Method for observing surface defects by pickling surface of continuous casting sheet billet

Abstract

The invention provides a method for observing surface defects of a continuous casting slab through surface pickling. The method comprises the steps that refractory mortar is adopted to define an area needing to be subjected to pickling on a casting slab; the top of the refractory mortar is covered with a glass plate with holes, the acid pickling area is covered with the glass plate with holes, and a cavity structure with holes is formed between the glass plate with holes and the casting blank; putting an electromagnetic stirring magneton into the cavity structure, sucking the magneton across the glass plate by using an electromagnetic stirrer, and adjusting the magneton to the central position of the cavity structure; injecting hydrochloric acid into the cavity structure; the holes of the glass plate are covered after hydrochloric acid is injected, electromagnetic stirring is started, and electromagnetic stirring is stopped 15-25 minutes later; shoveling part of refractory mortar to serve as a hydrochloric acid solution outlet, opening the holes of the glass plate, and injecting water into the cavity structure through the holes; and observing surface defects. According to the technical scheme, the method is easy to operate, raw material consumption is reduced, the field environment is improved, the casting blank pickling time is shortened, and the pickling efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of slab surface defect detection, and in particular to a method for observing surface defects of a continuous casting slab by pickling. Background Art

[0002] The surface quality of continuous casting ingots is one of the important characteristics of steel product quality. In the red-hot state, only some very obvious surface defects such as cracks and deformation of the ingot can be observed on the surface quality of the continuous casting ingot. It is difficult to observe small cracks and shallow surface bubbles and other defects. These defects will develop into more serious product cracks in the subsequent rolling process, resulting in the scrapping of the produced products. If the quality problems of the ingots are discovered in time, they can be repaired by flame cleaning to avoid as much as possible the greater impact of surface quality problems on subsequent rolling. At present, the method of pickling the surface of continuous casting slabs to observe surface defects is to use refractory mud to enclose the area that needs to be pickled on the ingot, so that the refractory mud and the surface of the ingot form a pool, and then inject hydrochloric acid into the pool for soaking. Soak for about 20-35 minutes, dilute the acid solution with water until the surface of the ingot is clear, scrape off the refractory mud, and wait for the surface water to dry before observation.

[0003] In summary, the existing technology has the following problems: the large amount of hydrochloric acid used in pickling the surface of the continuous casting slab causes waste, the large amount of hydrochloric acid volatilization causes environmental pollution, and the long pickling time affects the process adjustment and causes subsequent quality impact. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem of how to make the pickling of the surface of the continuous casting slab more environmentally friendly and reduce the influence of the long pickling time on the subsequent casting quality.

[0005] To this end, an embodiment of the present invention provides a method for observing surface defects by pickling a continuous casting slab surface, and in particular, a method for judging surface defects by pickling a continuous casting slab surface, the method comprising:

[0006] Step 1: Use refractory clay to enclose the area that needs pickling on the ingot;

[0007] Step 2: Place the perforated glass plate on top of the refractory mud and cover the pickling area to form a cavity structure with holes between the perforated glass plate and the ingot;

[0008] Step 3: Place the electromagnetic stirring magnet into the cavity structure, use the electromagnetic stirrer to absorb the magnet through the glass plate and adjust it to the center of the cavity structure;

[0009] Step 4: injecting hydrochloric acid into the cavity structure;

[0010] Step 5: After injecting hydrochloric acid, cover the hole of the glass plate, turn on electromagnetic stirring, and turn off electromagnetic stirring after 15 to 25 minutes;

[0011] Step 6: Shovel away part of the refractory mud as the outlet for the hydrochloric acid solution, open the hole in the glass plate, and inject water into the cavity structure through the hole;

[0012] Step 7: Scrape off the refractory mud, then clean the glass plate and electromagnetic stirrer with water, and observe the surface defects after the water on the surface of the ingot is dry.

[0013] Specifically, the hole of the perforated glass plate is arranged near the edge of the glass plate.

[0014] Specifically, the diameter of the hole in the perforated glass plate is controlled to be 50-100 mm.

[0015] Specifically, in step five, the electromagnetic stirring time is controlled to be 20 minutes.

[0016] Specifically, in step five, the electromagnetic stirring time is controlled to be 25 minutes.

[0017] Specifically, the step seven specifically includes: diluting the hydrochloric acid solution with water until the surface of the ingot is clearly visible, removing the perforated glass plate and the electromagnetic stirrer, scraping off the refractory mud, and then cleaning the glass plate and the electromagnetic stirrer with water.

[0018] Specifically, the covering of the hole of the perforated glass plate is the second glass plate.

[0019] Specifically, the second glass plate is configured to be circular.

[0020] Specifically, the diameter of the second glass plate is larger than the diameter of the hole in the perforated glass plate.

[0021] Specifically, the concentration of hydrochloric acid used during pickling is 2% to 5%.

[0022] The beneficial effects of the present invention are as follows: the technical solution shortens the pickling time of the ingot and improves the pickling efficiency. It effectively reduces the volatilization of hydrochloric acid, protecting the health of workers. On-site environmental pollution is greatly reduced, the utilization rate of hydrochloric acid is improved, and the amount of hydrochloric acid used is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a flow chart of a method for observing surface defects by pickling the surface of a continuous casting slab provided by an embodiment of the present invention;

[0024] Figure 2 2 is a schematic structural diagram of the surface of a cast slab after pickling provided by an embodiment of the present invention;

[0025] Figure 3 Schematic diagram of enclosing a pickling area on the surface of a cast slab with refractory clay before pickling according to an embodiment of the present invention;

[0026] Figure 4 Schematic diagram of covering a perforated glass plate on refractory mud before pickling provided by an embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of placing an electromagnetic stirring magnet before pickling provided by an embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of a first embodiment of pickling the surface of a cast slab provided by an embodiment of the present invention;

[0029] Figure 7 This is a schematic diagram of a second embodiment of pickling the surface of a cast slab provided by an embodiment of the present invention;

[0030] Figure 8 Schematic diagram of discharging sulfuric acid solution after pickling provided by an embodiment of the present invention;

[0031] Figure 9 It is a schematic diagram of the surface of the cast slab after pickling provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] The technical solution of the present invention creates a relatively closed environment by covering the liquid surface of the pickling tank, thereby increasing the vapor pressure of hydrochloric acid in the cavity and inhibiting its volatilization, thereby reducing the amount of hydrochloric acid used and the environmental pollution caused by volatilization. Electromagnetic stirring is used to circulate the hydrochloric acid solution inside, making the concentration of the hydrochloric acid solution uniform, improving the kinetic conditions for the reaction between hydrochloric acid and the billet surface, and increasing the efficiency of pickling the billet surface.

[0034] In the embodiment of the present invention, Figure 1 , provides a method for observing surface defects by pickling the surface of a continuous casting slab, the method comprising:

[0035] Step 1: If Figure 3 As shown, refractory mud is used to enclose the area requiring pickling on the ingot;

[0036] Step 2: Cover the perforated glass plate on the top of the refractory mud and the pickling area to form a cavity structure with holes between the perforated glass plate and the ingot; Figure 4As shown, a relatively closed environment is formed, thereby increasing the vapor pressure of hydrochloric acid in the cavity and inhibiting the volatilization of hydrochloric acid. The hole of the perforated glass plate is set near the edge of the glass plate. The diameter of the hole of the perforated glass plate is controlled to be 50-100 mm.

[0037] Step 3: Place the electromagnetic stirring magnet into the cavity structure, as shown in Figure 5 As shown, the magnetic particle is attracted through the glass plate by an electromagnetic stirrer and adjusted to the center position of the cavity structure;

[0038] Step 4: If Figure 6 、 Figure 7 As shown, hydrochloric acid is injected into the cavity structure; the concentration of hydrochloric acid used during pickling is 2% to 5%, preferably, the concentration of hydrochloric acid used during pickling is 3.5%.

[0039] Step 5: After injecting hydrochloric acid, cover the hole in the glass plate and start electromagnetic stirring. After 15-25 minutes, turn off the electromagnetic stirring. The hole in the perforated glass plate is covered with a second glass plate. The second glass plate is circular. The diameter of the second glass plate is larger than the diameter of the hole in the perforated glass plate.

[0040] In step 5, the electromagnetic stirring time is controlled to 20 minutes or 25 minutes. In addition, the electromagnetic stirring time depends on the temperature of the ingot. If the ingot temperature is increased, the electromagnetic stirring time is 15 minutes. The original pickling time is 25 to 35 minutes.

[0041] Step 6: If Figure 8 As shown, part of the refractory mud is scraped off as an outlet for the hydrochloric acid solution, the hole in the glass plate is opened, and water is injected into the cavity structure through the hole;

[0042] Step 7: If Figure 9 As shown, scrape off the refractory mud, then clean the glass plate and electromagnetic stirrer with water, and observe the surface defects after the water on the surface of the ingot is dry.

[0043] Step seven specifically includes: diluting the hydrochloric acid solution with water until the surface of the ingot is clearly visible, removing the perforated glass plate and the electromagnetic stirrer, scraping off the refractory mud, and then cleaning the glass plate and the electromagnetic stirrer with water.

[0044] The technical solution and method of the present invention are simple to operate, reduce raw material consumption, improve the on-site environment, shorten the pickling time for ingots, and improve the pickling efficiency. They also effectively reduce hydrochloric acid volatilization and protect the health of workers. On-site environmental pollution is greatly reduced, the utilization rate of hydrochloric acid is improved, and the amount of hydrochloric acid used is reduced.

[0045] Example 1:

[0046] The present invention provides a method for observing surface defects by pickling the surface of a continuous casting slab, which is performed by the following steps:

[0047] Step 1: Use refractory mud to enclose the area that needs pickling on the upper surface or lower surface of the ingot, so that the refractory mud and the ingot surface form a pool. The shape of the pool is, for example, rectangular, with dimensions of: 20 mm thick * 1000 mm wide * (1000-1600 mm) long;

[0048] Step 2: Select a glass plate with holes that can completely cover the pickling area. The diameter of the hole is 50-100 mm. The hole is located at the edge to facilitate the injection of acid. For example, it is set at the edge or corner of a rectangular pool. The hole is a circular hole, and the outer edge of the hole is 200-300 mm away from the adjacent two sides.

[0049] Step 3: Cover the perforated glass plate on the refractory mud to form a cavity structure with holes;

[0050] Step 4: Place the electromagnetic stirring magneton into the cavity structure;

[0051] Step 5: Use an external electromagnetic stirrer with a speed of 200 to 3000 rpm and a magnet size of 15 to 50 mm. Suction the magnet through the glass and adjust it to the center of the cavity structure.

[0052] Step 6: Inject hydrochloric acid;

[0053] Step 7, cover the hole with a small glass plate;

[0054] Step 8: Turn on electromagnetic stirring and turn it off after 25 minutes;

[0055] Step 9: Use a tool to scrape off some of the refractory mud as an outlet, move the small glass plate, and inject water into the hole;

[0056] Step 10: dilute the acid solution with water until the surface of the ingot is clearly visible, remove the perforated glass plate and the electromagnetic stirrer, scrape off the refractory mud, and then clean the glass plate and the electromagnetic stirrer with water.

[0057] Step 11, wait for the surface of the billet to dry and then observe. Figure 2 As shown, it can be seen that the surface after pickling exposes the defects under the iron oxide scale of the ingot, which is convenient for quality inspection.

[0058] The method of the present invention is simple to operate, reduces raw material consumption, improves the on-site environment, shortens the pickling time for cast billets, and improves pickling efficiency. It effectively reduces hydrochloric acid volatilization, protecting the health of workers. It significantly reduces on-site environmental pollution, improves the utilization rate of hydrochloric acid, and reduces the amount of hydrochloric acid used by approximately 20% to 30%. Previously, when hydrochloric acid was used for soaking, the depth of the molten pool was 25 to 30 mm. Now, a molten pool depth of approximately 20 mm is sufficient.

[0059] The above description is merely an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. The various components of the present invention may be combined with each other without conflict, and any equivalent changes and modifications made by a person skilled in the art without departing from the concept and principles of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for observing surface defects by pickling the surface of a continuous casting slab, characterized in that: The method comprises: Step 1: Use refractory clay to enclose the area that needs pickling on the ingot; Step 2: Place the perforated glass plate on top of the refractory mud and cover the pickling area to form a cavity structure with holes between the perforated glass plate and the ingot; Step 3: Place the electromagnetic stirring magnet into the cavity structure, use the electromagnetic stirrer to absorb the magnet through the glass plate and adjust it to the center of the cavity structure; Step 4: injecting hydrochloric acid into the cavity structure; Step 5: After injecting hydrochloric acid, cover the hole of the glass plate, turn on electromagnetic stirring, and turn off electromagnetic stirring after 15 to 25 minutes; Step 6: Shovel away part of the refractory mud as the outlet for the hydrochloric acid solution, open the hole in the glass plate, and inject water into the cavity structure through the hole; Step 7: Scrape off the refractory mud, then clean the glass plate and electromagnetic stirrer with water, and observe the surface defects after the water on the surface of the ingot is dry.

2. The method for observing surface defects of a continuous casting slab by pickling according to claim 1, characterized in that: The holes of the perforated glass plate are positioned close to the edge of the glass plate.

3. The method for observing surface defects of a continuous casting slab by pickling according to claim 1, characterized in that: The diameter of the hole in the perforated glass plate is controlled to be 50 to 100 mm.

4. The method for observing surface defects of a continuous casting slab by pickling according to claim 1, characterized in that: In step 5, the electromagnetic stirring time is controlled to be 20 minutes.

5. The method for observing surface defects of a continuous casting slab by pickling according to claim 1, characterized in that: In step 5, the electromagnetic stirring time is controlled to be 25 minutes.

6. The method for observing surface defects of a continuous casting slab by pickling according to claim 1, characterized in that: The step seven specifically includes: diluting the hydrochloric acid solution with water until the surface of the ingot is clearly visible, removing the perforated glass plate and the electromagnetic stirrer, scraping off the refractory mud, and then cleaning the glass plate and the electromagnetic stirrer with water.

7. The method for observing surface defects of a continuous casting slab by pickling according to claim 1, characterized in that: The covering of the hole of the perforated glass plate is a second glass plate.

8. The method for observing surface defects of a continuous casting slab by pickling according to claim 7, characterized in that: The second glass plate is configured in a circular shape.

9. The method for observing surface defects of a continuous casting slab by pickling according to claim 8, characterized in that: The diameter of the second glass plate is larger than the diameter of the hole of the perforated glass plate.

10. The method for observing surface defects of a continuous casting slab by pickling according to claim 1, characterized in that: The concentration of hydrochloric acid used in pickling is 2% to 5%.

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