JP6498219B2 - Manufacturing method of products obtained by hot rolling, direct cold rolling without pickling, reduction annealing, and hot dipping - Google Patents

Description

  The present invention relates to a method for producing a hot dipped product, and more particularly, to a method for producing a product obtained by hot rolling, direct cold rolling without pickling, reduction annealing, and hot dipping.

  Conventionally, in the manufacture of cold-rolled hot-dip galvanized products, the hot-rolled sheet first passes through a continuous pickling tandem cold-rolling machine, and the iron oxide skin on the surface of the hot-rolled sheet is removed. When deforming to an appropriate thickness and performing hot-dip plating, degreasing is performed by alkali cleaning, and after reduction annealing, hot-dip galvanization is completed. However, the production of this traditional hot dip galvanized product is the biggest obstacle to energy conservation and environmental protection for steel companies due to the long process, poor production efficiency and severe environmental pollution problems caused by the pickling process. is there. Further, since a large amount of iron oxide is removed in the pickling process, the yield of the product is lowered. It should be noted that a highly corrosive acid is required for production facilities and requires a stage such as treatment of waste acid, which increases production and maintenance costs. Therefore, the development of hot-dip galvanized products and their manufacturing processes, that is, the removal of the pickling process, has been an old dream for thin strip manufacturing companies and has important implications for the sustainable development of steel companies. There is.

  Patent Nos. US6258186B1 and KR100905563B1 disclose a method for producing hot-rolled hot-dip galvanized products that do not require pickling at high speed. Regarding the basic principle, instead of pickling, a reducing gas such as hydrogen gas is used to reduce the iron oxide skin on the surface of the hot rolled steel strip. However, since the reduction rate of the iron oxide skin is slow, the operation of the entire production line is affected. Therefore, in the above patent, ferric oxide in the oxide is controlled by controlling the cooling rate in the process of winding the hot-rolled steel strip in order to accelerate the reduction and match the reduction rate and the galvanization rate. The content is improved so as to be 20% or more. Although ferric oxide is relatively easy to reduce, its effect is very limited. Therefore, the development of the entire technology is still limited by the reduction rate and efficiency.

  Regarding the examination on the use performance of the iron oxide skin on the surface of the hot rolled sheet, JP 06-033449 discloses a steel plate called “tight scale”, and the iron oxide skin on the surface of the steel plate is mainly tetraoxide. It is made of ferrous iron, and its structure is dense. In the process of deformation in the subsequent finishing process, the iron oxide skin is deformed together with the steel plate without being dropped and used with the iron oxide skin attached. Since the user's requirement is satisfied, cold rolling with an iron oxide skin is not performed later. Chinese application 201010235928. No. X, 201010298939.2, 200710010183.5, 201010110116.5, 201020109526.2, 201010189410.7, and 2005100047958.7 disclose a method for producing steel for automobile frames that does not require pickling. Yes. In all the above patents, the iron oxide skin on the surface of the hot rolled sheet is mainly composed of triiron tetroxide by controlling the hot rolling process. All of the above patents relate to the use of hot-rolled sheets with an iron oxide skin attached, and when the hot-rolled steel sheet with iron oxide skin is deformed, it is bent and relates to cold rolling deformation It does not relate to subsequent hot dip galvanizing or hot dip plating of other alloys.

The present invention provides a method for producing a product obtained by hot rolling, pickling-free direct cold rolling, reduction annealing, and hot dipping in response to a lack of traditional hot dip galvanizing processes. Objective. Direct reduction after hot rolling and cold rolling, and then hot dipping to remove pickling and related processes, and the process is short, efficient and low cost. The production of a type of hot dip plating product can be realized. Moreover, the structure of the iron oxide skin on the surface of the hot rolled sheet is mainly composed of Fe ₃ O ₄ and FeO, and the thickness of the iron oxide skin is relatively thin. By cold rolling with the iron oxide skin, And other related processes.

The manufacturing method of the product obtained by hot rolling according to the present invention, direct cold rolling without pickling, reduction annealing, and hot dipping,
After descaling the slab, rough rolling by a rough rolling mill, finish rolling by a finishing mill, cooling by a cooling device, and winding by a coiler are sequentially performed, and the rolling temperature is lowered to reduce the rolling speed. By improving the thickness, the thickness of the iron oxide skin is reduced, and the cooling rate and rolling speed after rolling are controlled simultaneously, thereby controlling the structure of the iron oxide skin on the surface of the hot rolled sheet, A hot rolling process performed by a hot rolling unit that improves the adhesive strength of the steel and reduces the thickness of the iron oxide skin,
By optimizing the cold rolling process parameters including rolling pressure, tension, deformation rate and rolling pass, and using the rolling lubricant, the iron oxide skin is plastically deformed along with the substrate during the cold rolling process. Thus, the surface quality is good, a plate with a good plate shape is obtained, a cold rolling process performed by a cold rolling unit,
Reduction annealing performed in a reduction furnace that introduces a reducing gas and controls the temperature and time of reduction to thoroughly reduce the iron oxide skin and cool it to the temperature when the strip enters the galvanizing pot. Process,
After the reduction annealing step, a hot dip plating step is performed, in which the galvanizing pot is directly put into a galvanizing pot and retained for several seconds to complete hot dip plating.

  The manufacturing method of the present invention removes oil stains and dust remaining on the surface in the process of cold rolling using an alkaline degreasing agent in a degreasing rinse machine after the cold rolling step, rinses, and dries A degreasing step is further included.

  In the hot rolling step, the milling temperature is 1100 to 1250 ° C., the final rolling temperature is 800 to 900 ° C., the winding temperature is 550 to 600 ° C., and the rolling speed is 8 to 20 m / s, The cooling rate after rolling is 7 to 30 ° C./s.

  The tapping temperature is 1150 to 1200 ° C., the final rolling temperature is 840 to 870 ° C., the winding temperature is 550 to 570 ° C., the rolling speed is 14 to 18 m / s, and the cooling speed is 15 to 20 ° C./s.

  The tapping temperature is 1170 or 1200 ° C., the final rolling temperature is 850 or 860 ° C., the winding temperature is 550 or 560 ° C., the rolling speed is 17 or 18 m / s, and the cooling speed is 19 or 20 ° C./s.

In the hot rolling step, the thickness of the obtained hot rolled sheet is 1.0 to 6 mm, the average thickness of the iron oxide skin on the surface of the hot rolled sheet is 5 to 10 μm, and the structure of the iron oxide skin Is mainly composed of Fe ₃ O ₄ and FeO, in which the content of Fe ₃ O ₄ is 50% by weight or more.

The hot rolled sheet has a thickness of 1.5 to ₄ mm, and the content of Fe ₃ O ₄ is 65% or more.

  In the cold rolling process, rolling is completed within 1 to 2 passes, and the deformation rate for each pass is controlled to 1.0% to 90%.

The rolling is completed in one pass, and the deformation rate is controlled to 50% to 80%.
In the cold rolling step, deionized water or palm oil is used as the rolling emulsion, and the cold rolling reduction ratio is 1.0% to 90%.

The cold rolling reduction ratio is 50% to 80%.
In the reduction annealing step, the reduction temperature is 500 to 1000 ° C., the reduction time is 60 to 300 s, and the reducing gas is a mixture of H ₂ or CO and an inert gas, in which the concentration of H ₂ or CO Does not fall below 3%.

The reduction temperature is 750 to 950 ° C., the residence time is 120 to 300 s, and the concentration of H ₂ or CO is 10% to 75%.

The reduction temperature is 800 ° C., 850 ° C. or 900 ° C., the residence time is 180 s, 240 s or 300 s, and the concentration of H ₂ or CO is 15%, 25% or 30%.

In the reduction annealing step, H ₂ or CO that does not participate in the reaction is cycled.
In the hot dip plating process, the hot dip galvanized product obtained includes hot dip galvanizing, hot dip zinc-aluminum-magnesium plating, hot dip aluminum-zinc plating or hot dip aluminum-silicon plating product.

  The manufacturing method of products obtained by hot rolling, direct cold rolling without pickling, reduction annealing, and hot dipping according to the present invention does not require a pickling unit and the process is shorter than the traditional process. In addition to being an efficient process and capable of satisfying actual demand, it is not necessary to remove the iron oxide skin by pickling as compared with the traditional technology related to hot dip galvanization. Since a corrosive medium such as sulfuric acid is not used, the problem of environmental pollution due to pickling can be fundamentally solved. According to the present invention, hot-dip galvanized products having different thickness specifications can be obtained, and in particular, thick hot-dip galvanized products can be obtained. In addition, the obtained product is not strictly required for the surface quality, and there are some requirements for corrosion resistance and mechanical properties, for example, various construction steels, power facility steels, highways and various bridge guardrails. Especially useful in areas such as warehouse and plant steel.

It is a schematic diagram which shows the process route of the manufacturing method of the product obtained by the hot rolling in one Example of this invention, the direct cold rolling which does not need pickling, reduction annealing, and hot dipping. It is a gold phase micrograph of the cross section of the iron oxide skin after the hot-rolled sheet obtained in Application Example 1 of the present invention has undergone 50% cold rolling. It is a surface form photograph of the iron oxide skin after the hot-rolled sheet obtained in Application Example 1 of the present invention has undergone 50% cold rolling. It is a scanning photograph of the section of the galvanized board obtained in application example 1 of the present invention. It is a photograph of the surface after the galvanized board obtained in application example 1 of the present invention bent 180 degrees. It is the scanning of the cross section of the zinc-aluminum-magnesium plating plate obtained in the application example 2 of this invention.

  In order to make the above objects, features, and advantages of the present invention clearer and easier to understand, specific embodiments of the present invention will be described in detail below with reference to the drawings. First, it should be explained that the present invention is not limited to the following embodiments, and those skilled in the art understand the present invention based on the gist reflected in the following embodiments, and based on the gist of the present invention. Therefore, each technical term should be understood in the widest range. In the drawings, the same reference numeral indicates the same element.

  FIG. 1 is a diagram showing a process route of a method for producing a product obtained by hot rolling, direct cold rolling without pickling, reduction annealing, and hot dipping in one embodiment of the present invention. As shown in the figure, the method for manufacturing a galvanized product includes the following steps.

  (1) A hot rolling process is performed by a hot rolling unit. In this process, after the hot rolled plate 1 is descaled, rough rolling by the rough rolling mill 2, finish rolling by the finishing mill 3, cooling by the cooling device 4, and winding by the coiler 5 are sequentially performed. By reducing the temperature and improving the rolling speed, the thickness of the iron oxide skin is reduced, and the cooling rate and the winding speed after rolling are simultaneously controlled, thereby forming the iron oxide skin on the surface of the hot rolled sheet. Is controlled to improve the adhesive strength of the iron oxide skin to obtain a hot-rolled sheet that is relatively thin and has a specific iron oxide skin configuration. This is not only advantageous for improving the reduction rate and guaranteeing thorough reduction, but also for preventing hot-rolled sheets from falling off when cold rolled with iron oxide skin. It is advantageous.

  (2) A cold rolling process is performed by a cold rolling unit. In this process, the hot-rolled sheet is cold-rolled together with the iron oxide skin, rolled to an appropriate thickness as necessary, and the rolling parameters are adjusted in the course of rolling, and the rolling pressure, tension, deformation By optimizing the cold rolling process parameters including the rolling rate and rolling pass, and using the rolling lubricant, the iron oxide skin can be applied to the substrate without causing phenomena such as falling off and sticking to the roller during the cold rolling process. Accordingly, it is ensured that plastic deformation is good, and a plate with iron oxide skin having a good surface quality and a good plate shape is obtained.

  (3) A degreasing process is performed by the degreasing rinse machine 6. In the said process, the oil stain | pollution | contamination and dust which remained on the surface in the process of cold rolling are removed using an alkaline degreasing agent, and it rinses and dries. When pure water is used in cold rolling, it is not necessary to use an alkaline degreasing agent in this step.

  (4) A reduction annealing process is performed in a reduction annealing furnace. In this process, after being put into a reduction furnace, it is passed through a heating zone 7 and a soaking zone 8 and a reducing gas is introduced, and a reduction of 60 to 300 s is performed at 500 to 1000 ° C. by double control over temperature and time. The iron oxide skin is thoroughly reduced, passed through the cooling zone 9, and cooled to the temperature at which the steel strip enters the galvanizing pot, and the temperature is generally about 460 ° C.

  (5) The hot dip galvanizing tank 10 is charged to perform the hot dip plating process. In this process, after the reduction annealing process, it is directly put into a hot dip galvanizing tank 10 (that is, a galvanizing pot) and retained for several seconds to complete hot dip plating.

When the test and calculation were repeated, in the above step (1), the rolling temperature was 1100 to 1250 ° C, the final rolling temperature was 800 to 900 ° C, the winding temperature was 550 to 600 ° C, and the rolling speed was The cooling rate after rolling is controlled to 7 to 30 ° C./s to 8 to 20 m / s. The tapping temperature is 1150 to 1200 ° C., the final rolling temperature is 840 to 870 ° C., the winding temperature is 550 to 570 ° C., the rolling speed is 14 to 18 m / s, and the cooling speed is 15 to 20 It is preferable that it is ° C / s. The tapping temperature is 1170 or 1200 ° C., the final rolling temperature is 850 or 860 ° C., the winding temperature is 550 or 560 ° C., the rolling speed is 17 or 18 m / s, and the cooling speed is 19 or 20 More preferably, it is ° C / s. The thickness of the hot rolled sheet obtained by the above control is 1.0 to 6 mm, preferably 1.5 to 4 mm, which is much thinner than the prior art, and the iron oxide skin on the surface of the hot rolled sheet (The average thickness of the iron oxide skin on the surface of the hot-rolled sheet is a typical position on the hot-rolled sheet, for example, the head, the middle, the tail and the side part) This is the result obtained by measuring the thickness at at least three points, and dividing the total thickness of the iron oxide skin measured at each point by the total number of survey points). The iron oxide skin is mainly composed of Fe ₃ O ₄ and FeO, and the content of Fe ₃ O ₄ is 50% by weight or more, preferably 65% by weight or more. Thereby, since the thickness of the iron oxide skin can be made relatively thin, it is advantageous for reduction, and since the adhesive strength is good, it is advantageous for cold rolling with the skin attached.

  In the above step (2), deionized water or palm oil is used as the rolling emulsion, the cold rolling reduction is 1.0% to 100%, and preferably the cold rolling reduction is 50% to 80. %. Rolling is completed within 1 to 2 passes, and the deformation rate for each pass is controlled to 1.0% to 100%. More preferably, the rolling is completed in one pass and the deformation rate is controlled to 50% to 80%.

  By the above cold rolling control, the iron oxide skin does not drop off and does not stick to the roller during the cold rolling process, and deforms well with the substrate, has good surface quality, and has a good plate shape. A plate with iron oxide skin can be obtained.

In the step (4), the reducing gas is a mixture of H ₂ or CO and an inert gas, and the concentration of H ₂ or CO does not fall below 3%. The reduction temperature is preferably 750 to 950 ° C., the residence time is 120 to 300 s, and the concentration of H ₂ or CO is preferably 10% to 75%. More preferably, the reduction temperature is 800 ° C., 850 ° C. or 900 ° C., the residence time is 180 s, 240 s or 300 s, and the concentration of H ₂ or CO is 15%, 25% or 30%.

In the above step (4), the yield of the metal is improved by reducing the iron oxide skin to pure iron. At the same time, the reducing gas, H ₂ or CO, is oxidized to H ₂ O or CO ₂ without causing secondary pollution to the environment. H ₂ or CO that does not participate in the reaction can be cycled.

  The hot dip plated product obtained in the above step (5) includes hot dip galvanized, hot dip zinc-aluminum-magnesium plated, hot dip aluminum-zinc plated, hot dip aluminum-silicon plated, and other hot-dip alloy plated products.

  Hereinafter, with reference to application examples and drawings, a process technique for directly cold-rolling the hot-rolled sheet according to the present invention by pickling and reducing and hot-dip galvanizing will be described in detail. .

  The slab was heated to 1200 ° C. and stayed in the furnace for 180 minutes. The tapping temperature was 1100 ° C. After descaling with high-pressure water, rough rolling was performed, descaling was again performed with high-pressure water, and finish rolling was performed. The initial temperature of finish rolling is 980 ° C., the final temperature is 870, the coiling temperature is 600 ° C., the rolling speed is 20 m / s, and the cooling rate after rolling is 8 ° C./s. . The thickness of the obtained hot-rolled sheet was 3.6 mm, the average thickness of the iron oxide skin on the surface was 8 μm, among which the content of triiron tetroxide was at least 50%. An emulsion or pure water was used as the lubricant. The hot-rolled sheet was cold-rolled with an iron oxide skin and cold-rolled until the thickness became 1.8 mm, and the deformation rate was 50%. After washing with an alkaline solution (when rolling is lubricated with pure water, alkali washing is not necessary, it may be washed only with hot water), and it was blown and dried, and then put into a reduction furnace. The reduction temperature was 1000 ° C., the time was 60 s, and the hydrogen gas concentration was 20%. It was cooled to about 460 ° C., charged into a galvanizing pot, and allowed to stay for 3 seconds. Thereby, the hot dip galvanization of zinc was completed and the hot dip galvanization product of about 1.8 mm was obtained.

  The gold phase micrograph of the cross section of the iron oxide skin after the hot-rolled sheet obtained in Example 1 undergoes 50% cold rolling is shown in FIG. Although it began to become discontinuous, it was not clear that the iron oxide peeled off or was pressed into the substrate. The surface morphology photograph of the iron oxide skin is shown in FIG. 3, and the oxide (that is, the iron oxide skin) is distributed in a strip shape along the rolling direction and begins to have a discontinuous distribution. The scanning photograph of the cross section of the galvanized plate obtained in Example 1 is shown in FIG. 4, and the iron oxide skin was almost thoroughly reduced, and the residual iron oxide skin was not clear. FIG. 5 shows a photograph of the surface of the plated layer after the obtained galvanized plate is bent by 180 °. The adhesion of the plated layer is good, and cracks or detachment of the zinc layer was not obvious.

  The slab was heated to 1230 ° C. and allowed to stay in the furnace for 210 minutes. The tapping temperature was 1170 ° C. After descaling with high-pressure water, rough rolling was performed, descaling was again performed with high-pressure water, and finish rolling was performed. The initial temperature of finish rolling is 930 ° C., the final temperature is 850, the winding temperature is 560 ° C., the rolling speed is 12 m / s, and the cooling rate after rolling is 20 ° C./s. . The thickness of the obtained hot-rolled sheet was 3.05 mm, the average thickness of the iron oxide skin on the surface was 7 μm, and among them, the content of triiron tetroxide was at least 65%. An emulsion or pure water was used as the lubricant. The hot-rolled sheet was cold-rolled with an iron oxide skin and cold-rolled to 2.9 mm, and the deformation rate was 5%. After washing with an alkaline solution (when rolling is lubricated with pure water, alkali washing is not necessary, it may be washed only with hot water), and it was blown and dried, and then put into a reduction furnace. The reduction temperature was 800 ° C., the time was 180 s, and the hydrogen gas concentration was 50%. After cooling to about 470 ° C., it was put into a galvanizing pot and allowed to stay for 5 seconds. Thus, zinc-aluminum-magnesium hot-dip plating was completed, and a hot-dip zinc-aluminum-magnesium plating product of about 2.90 mm was obtained. FIG. 6 shows a cross-sectional scan of the resulting zinc-aluminum-magnesium plated plate, where the plating layer is continuous and complete, the iron oxide skin is thoroughly reduced, and its energy spectrum. The analysis is shown in Table 1.

  The slab was heated to 1180 ° C. and allowed to stay in the furnace for 250 minutes. The tapping temperature was 1200 ° C. After descaling with high-pressure water, rough rolling was performed, descaling was again performed with high-pressure water, and finish rolling was performed. The initial temperature of finish rolling is 950 ° C., the final temperature is 800, the winding temperature is 550 ° C., the rolling speed is 10 m / s, and the cooling rate after rolling is 30 ° C./s. . The thickness of the obtained hot-rolled sheet was 4 mm, and the average thickness of the iron oxide skin on the surface was 5 μm. Among them, the content of triiron tetroxide was at least 70%. An emulsion or pure water was used as the lubricant. The hot-rolled sheet was cold-rolled with the iron oxide skin attached, and the deformation rate was 70%. After washing with an alkaline solution (when water is used, alkali washing is not necessary), the mixture was blown dry and then put into a reduction furnace. The reduction temperature was 600 ° C., the time was 300 s, and the hydrogen gas concentration was 20%. After cooling to about 465 ° C., it was put into a galvanizing pot and allowed to stay for 3 seconds. Thereby, hot dip galvanization was completed, and the component of the plating solution was 1.2 Al wt% -Zn, and a hot dip galvanized product of about 2.9 mm was obtained.

  The slab was heated to 1200 ° C. and kept in the furnace for 200 minutes. The tapping temperature was 1250 ° C. After descaling with high-pressure water, rough rolling was performed, descaling was again performed with high-pressure water, and finish rolling was performed. The initial temperature of finish rolling is 980 ° C., the final temperature is 880, the winding temperature is 570 ° C., the rolling speed is 18 m / s, and the cooling rate after rolling is 12 ° C./s. . The thickness of the obtained hot-rolled sheet was 3.6 mm, the average thickness of the iron oxide skin on the surface was 8 μm, among which the content of triiron tetroxide was at least 50%. An emulsion or pure water was used as the lubricant. The hot-rolled sheet was cold-rolled with an iron oxide skin and cold-rolled until the thickness became 1.5 mm, and the deformation rate was 58%. After washing with an alkaline solution (when rolling is lubricated with pure water, alkali washing is not necessary, it may be washed only with hot water), and it was blown and dried, and then put into a reduction furnace. The reduction temperature was 900 ° C., the time was 120 s, and the hydrogen gas concentration was 20%. It was cooled to about 460 ° C., charged into a galvanizing pot, and allowed to stay for 3 seconds. As a result, hot dip galvanization was completed, and a zinc solution component of 1.6 Al wt% -1.6 Mg-Zn% and a hot dip zinc-aluminum-magnesium plating product of about 1.2 mm was obtained.

  The tapping temperature was 1230 ° C., and it stayed in the furnace for 200 minutes. The tapping temperature was 1190 ° C. After descaling with high-pressure water, rough rolling was performed, descaling was again performed with high-pressure water, and finish rolling was performed. The initial temperature of finish rolling is 950 ° C., the final temperature is 900, the winding temperature is 550 ° C., the rolling speed is 21 m / s, and the cooling rate after rolling is 15 ° C./s. . The thickness of the obtained hot-rolled sheet was 3.6 mm, the average thickness of the iron oxide skin on the surface was 8 μm, among which the content of triiron tetroxide was at least 50%. Emulsion or pure water was used as the lubricant. The hot-rolled sheet was cold-rolled with an iron oxide skin and cold-rolled until the thickness became 1.5 mm, and the deformation rate was 58%. After washing with an alkaline solution (when rolling is lubricated with pure water, alkali washing is not necessary, it may be washed only with hot water), and it was blown and dried, and then put into a reduction furnace. The reduction temperature was 900 ° C., the time was 120 s, and the hydrogen gas concentration was 20%. It was cooled to about 680 ° C., charged into a galvanizing pot, and allowed to stay for 3 seconds. A component of the zinc solution was 11 Si wt% -Al%, and a molten aluminum-silicon plating product of about 1.2 mm was obtained.

  It was proved by practice that Examples 2-5, as in Example 1, were successful in obtaining a hot-dip plated product that could meet expectations and that there was no obvious skip plating or plating layer shedding. .

As described above, the present invention controls the structure of the iron oxide skin on the surface of the hot rolled plate by adjusting the hot rolling process, and the iron oxide skin is applied to the hot rolled plate. Cold rolling is applied, and the iron oxide skin is plastically deformed along with the substrate without falling off in the process of cold rolling deformation, so that the reducing gas (CO or H ₂ ) and the iron oxide skin Metallic iron is produced by the reaction, and finally hot dip galvanizing is performed. Compared with the traditional hot dip galvanizing process, the process eliminates the pickling and related steps and does not require the iron oxide skin to be removed by pickling, and is corrosive such as hydrochloric acid and sulfuric acid. Since no medium is used, the problem of environmental pollution caused by pickling can be fundamentally solved, and it is an environmental protection type hot dip galvanizing process that is short in process, efficient, and low in cost, meeting actual demand. It has performance that can be done.

  According to the method of manufacturing a product obtained by hot rolling, direct cold rolling without pickling, reduction annealing, and hot dipping according to the present invention, it is possible to obtain hot-dipped products with different thickness specifications, In particular, a thick hot dip galvanized product can be obtained. In addition, when the obtained product does not have strict requirements on surface quality and there are some requirements on corrosion resistance and mechanical properties, for example, various construction steels, steels for electric power facilities, highways and various bridge guardrails, It is particularly useful in areas such as storage and plant steel.

  The above is only a specific embodiment of the present invention, and the present invention is not limited to the above embodiment, and there are many similar variations based on them. Should. All variants derived or associated directly by the person skilled in the art from the content disclosed in the present invention fall within the protection scope of the present invention. That is, a person skilled in the art can make various changes or modifications to the present invention after reading the above description described in the present invention, and equivalent forms thereof are also claimed in the claims attached to the present application. It should be understood that it falls within the scope limited by the scope.

Claims (13)

A method for producing a product obtained by hot rolling, direct cold rolling without pickling, reduction annealing, and hot dipping,
It was subjected to descaling against the slab, rough rolling by Sonobe mill, finishing finish by mill rolling, cooling by a cooling device, and you sequentially perform the winding by a coiler, hot performed by hot rolling units A rolling step , and in the hot rolling step, the slab tapping temperature is 1100 to 1250 ° C, the final rolling temperature is 800 to 900 ° C, the winding temperature is 550 to 600 ° C, and the rolling speed is 8 to 20 m / s, the cooling rate after rolling is 7 to 30 ° C./s, obtained by hot rolling, direct cold rolling without pickling, reduction annealing, and hot dipping. The manufacturing method of the product
Rolling lubricant is used for rolling, the rolling is completed within 1-2 path, characterized in that the deformation rate of each path is controlled to 1.0% to 90%, row by cold rolling units Cold rolling process,
The introduction to Rukoto a reducing gas, and based on changing the iron oxide skin and then cooled to a temperature at which the strip enters the galvanizing pot, and a reduction annealing process performed by the reducing furnace, the reducing temperature It is 500 to 1000 ° C., the reduction time is 60 to 300 s, the reducing gas is a mixture of H ₂ or CO and an inert gas, and the concentration of H ₂ or CO does not fall below 3%. The method for producing a product obtained by hot rolling, direct cold rolling without pickling, reduction annealing, and hot dipping is further provided.
After the reduction annealing process, it is directly put into a galvanizing pot and retained in a few seconds to complete the hot dipping process. A method for producing a product obtained by cold rolling, reduction annealing, and hot dipping.   After the cold rolling process, the degreasing and rinsing machine further includes a degreasing process that removes oil stains and dust remaining on the surface in the cold rolling process using an alkaline degreasing agent, rinses and dries. The method for producing a product obtained by hot rolling according to claim 1, direct cold rolling without pickling, reduction annealing, and hot dipping. The tapping temperature is 1150 to 1200 ° C., the final rolling temperature is 840 to 870 ° C., the winding temperature is 550 to 570 ° C., the rolling speed is 14 to 18 m / s, and the cooling speed is 15 to The method for producing a product obtained by hot rolling according to claim 1 , direct cold rolling without pickling, reduction annealing, and hot dipping, characterized by being 20 ° C / s. The tapping temperature is 1170 or 1200 ° C., the final rolling temperature is 850 or 860 ° C., the winding temperature is 550 or 560 ° C., the rolling speed is 17 or 18 m / s, and the cooling speed is 19 or The method for producing a product obtained by hot rolling according to claim 1 , direct cold rolling without pickling, reduction annealing, and hot dipping, characterized by being 20 ° C / s. In the hot rolling step, the thickness of the obtained hot rolled sheet is 1.0 to 6 mm, the average thickness of the iron oxide skin on the surface of the hot rolled sheet is 5 to 10 μm, and the structure of the iron oxide skin There was mainly Fe ₃ O ₄ and FeO, therein, Fe ₃ content of O ₄ is equal to or less than 50% by weight, hot-rolling according to claim 1, pickling unwanted direct cold A method for producing a product obtained by hot rolling, reduction annealing, and hot dipping. The hot-rolled and pickling-free according to claim 5 , wherein the hot-rolled sheet has a thickness of 1.5 to ₄ mm, and the Fe ₃ O ₄ content is 65% or more. Of products obtained by direct cold rolling, reduction annealing, and hot dipping. The hot rolling according to claim 1 , direct cold rolling without pickling, reduction annealing, and characterized in that the rolling is completed in one pass and the deformation rate is controlled to 50% to 80%. A method for producing a product obtained by hot dipping. In the cold rolling process, as the rolling lubricant, deionized water or palm oil is used, and wherein the cold rolling reduction rate of 1.0% to 90%, heat of claim 1 A method for producing a product obtained by hot rolling, direct cold rolling without pickling, reduction annealing, and hot dipping. The product obtained by hot rolling according to claim 8 , direct cold rolling without pickling, reduction annealing, and hot dipping, wherein the cold rolling reduction is 50% to 80% Manufacturing method. The hot rolling according to claim 1 , wherein the reduction temperature is 750 to 950 ° C., the residence time is 120 to 300 s, and the concentration of H ₂ or CO is 10% to 75%. A method for producing a product obtained by direct cold rolling, reduction annealing, and hot dipping without pickling. The reduction temperature is 800 ° C., 850 ° C. or 900 ° C., the residence time is 180 s, 240 s or 300 s, and the concentration of H ₂ or CO is 15%, 25% or 30%, Item 2. A method for producing a product obtained by hot rolling according to Item 1 , direct cold rolling without pickling, reduction annealing, and hot dipping. In the reduction annealing step, H ₂ or CO that does not participate in the reaction is cycled, obtained by hot rolling according to claim 1 , direct cold rolling without pickling, reduction annealing, and hot dipping. Manufacturing method for finished products.   The hot-dip galvanized product obtained in the hot-dip plating step includes hot-dip galvanized, hot-dip zinc-aluminum-magnesium plated, hot-dip aluminum-zinc plated or hot-dip aluminum-silicon plated products. Of products obtained by hot rolling, direct cold rolling without pickling, reduction annealing, and hot dipping.