specified, the values of the various parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the embodiments of this application). Unless otherwise specified, the test temperature for the various parameters mentioned in this application is 25°C and the test pressure is standard atmospheric pressure.

[0019] The above application content of this application does not intend to describe every disclosed embodiment or every implementation mode in this application. The following description more specifically gives examples of exemplary embodiments. Throughout the application, guidance is provided through a series of embodiments, and these embodiments can be used in various combinations. In each instance, the enumeration is only a representative group and should not be construed as exhaustive.

[0020] In terms of improving the surface quality of pickled strip steel, patent document CN111534673A discloses a method for improving the surface quality of pickled strip steel. The method includes sequentially performing primary cooling and secondary cooling on the hot-rolled coil. The secondary cooling is carried out by lifting the hot-rolled coil after primary cooling into a water-cooling tank filled with industrial circulating water. By using water-cooling tank cooling, it can obtain thin and uniform scale throughout the coil, and there is no scale residue on the surface of the pickled strip steel, and the surface quality is good. However, this method belongs to the process adjustment before pickling and does not involve changing the pickling process, increasing the process path. Patent document CN117488190A discloses a medium-high carbon steel 65Mn pickled plate and its preparation method. Through research on the welding process, it improves the weld quality, solves the technical problems of poor welding performance and easy breakage of 65Mn, and improves the surface quality of pickled 65Mn welded strip steel. However, this invention focuses on improving the weld quality and does not pay attention to the impact of pickling on the surface quality of strip steel.

[0021] To solve the problems of the prior art, the embodiments of this application provide a preparation method for improving the surface quality of pickled X32 strip steel and X32 pickled steel plates.

[0022] An embodiment of the present application provides a preparation method for improving the pickling surface quality of X32 strip steel, including: providing hot-rolled strip steel; pickling the hot-rolled strip steel with a pickling compound agent to obtain pickled strip steel, wherein the pickling compound agent includes an acid solution and a pickling accelerator, the acid solution is hydrochloric acid, the pickling accelerator is an ammonia-nitrogen pickling accelerator, and the mass ratio of the acid solution to the pickling accelerator is 9:40 to 110:1.

[0023] Exemplarily, the mass ratio of the acid solution to the pickling accelerator is 10:1, 11:1, 12:1, 13:1, 13.5:1, 14:1, 14.5:1, 15:1, 15.5:1, 16:1, 16.5:1, 17:1, 17.5:1, 18:1, 18.5:1, 19:1, 19.5:1, 20:1, 20.5:1, 21:1, 21.5:1, 22:1, 23.5:1, 24:1, 25:1.

[0024] According to the embodiment of the present application, hydrochloric acid is selected as the acid solution and an ammonia-nitrogen pickling accelerator is selected as the pickling accelerator. Hydrochloric acid has strong acidity and can chemically react with iron oxides in the scale to generate soluble ferric chloride and water. This process not only decomposes the scale but also converts it into a more easily treatable substance through chemical reactions. Moreover, the ammonia-nitrogen pickling accelerator contains components that can change the surface tension of the metal, and these components can play a role in physical peeling during the pickling process to help remove the scale. Controlling the mass ratio of the acid solution to the pickling accelerator to be 9:40 to 110:1 accelerates the reaction rate between the acid solution and the scale, and the strip steel surface is pickled more cleanly. This combined use method not only improves the pickling efficiency but also ensures that the pickled metal surface is cleaner, providing a good foundation for subsequent processes such as electroplating, enameling, or rolling.

[0025] In some optional embodiments, the concentration of ammonia-nitrogen in the ammonia-nitrogen pickling accelerator is 0.5 mg / mL to 0.7 mg / mL.

[0026] Exemplarily, the concentration of ammonia-nitrogen in the ammonia-nitrogen pickling accelerator is 0.5 mg / mL, 0.51 mg / mL, 0.52 mg / mL, 0.53 mg / mL, 0.54 mg / mL, 0.55 mg / mL, 0.6 mg / mL, 0.61 mg / mL, 0.62 mg / mL, 0.63 mg / mL, 0.64 mg / mL, 0.65 mg / mL, 0.66 mg / mL, 0.67 mg / mL, 0.675 mg / mL, 0.68 mg / mL, 0.682 mg / mL, 0.684 mg / mL, 0.685 mg / mL, 0.688 mg / mL, 0.69 mg / mL, 0.7 mg / mL.

[0027] Preferably, the concentration of ammonia nitrogen in the ammonia nitrogen pickling promoter is 0.55 mg / mL to 0.7 mg / mL.

[0028] In some alternative embodiments, the concentration of ammonia nitrogen in the ammonia nitrogen pickling promoter is 0.684 mg / mL.

[0029] According to the embodiments of the present application, controlling the concentration of ammonia nitrogen in the ammonia nitrogen pickling promoter to 0.5 mg / mL to 0.7 mg / mL can optimize the chemical properties of the pickling solution, making it easier to react with mill scale. This chemical reaction can decompose the mill scale, making it loose and easy to peel off from the strip surface.

[0030] In some alternative embodiments, the mass ratio of the acid solution to the pickling promoter is 20:1 or 15:1.

[0031] According to the embodiments of the present application, if the mass ratio of the acid solution to the pickling promoter is too high, the pickling reaction ability will be limited, which may lead to incomplete removal of mill scale, leaving residues and affecting the surface quality after pickling; if it is too low, the pickling reaction may be too intense, increasing the risk of over-corrosion of the metal matrix, especially when the treatment time is long or the temperature is high. Therefore, controlling the mass ratio of the acid solution to the pickling promoter to 20:1 or 15:1 can ensure that the strip is not prone to over-corrosion and hydrogen embrittlement during pickling, and can further effectively remove rust and mill scale on the strip surface.

[0032] In some alternative embodiments, before the step of pickling the hot-rolled strip with the pickling compound to obtain the pickled strip, it further includes descaling the hot-rolled strip to obtain the descaled strip.

[0033] In some alternative embodiments, after the step of pickling the hot-rolled strip with the pickling compound to obtain the pickled strip, it further includes drying the pickled strip with a dryer, wherein the height of the bottom guide plate of the dryer is 120 cm - 130 cm.

[0034] According to the embodiments of the present application, in order to prevent the upper and lower surfaces of the strip from frequently contacting the bottom guide plate of the dryer during the transfer process after leaving the pickling tank and causing scratch marks, if the guide plate is too high, the strip will vibrate more severely and run unstably, and if the guide plate height is too low, the contact frequency between the strip and the guide plate will increase. Therefore, the height of the bottom guide plate of the dryer is 120 cm - 130 cm.

[0035] In some alternative embodiments, the speed of the descaling treatment is 10 m / min - 50 m / min.

[0036] Exemplarily, the speed of descaling treatment is 10 m / min, 15 m / min, 20 m / min, 25 m / min, 30 m / min, 35 m / min, 40 m / min, 45 m / min, 50 m / min.

[0037] According to the embodiments of the present application, if the descaling treatment speed is too slow, over-pickling may occur on the surface of the strip steel, manifested as a brownish-black or dark black surface, which affects the surface quality of the strip steel and its subsequent processing performance. If the speed is too fast, the scale may not be fully removed and remain on the surface of the strip steel, affecting the pickling effect and subsequent processing quality. Therefore, setting the descaling treatment speed to 10 m / min - 50 m / min can peel off the scale on the surface of the strip steel or loosen its combination with the substrate, providing favorable conditions for the reaction between the pickling solution and the scale.

[0038] In some alternative embodiments, the temperature of the pickling treatment is 40°C - 80°C.

[0039] Exemplarily, the temperature of the pickling treatment is 40°C, 50°C, 60°C, 70°C, 80°C.

[0040] According to the embodiments of the present application, too high a temperature for pickling treatment of strip steel will accelerate the pickling reaction, which may lead to over-corrosion of the strip steel when it stays in the pickling solution for a relatively short time. Too low a temperature will make the reaction speed relatively slow, reduce the efficiency of removing oxides and pollutants, prolong the pickling time, and thus reduce the production efficiency. Therefore, setting the pickling treatment temperature to 40°C - 80°C can obtain the best pickling effect.

[0041] In some alternative embodiments, the speed of the pickling treatment is 10 m / min - 120 m / min.

[0042] Exemplarily, the speed of the pickling treatment is 10 m / min, 11 m / min, 12 m / min, 13 m / min, 14 m / min, 15 m / min, 16 m / min, 17 m / min, 18 m / min, 19 m / min, 20 m / min, 50 m / min, 80 m / min, 90 m / min, 120 m / min.

[0043] According to the embodiments of the present application, too long a pickling treatment time for strip steel will cause the strip steel to stay in the pickling solution for too long, making its surface rough and pitted under the action of the pickling solution, seriously affecting the quality of the strip steel. Too short a time may result in incomplete removal of the scale and impurities. Therefore, setting the pickling treatment speed to 10 - 120 m / min can obtain the best pickling effect.

[0044] The present application provides an X32 pickled steel plate, and an X32 pickled strip steel with no residual scale on the surface is prepared according to the above preparation method.

[0045] In some alternative embodiments, the hot-rolled strip, by mass percentage, comprises: C: 0.25% - 0.42%, Si: 0.1% - 0.55%, Mn: 0.1 - 1.55%, P: ≤0.02%, S: ≤0.02%, Cr: 3.5 - 5.0%, Mo: 1.0 - 2.5%, Ni: 0.5 - 2.0%, V: ≤0.5%, Al: ≤0.06%, and the balance is Fe and inevitable impurities.

[0046] In some alternative embodiments, the thickness of the hot-rolled strip is 1.5 - 15 mm and the width is 650 - 2250 mm.

[0047] The preparation method for improving the pickling surface quality of X32 strip steel according to the embodiments of the present application includes: providing a hot-rolled strip; pickling the hot-rolled strip with a pickling compound agent to obtain a pickled strip. The pickling compound agent includes an acid solution and a pickling accelerator. In particular, by selecting hydrochloric acid as the acid solution and an ammonia-nitrogen pickling accelerator as the pickling accelerator, and controlling the mass ratio of the acid solution to the pickling accelerator to be 9:40 - 110:1, it can effectively remove rust and scale on the strip surface, greatly accelerate the reaction rate between the acid solution and the scale, thereby improving the surface pickling quality of X32 strip steel, ensuring the stability of the performance of the entire bandsaw blade and extending its service life. Compared with the existing process, the present invention does not change the process and the processing technology. The production method is simple and controllable. The preparation method for improving the pickling surface quality of X32 strip steel according to the present invention is an effective method for improving the surface quality during the pickling of high-strength bimetallic backing material X32.

[0048] Embodiment

[0049] The following embodiments more specifically describe the content disclosed in the present application. These embodiments are only for illustrative purposes, because various modifications and changes within the scope of the content disclosed in the present application are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and all instruments used in the embodiments are commercially available.

[0050] It should be noted that the mass concentration of the acid solution or accelerator described in the following embodiments, its unit is actually equivalent to g / L. For example, a hydrochloric acid solution with a mass concentration of 20% is equivalent to a hydrochloric acid solution of 20 g / L; an ammonia-nitrogen pickling accelerator with a mass concentration of 5% is equivalent to an ammonia-nitrogen pickling accelerator of 5 g / L.

[0051] The manufacturer of the pickling accelerator described in the present invention is Shenzhen Langwei Electric Co., Ltd.; the product name is: Pickling Accelerator VIDCEL 1121, and the product number is L808347QD.

[0052] Example 1

[0053] The chemical composition and its mass percentage content of the X32 strip steel are: C: 0.31%, Si: 0.17%, Mn: 0.85%, S: 0.002%, P: 0.01%, Al: 0.02%, Cr: 3.5%, Ni: 0.5%, Mo: 1.5%, V: 0.3%, and the rest are Fe and inevitable impurities. The specifications of the strip steel are 2.7mm×2250mm×full length.

[0054] The strip steel is rolled into a hot-rolled steel coil by a hot rolling mill. Before the hot-rolled steel coil enters the pickling tank, it undergoes descaling treatment by a descaling device. 10L of ammonia-nitrogen pickling accelerator with a mass concentration of 5% is added to 50L of hydrochloric acid solution with a mass concentration of 20%; the pickling treatment speed is 15 meters per minute; the height of the bottom guide plate in the dryer is reduced by 5mm, and the actual height of the guide plate is 1295mm.

[0055] After treating the strip steel according to the above method, the surface of the strip steel is grayish-white, without residual scale and obvious scratches.

[0056] Example 2

[0057] The chemical composition and its mass percentage content of the X32 strip steel are: C: 0.30%, Si: 0.21%, Mn: 1.18%, S: 0.0015%, P: 0.01%, Al: 0.03%, Cr: 3.8%, Ni: 0.7%, Mo: 1.8%, V: 0.4%, and the rest are Fe and inevitable impurities. The specifications of the strip steel are 4.3mm×2250mm×full length.

[0058] The strip steel is rolled into a hot-rolled steel coil by a hot rolling mill. Before the hot-rolled steel coil enters the pickling tank, it undergoes descaling treatment by a descaling device. 10L of ammonia-nitrogen pickling accelerator with a mass concentration of 10% is added to 50L of hydrochloric acid solution with a mass concentration of 30%; the pickling treatment speed is 25 meters per minute; the height of the bottom guide plate in the dryer is reduced by 8mm, and the actual height of the guide plate is 1292mm.

[0059] After treating the strip steel according to the above method, the surface of the strip steel is grayish-white, without residual scale and obvious scratches.

[0060] Comparative Example 1

[0061] The only difference from Example 1 is that:

[0062] Add 10 L of ammonia nitrogen promoter with a mass concentration of 0.8% to 50 L of hydrochloric acid solution with a mass concentration of 20%.

[0063] After treating the strip steel according to the above method, the surface of the strip steel is grayish-black and there is more scale residue.

[0064] Comparative Example 2

[0065] The difference from Example 1 is only that:

[0066] No promoter is added to 50 L of hydrochloric acid solution with a mass concentration of 20%.

[0067] After treating the strip steel according to the above method, the surface of the strip steel is grayish-black and there is more scale residue.

[0068] Comparative Example 3

[0069] The difference from Example 1 is only that:

[0070] Add 50 L of ammonia nitrogen promoter with a mass concentration of 25% to 45 L of hydrochloric acid solution with a mass concentration of 5%.

[0071] After treating the strip steel according to the above method, the surface of the strip steel is grayish-black and over-pickling pits appear on the surface.

[0072] Comparative Example 4

[0073] The difference from Example 1 is only that:

[0074] Replace the acid solution - hydrochloric acid with sulfuric acid.

[0075] After treating the strip steel according to the above method, the surface of the strip steel is grayish-black and there is more scale residue, and there are ferric sulfate acid spots that are not pickled cleanly.

[0076] Comparative Example 5

[0077] The difference from Example 1 is only that:

[0078] Replace the acid solution - hydrochloric acid with nitric acid.

[0079] After treating the strip steel according to the above method, the surface of the strip steel is grayish-black and there is more scale residue, and the pickling efficiency is weaker than that of hydrochloric acid.

[0080] Comparative Example 6

[0081] The difference from Example 1 is only that:

[0082] Replace the ammonia nitrogen pickling promoter with an acetic acid pickling promoter.

[0083] After treating the strip steel according to the above method, the surface of the strip steel is grayish-black and there is more scale residue.

[0084] Comparative Example 7

[0085] The difference from Example 1 is only that:

[0086] The ammonia nitrogen pickling accelerator is replaced with a citric acid pickling accelerator.

[0087] After the strip steel is processed according to the above method, the surface of the strip steel is grayish-black and there is more scale residue.

[0088] Comparative Example 8

[0089] The difference from Example 1 is only that:

[0090] The height of the dryer guide plate is set to 1310 cm.

[0091] After the strip steel is processed according to the above method, there are obvious scratches on the surface of the strip steel.

[0092] Comparative Example 9

[0093] The difference from Example 1 is only that:

[0094] The height of the dryer guide plate is set to 1185 cm.

[0095] After the strip steel is processed according to the above method, there are obvious scratches on the surface of the strip steel.

[0096] The above is only the specific implementation manner of the present application. Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working process described above can refer to the corresponding process in the foregoing method embodiments and will not be repeated here. It should be understood that the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should be covered within the protection scope of the present application.

Claims

1. A preparation method for improving the pickling surface quality of X32 strip steel, characterized in that, Including: Providing hot-rolled strip steel; Pickling the hot-rolled strip steel with a pickling compound to obtain pickled strip steel, wherein the pickling compound includes an acid solution and a pickling accelerator, the acid solution is hydrochloric acid, the pickling accelerator is an ammonia-nitrogen pickling accelerator, and the mass ratio of the acid solution to the pickling accelerator is 9:40 to 110:

1.

2. The preparation method according to claim 1, wherein, The concentration of ammonia-nitrogen in the ammonia-nitrogen pickling accelerator is 0.5 mg / mL to 0.7 mg / mL.

3. The preparation method according to claim 1, characterized in that, The concentration of ammonia-nitrogen in the ammonia-nitrogen pickling accelerator is 0.684 mg / mL.

4. The preparation method according to claim 1, wherein, The mass ratio of the acid solution to the pickling accelerator is 20:1 or 15:

1.

5. The preparation method according to claim 1, characterized in that, Before the step of pickling the hot-rolled strip steel with the pickling compound to obtain pickled strip steel, it further includes descaling the hot-rolled strip steel to obtain descaled strip steel.

6. The preparation method according to claim 1, characterized in that, After the step of pickling the hot-rolled strip steel with the pickling compound to obtain pickled strip steel, it further includes drying the pickled strip steel with a dryer, wherein the height of the bottom guide plate of the dryer is 120 cm - 130 cm.

7. The preparation method according to claim 5, characterized in that, The speed of the descaling treatment is 10 m / min - 50 m / min.

8. The preparation method according to claim 1, characterized in that, The temperature of the pickling treatment is 40°C - 80°C.

9. The preparation method according to claim 1, characterized in that, The speed of the pickling treatment is 10 m / min - 120 m / min.

10. A X32 pickled steel sheet, characterized in that, X32 pickled strip steel with no residual scale on the surface is prepared by the preparation method according to any one of claims 1 - 9.