Method for solving bending problem of small square billet

Abstract

The invention relates to a method for solving bending of a small square billet, and belongs to the technical field of alloy steel smelting and continuous casting methods. According to the technical scheme, casting blanks are densely arranged on a stepping steel turnover cooling bed, and steel turnover operation is continuously conducted; after the casting blanks are discharged from the cooling bed, the adze blanks are hoisted from a collecting rack of the cooling bed and stored in a blank stack area, and slow cooling is conducted in a close-packed stacking mode. The method has the beneficial effects that the equipment investment and maintenance cost are saved, the production cost is reduced, the air-cooling bending degree of the casting blank is effectively controlled, the requirements of the steel rolling heating furnace are met, the casting blank can smoothly enter the steel rolling heating furnace, the process is simple and reliable, and the problem that the casting blank cannot enter the steel rolling heating furnace after being offline in the production process is solved. And the quality defect that the bending degree of the casting blank exceeds the standard easily occurs in the stacking and cooling process, and the quality loss is reduced.

Description

Technical Field

[0001] The invention relates to a method for solving the bending of a small square billet, and belongs to the technical field of alloy steel smelting and continuous casting methods. Background Art

[0002] In the production of small square billets, the bending of continuous casting billets is mainly caused by the difference in linear expansion coefficients of different metallographic structures. The bending of the billet can be controlled by controlling the cooling rate and the final metallographic structure.

[0003] During the production process, the secondary cooling of the continuous casting machine is controlled to improve the cooling uniformity of the ingot, control the residence time of the continuous casting ingot on the roller table, increase the strength value of the continuous casting ingot when it is placed on the cooling bed, optimize the cooling bed turning operation, etc., to reduce the bending of the continuous casting ingot on the line.

[0004] During the production process, the continuous casting billet is prone to quality defects such as excessive curvature of the billet during the process of coming off the line and cooling. Severely exceeding the standard will cause the billet to be unable to push the steel into the heating furnace normally and can only be scrapped, causing serious quality losses and increased costs.

[0005] Most enterprises produce small square billets and medium carbon chromium-molybdenum alloy steel. They use heat preservation pits or slow cooling pits to slow cool the billets after they come off the production line to prevent the billets from bending beyond the standard. Therefore, heat preservation pits or slow cooling pits must be available. Summary of the invention

[0006] The purpose of the present invention is to provide a method for solving the bending of small square billets. By adopting a close-packed stacking method for slow cooling, the bending degree of the billet can be reduced without adding any equipment, thereby saving equipment investment and maintenance costs, and reducing production costs. The air-cooling curvature of the billet is effectively controlled, the curvature of the billet is not more than 10 mm per meter, and the total curvature of the billet is not more than 0.5% of the total length, which meets the requirements of the steel rolling heating furnace and can smoothly enter the steel rolling heating furnace. The process is simple and reliable, and the quality defect of the billet curvature exceeding the standard during the stacking cooling process after the billet is off the line in the production process is solved, which reduces quality losses and effectively solves the above-mentioned problems existing in the background technology.

[0007] The technical solution of the present invention is: a method for solving the bending of small square billets, comprising the following steps: (1) The ingots are rolled off the production line and are densely arranged on the step-by-step steel turning cooling bed, and the steel turning operation is performed continuously; (2) Slow cooling of the ingot. After the ingot comes down from the cooling bed, it is hoisted from the cooling bed collecting stand and stored in the ingot stacking area, where it is slowly cooled by close stacking; (3) After slow cooling, the ingots are shipped.

[0008] The step (1) also includes a marking process, in which after the ingots arrive at the cooling bed collecting stand, the cross-section of one end of the ingots is sprayed with numbers one by one, and the spray numbers include the internal code of the steel grade and the furnace number information.

[0009] In the step (2), the close-packed stacking method is that the bottom of the stack uses hot billets of other steel types with the same length and cross-section produced in the previous casting as the bottom billet of the stack, and a layer of bottom billet is laid, with 6-12 hanging bottom billets placed on each side of each layer, medium-carbon chromium-molybdenum alloy steel small square billets in the middle, and a layer of bottom billets placed on the top.

[0010] In the step (2), the slow cooling time is ≥ 7 days, and the ingot is cooled to below 80°C.

[0011] In the step (2), each layer of the ingot must be densely packed.

[0012] In the step (1), the ingots are taken off the production line using an overhead crane with an electromagnetic crane to facilitate close arrangement of the ingots.

[0013] The ingot is a medium carbon chromium-molybdenum alloy steel billet, with a curvature of ≤10 mm per meter and a total curvature of no more than 0.5% of the total length.

[0014] The ingot is a medium carbon chromium-molybdenum alloy steel square billet with a cross-section of 150 mm*150 mm and a fixed length of 12 meters.

[0015] The beneficial effects of the present invention are as follows: by adopting a close-packed stacking method for slow cooling, the curvature of the ingot can be reduced without adding any equipment, thereby saving equipment investment and maintenance costs, and reducing production costs. The curvature of the ingot during air cooling is effectively controlled, the curvature of the ingot is not more than 10 mm per meter, and the total curvature of the ingot is not more than 0.5% of the total length, which meets the requirements of the steel rolling heating furnace and can smoothly enter the steel rolling heating furnace. The process is simple and reliable, and the quality defect of excessive curvature of the ingot that is prone to occur during the stacking cooling process after the ingot is off the line in the production process is solved, thereby reducing quality losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the close arrangement of the carbon-chromium-molybdenum alloy steel ingot of the present invention; In the figure: medium carbon chromium-molybdenum alloy steel ingot 1, other steel grade hot ingot 2. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the invention implementation cases clearer, the technical solutions in the implementation cases of the present invention will be clearly and completely described below in conjunction with the drawings in the implementation cases. Obviously, the implementation cases described are only a small part of the implementation cases of the present invention, rather than all the implementation cases. Based on the implementation cases in the present invention, all other implementation cases obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0018] A method for solving the bending of a small square billet comprises the following steps: (1) The ingots are rolled off the production line and are densely arranged on the step-by-step steel turning cooling bed, and the steel turning operation is performed continuously; (2) Slow cooling of the ingot. After the ingot comes down from the cooling bed, it is hoisted from the cooling bed collecting stand and stored in the ingot stacking area, where it is slowly cooled by close stacking; (3) After slow cooling, the ingots are shipped.

[0019] The step (1) also includes a marking process, in which after the ingots arrive at the cooling bed collecting stand, the cross-section of one end of the ingots is sprayed with numbers one by one, and the spray numbers include the internal code of the steel grade and the furnace number information.

[0020] In the step (2), the close-packed stacking method is that the bottom of the stack uses hot billets of other steel types with the same length and cross-section produced in the previous casting as the bottom billet of the stack, and a layer of bottom billet is laid, with 6-12 hanging bottom billets placed on each side of each layer, medium-carbon chromium-molybdenum alloy steel small square billets in the middle, and a layer of bottom billets placed on the top.

[0021] In the step (2), the slow cooling time is ≥ 7 days, and the ingot is cooled to below 80°C.

[0022] In the step (2), each layer of the ingot must be densely packed.

[0023] In the step (1), the ingots are taken off the production line using an overhead crane with an electromagnetic crane to facilitate close arrangement of the ingots.

[0024] The ingot is a medium carbon chromium-molybdenum alloy steel billet, with a curvature of ≤10 mm per meter and a total curvature of no more than 0.5% of the total length.

[0025] The ingot is a medium carbon chromium-molybdenum alloy steel square billet with a cross-section of 150 mm*150 mm and a fixed length of 12 meters. Example

[0026] Taking the production of SCM435 steel by an 8-machine 8-strand 150mm×150mm small square billet continuous casting machine as an example, the billet output of a single furnace is about 140 tons, and the fixed length of the continuous casting billet is 12 meters.

[0027] The chemical composition requirements of SCM435 steel are shown in the following table:

[0028] Before producing the steel grade SCM435, the continuous casting machine arranged to produce a casting of SWRCH8A with a total of 12 furnaces, and the ingots were placed in the B10 stack (stack number: B10), and the last 5 furnaces were planned to be used to enclose SCM435. The last furnace of SWRCH8A ingots were placed in the B20 stack (stack number: B20) where SCM435 ingots will be stored in the future, and the stack bottom was laid.

[0029] Before the SCM435 ingots come off the production line, the operator uses a high-temperature wax pen to mark "O" on the unsprayed end of the SWRCH8A ingots used for the bottom of the stack. In this way, both ends of the ingots used for the bottom of the stack are marked to prevent mixing of steel.

[0030] The steel grade SCM435 is produced, and 6 furnaces are planned to be produced. The method for controlling the bending of the ingot includes the process of ingot off-line and slow cooling of the ingot. The specific process steps are as follows: (1) Billet off-line process: The billets are densely packed on the cooling bed and continuously turned over. After reaching the collection stand, the billets are numbered one by one on the cross section at one end of the billet. The number contains the internal code of the steel grade and the furnace number information.

[0031] (2) Billet stacking process: Use a 50-ton electromagnetic overhead crane to lift the billets from the cooling bed collection rack and store them on the B20 stack with a stack bottom.

[0032] (3) The specific implementation details of the B20 stacking position are as follows: The first layer: Use the last furnace SWRCH8A, 68 ingots to lay the bottom of the stack.

[0033] The second layer: The second layer of billets is stacked vertically relative to the first layer of billets. The overhead crane lifts 10 marked SWRCH8A billets from the B10 stack and places them vertically on one end of the bottom billet (the first layer). Then the overhead crane places 55 SCM435 billets off the line closely together with the SWRCH8A billets. When there are about 2 meters left in this layer, the overhead crane sucks 8 marked SWRCH8A billets from the B10 stack and places them at the end of this layer closely together with the SCM435 billets.

[0034] Layer 3: The stacking method of the third layer is similar to that of the second layer. The third layer of ingots is stacked vertically relative to the second layer of ingots. The overhead crane lifts 7 marked SWRCH8A ingots from the B10 stacking position and places them at the beginning of this layer. Then the overhead crane places 53 SCM435 ingots off the line closely with the SWRCH8A ingots. When there are about 2 meters left in this layer, the overhead crane sucks 12 marked SWRCH8A ingots from the B10 stacking position and places them at the end of this layer closely with the SCM435 ingots.

[0035] Layer 4: The 4th layer of ingots is stacked vertically relative to the 3rd layer of ingots. The overhead crane lifts 6 marked SWRCH8A ingots from the B10 stack and places them at the beginning of this layer. Then the overhead crane places 56 SCM435 ingots off the line closely with the SWRCH8A ingots. When there are about 2 meters left in this layer, the overhead crane sucks 10 marked SWRCH8A ingots from the B10 stack and places them at the end of this layer closely with the SCM435 ingots.

[0036] Layer 5: The 5th layer of ingots are stacked vertically relative to the 4th layer. The overhead crane lifts 8 marked SWRCH8A ingots from the B10 stack and places them at the beginning of this layer. Then the overhead crane places 55 SCM435 ingots off the line closely with the SWRCH8A ingots. When there are about 2 meters left in this layer, the overhead crane sucks 8 marked SWRCH8A ingots from the B10 stack and places them at the end of this layer closely with the SCM435 ingots.

[0037] Layer 6: The 6th layer of ingots is stacked vertically relative to the 5th layer of ingots. The overhead crane lifts 7 marked SWRCH8A ingots from the B10 stack and places them at the beginning of this layer. Then the overhead crane places 56 SCM435 ingots off the line closely with the SWRCH8A ingots. When there are about 2 meters left in this layer, the overhead crane sucks 11 marked SWRCH8A ingots from the B10 stack and places them at the end of this layer closely with the SCM435 ingots.

[0038] Layer 7: The 7th layer of ingots is stacked vertically relative to the 6th layer of ingots. The overhead crane lifts 8 marked SWRCH8A ingots from the B10 stack and places them at the beginning of this layer. Then the overhead crane places 53 SCM435 ingots off the line closely with the SWRCH8A ingots. When there are about 2 meters left in this layer, the overhead crane sucks 10 marked SWRCH8A ingots from the B10 stack and places them at the end of this layer closely with the SCM435 ingots.

[0039] Layer 8: The 8th layer of ingots are stacked vertically relative to the 7th layer. The overhead crane lifts 9 marked SWRCH8A ingots from the B10 stack and places them at the beginning of this layer. Then the overhead crane places 52 SCM435 ingots off the line closely with the SWRCH8A ingots. When there are about 2 meters left in this layer, the overhead crane sucks 11 marked SWRCH8A ingots from the B10 stack and places them at the end of this layer closely with the SCM435 ingots.

[0040] The 9th layer of ingots is stacked vertically relative to the 8th layer of ingots. The overhead crane lifts 10 marked SWRCH8A ingots from the B10 stack and places them at the beginning of this layer. Then the overhead crane places the last 40 SCM435 ingots of this pouring closely together with the SWRCH8A ingots. Then the overhead crane sucks two hangings of 23 marked SWRCH8A ingots from the B10 stack and places them closely together with the SCM435 ingots.

[0041] On the 10th layer, perpendicular to the direction of the 9th layer of ingots, the overhead crane sucks 72 marked SWRCH8A ingots from the B10 stack and presses them closely on the 9th layer.

[0042] The surface temperature of the SCM435 steel billet during stacking is measured as follows:

[0043] After 7 days of slow cooling, the ingots were shipped. When the ingots were shipped, their curvature was tested. The curvature was 0-10mm per meter and the curvature of the whole ingot was 5-60mm, which fully met the requirement of the steel rolling heating furnace for a total curvature of ≤90mm.

[0044] The present invention reduces the curvature of the billet without adding any equipment, saves equipment investment and maintenance costs, and reduces production costs. The air-cooled curvature of the carbon-chromium-molybdenum alloy steel continuous casting billet in the production of small square billets is effectively controlled, the curvature of the billet is no more than 10 mm per meter, and the total curvature of the billet is no more than 0.5% of the total length, which meets the requirements of the steel rolling heating furnace and can smoothly enter the steel rolling heating furnace. The process is simple and reliable. The problem of excessive curvature of the billet that is prone to occur during the stacking cooling process after the billet is off the production line in the production process is solved, and quality loss is reduced.

[0045] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for solving the bending of small square billets, characterized in that The following steps are involved: The ingots are rolled off the production line and are densely arranged on the step-by-step steel turning cooling bed, with continuous steel turning operations. Slow cooling of the ingot. After the ingot comes down from the cooling bed, it is hoisted from the cooling bed collecting stand and stored in the ingot stacking area, where it is slowly cooled by close stacking. After slow cooling, the ingots are shipped.

2. A method for solving the bending of small square billets according to claim 1, characterized in that: The step (1) also includes a marking process, in which after the ingots arrive at the cooling bed collecting stand, the cross-section of one end of the ingots is sprayed with numbers one by one, and the spray numbers include the internal code of the steel grade and the furnace number information.

3. A method for solving the bending of small square billets according to claim 1, characterized in that: In the step (2), the close-packed stacking method is that the bottom of the stack uses hot billets of other steel types with the same fixed length and cross-section produced in the previous casting as the bottom billet of the stack, and a layer of bottom billet is laid, with 6-12 hanging bottom billets placed on each side of each layer, and small square billets of medium-carbon chromium-molybdenum alloy steel in the middle, and a layer of bottom billets is placed on the top layer.

4. A method for solving the bending of small square billets according to claim 1, characterized in that: In the step (2), the slow cooling time is ≥ 7 days, and the ingot is cooled to below 80°C.

5. A method for solving the bending of small square billets according to claim 1, characterized in that: In the step (2), each layer of the ingot must be densely packed.

6. A method for solving the bending of small square billets according to claim 1, characterized in that: In the step (1), the ingots are taken off the production line using an overhead crane with an electromagnetic crane to facilitate close arrangement of the ingots.

7. A method for solving the bending of billets according to claim 1, characterized in that: The ingot is a medium carbon chromium-molybdenum alloy steel billet, with a curvature of ≤10 mm per meter and a total curvature of no more than 0.5% of the total length.

8. A method for solving the bending of billets according to claim 1, characterized in that: The ingot is a medium carbon chromium-molybdenum alloy steel square billet with a cross-section of 150 mm*150 mm and a fixed length of 12 meters.

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