Production method of alloy steel plate with electroslag ingot finished plate thickness of 40 mm and below

Abstract

The invention discloses a production method for an alloy steel plate with the electroslag ingot finished plate thickness of 40 mm or below. The production method comprises the steps of electroslag ingot cleaning process control, heating process control, dephosphorization process control, cogging process control and secondary rolling process control. Wherein in the electroslag ingot cogging process, the electroslag ingot is loaded into a trolley furnace or a bell-type furnace for hydrogen diffusion annealing after cogging, the charging temperature of the cogging blank is larger than or equal to 300 DEG C, the temperature is increased to 600-650 DEG C after steel braising is conducted for 2 hours, heat preservation is conducted for 72 hours, then the temperature is slowly decreased to 200-220 DEG C within 48 hours, the furnace is discharged, the heating and cooling rate is smaller than or equal to 50 DEG C / h, and a furnace door is strictly prohibited to be opened in the cooling process. And after annealing and discharging, directly cutting with temperature, and cleaning the upper and lower surfaces of the blank surface by adopting a temperature flame scaling cleaning mode until the upper and lower surfaces have complete metallic luster without warping. The method is simple in process, low in equipment investment and obvious in effect, the surface of the steel plate basically does not need to be ground in the later period, and the rejection rate is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy, and in particular relates to a method for producing an alloy steel plate having a thickness of 40 mm or less after being formed into an electroslag ingot. Background Art

[0002] In order to develop space technology, occupy the space domain, accelerate the modernization of national defense and strengthen national defense, many countries in the world today, especially developed countries, are willing to spend huge amounts of money and compete to develop and manufacture advanced aviation, aerospace and navigation equipment, such as spacecraft, international space stations, artificial satellites, nuclear submarines, jet long-range bombers, atomic energy, rockets, missiles and other equipment.

[0003] However, these cutting-edge equipment have very strict requirements on the material properties used in their manufacture, and put forward a series of special and strict requirements on the steel, alloys, and blanks used, such as high purity, high uniformity, high temperature resistance, high pressure resistance, impact resistance, and fatigue resistance. In particular, the requirements for the stability, consistency, and reliability of material properties are very high.

[0004] Alloy steel plates produced from electroslag ingots can effectively meet these requirements. Electroslag remelting effectively removes harmful elements and impurities from the alloy, improving the purity of the alloy steel, enhancing ingot crystallization, making the alloy steel's structure more uniform and dense, and enhancing its mechanical properties and corrosion resistance. Furthermore, the process is simple to operate, low cost, and consumes minimal energy, making it suitable for large-scale industrial production.

[0005] Some special equipment requires the use of electroslag ingots to produce steel plates with a thickness of 40 mm or less. During the electroslag remelting process, a large amount of hydrogen will be generated inside the electroslag ingots, which can easily cause defects such as steel plates that fail flaw detection and surface cracks. Conventional production uses electroslag ingots to directly roll steel plates into hot hydrogen annealing. However, the steel plates produced from electroslag ingots with a thickness of less than 40 mm have a small unit weight and a fast temperature drop after rolling, making it difficult to achieve hot hydrogen annealing after rolling, which can easily lead to the hydrogen in the steel being unable to overflow and causing the steel plates to be scrapped. At the same time, the unit weight is small, and small ingots need to be used for production, resulting in a low yield. In response to the above problems, the present invention provides a method for producing high-quality electroslag ingot alloy steel plates with a thickness of 40 mm or less. Summary of the Invention

[0006] The technical problem to be solved by the present invention is a production method for alloy steel plates with good quality and a thickness of 40 mm or less from electroslag ingots; the method provided by the present invention has a simple process, low equipment investment, and obvious effect, and can solve the problems of non-compliance in flaw detection, warping, surface cracks, folding and iron sheets of steel plates with a thickness of 40 mm or less from electroslag ingots. The surface of the steel plates basically does not need to be ground in the later stage, which greatly reduces the scrap rate.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: A method for producing alloy steel plates with a thickness of 40 mm or less from electroslag ingots, comprising the following steps: cleaning the electroslag ingots, heating, dephosphorizing, blanking, and secondary rolling; During the ESR ingot forming process, the ingot is loaded into a trolley furnace or bell-type furnace for hydrogen annealing. The ingot is loaded into the furnace at a temperature ≥ 300°C, simmered for 2 hours, then raised to 600-650°C for holding. The ingot is then slowly cooled to 200-220°C before being removed from the furnace at a heating rate of ≤ 50°C / hour. The furnace door is strictly prohibited from being opened during the cooling process. After annealing, the ingot is directly cut while still hot (cutting temperature ≥ 150°C). The ingot is then cleaned using a hot flame stripping method (cleaning temperature ≥ 120°C) to achieve a full metallic luster and no warping.

[0008] Preferably, in the electroslag ingot cleaning process of the present invention, the cleaning intensity of defects is increased during the cleaning process, the depth-to-width ratio of the cleaning area is ≤0.2, the cleaning area should be smooth without sharp corners, and trenching is strictly prohibited.

[0009] Preferably, in the electroslag ingot heating process of the present invention, the atmosphere in the heating furnace is a non-oxidizing atmosphere, and the micro-positive pressure in the heating furnace is maintained between 0-30Pa. Step-by-step heating is adopted, and the electroslag ingot is charged to a furnace temperature of 300-400°C and kept for 2 hours, then raised to 700°C at a rate of ≤80°C / h and kept warm for 3 hours, then raised to 950°C at a rate of ≤100°C / h and kept warm for 3 hours, and finally raised to 1260-1280°C at a rate of ≤120°C / h and kept warm for 10-18 hours; the heating and holding temperature of the open billet is 1260°C-1280°C, and the time in the furnace is 1-1.2min / mm; the time for the electroslag ingot to be transferred from the furnace to the dephosphorization box is controlled to be ≤2min, and the time for the open billet to be transferred from the furnace to the dephosphorization box is ≤1min.

[0010] Preferably, in the dephosphorization process of the present invention, the high-pressure dephosphorization water pressure is ≥20 MPa, the height of the dephosphorization nozzle is adjusted according to the shape of the electroslag ingot, and the inclination angle of the dephosphorization nozzle is 12-16°.

[0011] Preferably, in the process of opening the blank, the temperature is kept at 600-650°C for 72 hours; and the temperature is lowered to 200-220°C and then taken out of the furnace, which takes 48 hours.

[0012] Preferably, in the secondary rolling process of the electroslag ingot of the present invention, a large reduction is adopted in the rough rolling stage, the average reduction per pass is controlled to be 15-23 mm, the start rolling temperature of the finishing rolling is 910-930°C, and the final rolling temperature is 890-910°C.

[0013] Preferably, the thickness of the alloy steel plate made from the electroslag ingot of the present invention is 8-40 mm.

[0014] The electroslag ingot steel plate with a thickness of 40 mm or less produced by the method of the present invention has good flaw detection and surface quality after rolling, and the flaw detection can meet the NB / T 47013.3-2023 TI level, without problems such as warping, surface cracks, folding and iron scale, and the surface grinding area is ≤0.5m 2 .

[0015] The surface of the product of the present invention is not allowed to have defects such as folds, cracks, bubbles, scars and inclusions. It is required to be delivered without iron sheets, and the grinding area of ​​the steel plate surface is ≤5%.

[0016] The beneficial effects of adopting the above technical solution are: In the electroslag ingot cleaning process of the present invention, the depth-to-width ratio of the cleaning area is controlled to be ≤0.2, which can reduce the generation of surface defects such as cracks and folds during rolling.

[0017] During the heating process of the present invention, the micro-positive pressure in the furnace is controlled to be between 0-30 Pa, thereby reducing the entry of external air, thereby facilitating the maintenance of the furnace temperature and reducing energy consumption.

[0018] The heating process of the present invention sets a suitable heating temperature, adds a temperature gradient, reduces internal stress, heats more evenly, can effectively prevent the generation of deep cracks and is beneficial to plate shape control.

[0019] The dephosphorization process of the present invention is controlled by adjusting the height of the dephosphorization nozzle according to the ingot shape, changing the distance between the dephosphorization nozzle and the ingot surface, and tilting the dephosphorization nozzle at an angle of 12-16 degrees to maximize the dephosphorization effect of the dephosphorization nozzle.

[0020] The blanking process control of the present invention can prepare good blanks for secondary rolling; the blanks are subjected to heated hydrogen expansion annealing, which can effectively allow the hydrogen in the steel to fully overflow and solve the problem that the subsequent hydrogen cannot overflow; the upper and lower surfaces are cleaned to a complete metallic luster and no warping by heated flame peeling cleaning, which can effectively prevent the occurrence of defects such as cracks, folds, and iron sheets in secondary rolling; the appropriate blanking thickness is determined according to the thickness of the finished plate, which can avoid the problem of steel plate warping caused by a large temperature drop when rolling thick blanks into thin plates and a low blank temperature.

[0021] The invention controls the secondary rolling process and the start and finish rolling temperature, which can reduce the generation of iron oxide scale, refine the grains, and improve the performance and shape of the steel plate.

[0022] 7. The method of the present invention has a simple process, low equipment investment and obvious effect. It can solve the problems of non-conformity in flaw detection, warping, surface cracks, folding and iron sheets of steel plates with a thickness of less than 40 mm in electroslag ingots. In the later stage, the surface of the steel plate basically does not need to be ground, which greatly reduces the scrap rate. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below with reference to specific embodiments. Example 1

[0024] In this embodiment, the alloy steel plate made from electroslag ingots has a blanking specification of 120*2450*1550 and a secondary rolling specification of 8*2500*9000mm*2 times the length, and is made from 27.77t electroslag ingots.

[0025] The production method of the electroslag ingot alloy steel plate of this embodiment includes an electroslag ingot cleaning process, a heating process, a dephosphorization process, a cogging process and a secondary rolling process.

[0026] The specific process steps are as follows: (1) Control of the electroslag ingot cleaning process: During the electroslag ingot cleaning process, the surface defects of the ingot depth are cleaned to a qualified standard, the depth-to-width ratio of the defects is 0.15, and the transition area between the cleaned area and the uncleaned area is smooth and has no sharp corners.

[0027] (2) Heating process control: During the heating process of the electroslag ingot, a slight positive pressure of 10Pa is maintained in the heating furnace, no oxygen is detected in the initial section of the flue, and the flue gas volume is sufficient; the electroslag ingot is charged to a furnace temperature of 400℃ for 2 hours, then raised to 700℃ at a rate of ≤80℃ / h and kept warm for 3 hours, then raised to 950℃ at a rate of ≤100℃ / h and kept warm for 3 hours, and finally raised to 1260℃ at a rate of ≤120℃ / h and kept warm for 10 hours; the heating and holding temperature of the open billet is 1260℃, and the time in the furnace is 1.2min / mm; the time for the electroslag ingot to be transferred from the furnace to the dephosphorization box is 1 minute and 20 seconds, and the time for the open billet to be transferred from the furnace to the dephosphorization box is 30 seconds.

[0028] (3) Dephosphorization process control: During the dephosphorization process, the water pressure is 21.5 MPa, the dephosphorization nozzle height is 1000 mm, the distance from the ingot surface is 120 mm, and the dephosphorization nozzle tilt angle is 15°.

[0029] (4) Control of the billeting process: After the electroslag ingot is billeted, it is loaded into a trolley furnace for hydrogen expansion annealing. The billet is loaded into the furnace at a temperature of 320°C. After simmering for 2 hours, the temperature is raised to 600-650°C and kept at this temperature for 72 hours. The temperature is then slowly lowered to 200°C over 48 hours before being taken out of the furnace. The heating and cooling rate is ≤50°C / h. It is strictly forbidden to open the furnace door during the cooling process. After annealing, the billet is directly cut with heat (cutting temperature 190°C). The surface of the billet is cleaned with a hot flame peeling method (cleaning temperature 160°C) to a complete metallic luster and no warping.

[0030] (5) Secondary rolling process control: The average reduction per pass in the rough rolling stage of the steel plate is 15 mm; the starting temperature of the finishing rolling is 915 °C and the final rolling temperature is 895 °C during the steel plate rolling.

[0031] The electroslag ingot alloy steel plate produced in this embodiment has good flaw detection, surface quality and flatness, and can meet the NB / T 47013.3-2023 TI grade. The product surface is free of defects such as cracks, folds, bubbles, scars and inclusions. The surface does not need to be ground after rolling, and delivery without iron sheet can be achieved. Example 2

[0032] In this embodiment, the alloy steel plate made from electroslag ingots has a blanking specification of 160*2450*2850 and a secondary rolling specification of 16*2500*12000mm*2 times the length, and is made from 29.27t electroslag ingots.

[0033] The production method of the electroslag ingot alloy steel plate of this embodiment includes an electroslag ingot cleaning process, a heating process, a dephosphorization process, a cogging process and a secondary rolling process.

[0034] The specific process steps are as follows: (1) Control of the electroslag ingot cleaning process: During the electroslag ingot cleaning process, the surface defects of the ingot depth are cleaned to a qualified standard, the depth-to-width ratio of the defects is 0.2, and the transition area between the cleaned area and the uncleaned area is smooth and has no sharp corners.

[0035] (2) Heating process control: During the heating process of the electroslag ingot, a slight positive pressure of 7Pa is maintained in the heating furnace, no oxygen is detected in the initial section of the flue, and the flue gas volume is sufficient; the electroslag ingot is charged to a furnace temperature of 350℃ for 2 hours, then raised to 700℃ at a rate of ≤80℃ / h and kept warm for 3 hours, then raised to 950℃ at a rate of ≤100℃ / h and kept warm for 3 hours, and finally raised to 1265℃ at a rate of ≤120℃ / h and kept warm for 12 hours; the heating and holding temperature of the open billet is 1270℃, and the time in the furnace is 1.1min / mm; the time for the electroslag ingot to be transferred from the furnace to the dephosphorization box is 1 minute and 30 seconds, and the time for the open billet to be transferred from the furnace to the dephosphorization box is 35 seconds.

[0036] (3) Dephosphorization process control: During the dephosphorization process, the water pressure is 21 MPa, the dephosphorization nozzle height is 1000 mm, the distance from the ingot surface is 120 mm, and the dephosphorization nozzle tilt angle is 16°.

[0037] (4) Control of the billeting process: After the electroslag ingot is billeted, it is loaded into a trolley furnace for hydrogen annealing. The billet is loaded into the furnace at a temperature of 330°C. After simmering for 2 hours, the temperature is raised to 600-650°C and kept at this temperature for 72 hours. The billet is then slowly cooled to 200°C over 48 hours and taken out of the furnace. The heating and cooling rate is ≤50°C / h. It is strictly forbidden to open the furnace door during the cooling process. After annealing, the billet is directly cut with heat (cutting temperature 180°C). The billet surface is cleaned with a hot flame peeling method (cleaning temperature 150°C) on both the upper and lower surfaces until it is completely metallic and shiny without warping.

[0038] (5) Secondary rolling process control: The average reduction per pass in the rough rolling stage of the steel plate is 17 mm; the starting temperature of the finishing rolling is 910 °C and the final rolling temperature is 890 °C during the rolling of the steel plate.

[0039] The electroslag ingot alloy steel plate produced in this embodiment has good flaw detection, surface quality and flatness, and can meet the NB / T 47013.3-2023 TI level. There are no defects such as cracks, folds, bubbles, scars and inclusions on the surface of the product. The surface grinding area after rolling is 0.2m 2 , which can realize delivery without iron sheet. Example 3

[0040] In this embodiment, the alloy steel plate made from electroslag ingots has a blanking specification of 200*2100*4050 and a secondary rolling specification of 32*2000*11300mm*2 times the length, and is made from 34.71t electroslag ingots.

[0041] The production method of the electroslag ingot alloy steel plate of this embodiment includes an electroslag ingot cleaning process, a heating process, a dephosphorization process, a cogging process and a secondary rolling process.

[0042] The specific process steps are as follows: (1) Control of the electroslag ingot cleaning process: During the electroslag ingot cleaning process, the surface defects of the ingot depth are cleaned to a qualified standard, the depth-to-width ratio of the defects is 0.17, and the transition area between the cleaned area and the uncleaned area is smooth and has no sharp corners.

[0043] (2) Heating process control: During the heating process of the electroslag ingot, a slight positive pressure of 30Pa is maintained in the heating furnace, no oxygen is detected in the initial section of the flue, and the flue gas volume is sufficient; the electroslag ingot is charged to a furnace temperature of 320℃ for 2 hours, then raised to 700℃ at a rate of ≤80℃ / h and kept warm for 3 hours, then raised to 950℃ at a rate of ≤100℃ / h and kept warm for 3 hours, and finally raised to 1270℃ at a rate of ≤120℃ / h and kept warm for 15 hours; the heating and holding temperature of the open billet is 1275℃, and the time in the furnace is 1.1min / mm; the time for the electroslag ingot to be transferred from the furnace to the dephosphorization box is 1 minute and 15 seconds, and the time for the open billet to be transferred from the furnace to the dephosphorization box is 40 seconds.

[0044] (3) Dephosphorization process control: During the dephosphorization process, the water pressure is 22 MPa, the dephosphorization nozzle height is 1100 mm, the distance from the ingot surface is 130 mm, and the dephosphorization nozzle tilt angle is 14°; (4) Control of the billeting process: After the electroslag ingot is billeted, it is loaded into a trolley furnace for hydrogen annealing. The billet is loaded into the furnace at a temperature of 330°C. After simmering for 2 hours, the temperature is raised to 600-650°C and kept at this temperature for 72 hours. The billet is then slowly cooled to 210°C over 48 hours and then removed from the furnace. The heating and cooling rate is ≤50°C / h. The furnace door is strictly prohibited from being opened during the cooling process. After annealing, the billet is directly cut with heat (cutting temperature 185°C). The billet surface is cleaned with a hot flame peeling method (cleaning temperature 160°C) to a complete metallic luster and no warping.

[0045] (5) Secondary rolling process control: The average reduction per pass in the rough rolling stage of the steel plate is 20 mm, the finishing rolling start temperature is 925 °C, and the final rolling temperature is 905 °C.

[0046] The electroslag ingot alloy steel plate produced in this embodiment has good flaw detection, surface quality and flatness, and can meet the NB / T 47013.3-2023 TI level. There are no defects such as cracks, folds, bubbles, scars and inclusions on the surface of the product. The surface grinding area after rolling is 0.23m 2 , which can realize delivery without iron sheet. Example 4

[0047] In this embodiment, the alloy steel plate made from electroslag ingots has a blanking specification of 260*2200*3900 and a secondary rolling specification of 40*2300*10300mm*2 times the length, and is made from 37.52t electroslag ingots.

[0048] The production method of the electroslag ingot alloy steel plate of this embodiment includes an electroslag ingot cleaning process, a heating process, a dephosphorization process, a cogging process and a secondary rolling process.

[0049] The specific process steps are as follows: (1) Control of the electroslag ingot cleaning process: During the electroslag ingot cleaning process, the surface defects of the ingot depth are cleaned to a qualified standard, the depth-to-width ratio of the defects is 0.18, and the transition area between the cleaned area and the uncleaned area is smooth and has no sharp corners.

[0050] (2) Heating process control: During the heating process of the electroslag ingot, a slight positive pressure of 20Pa is maintained in the heating furnace, no oxygen is detected in the initial section of the flue, and the flue gas volume is sufficient; the electroslag ingot is charged to a furnace temperature of 300℃ for 2 hours, then raised to 700℃ at a rate of ≤80℃ / h and kept warm for 3 hours, then raised to 950℃ at a rate of ≤100℃ / h and kept warm for 3 hours, and finally raised to 1280℃ at a rate of ≤120℃ / h and kept warm for 18 hours; the heating and holding temperature of the open billet is 1280℃, and the time in the furnace is 1min / mm; the time for the electroslag ingot to be transferred from the furnace to the dephosphorization box is 1 minute and 50 seconds, and the time for the open billet to be transferred from the furnace to the dephosphorization box is 45 seconds.

[0051] (3) Dephosphorization process control: During the dephosphorization process, the water pressure is 20.5 MPa, the dephosphorization nozzle height is 1050 mm, the distance from the ingot surface is 110 mm, and the dephosphorization nozzle tilt angle is 12°.

[0052] (4) Control of the billeting process: After the electroslag ingot is billeted, it is loaded into a trolley furnace for hydrogen annealing. The billet is loaded into the furnace at a temperature of 340°C. After simmering for 2 hours, the temperature is raised to 600-650°C and kept at this temperature for 72 hours. The temperature is then slowly lowered to 220°C over 48 hours and taken out of the furnace. The heating and cooling rate is ≤50°C / h. It is strictly forbidden to open the furnace door during the cooling process. After annealing, it is directly cut with heat (cutting temperature 195°C). The surface of the billet is cleaned with a hot flame peeling method (cleaning temperature 165°C) to a complete metallic luster and no warping.

[0053] (5) Secondary rolling process control: The average reduction per pass in the rough rolling stage of the steel plate is 23 mm, the starting temperature of the finishing rolling is 930 °C, and the final rolling temperature is 910 °C.

[0054] The electroslag ingot alloy steel plate produced in this embodiment has good flaw detection, surface quality and flatness, and can meet the NB / T 47013.3-2023 TI level. There are no defects such as cracks, folds, bubbles, scars and inclusions on the surface of the product. The surface grinding area after rolling is 0.25m 2 , which can realize delivery without iron sheet.

[0055] Comparative Example 1 The alloy steel plate made from electroslag ingots in this comparative example has a blanking specification of 120*2450*1550 and a secondary rolling specification of 8*2500*9000mm*2 times the length, and is made from 27.77t electroslag ingots.

[0056] The production method of the electroslag ingot alloy steel plate of this comparative example includes an electroslag ingot cleaning process, a heating process, a dephosphorization process, a cogging process and a secondary rolling process.

[0057] The specific process steps are as follows: (1) Control of the electroslag ingot cleaning process: During the electroslag ingot cleaning process, the surface defects of the ingot depth are cleaned to a qualified standard, the depth-to-width ratio of the defects is 0.15, and the transition area between the cleaned area and the uncleaned area is smooth and has no sharp corners.

[0058] (2) Heating process control: During the heating process of the electroslag ingot, a slight positive pressure of 10Pa is maintained in the heating furnace, no oxygen is detected in the initial section of the flue, and the flue gas volume is sufficient; the electroslag ingot is charged to a furnace temperature of 400℃ for 2 hours, then raised to 700℃ at a rate of ≤80℃ / h and kept warm for 3 hours, then raised to 950℃ at a rate of ≤100℃ / h and kept warm for 3 hours, and finally raised to 1270℃ at a rate of ≤120℃ / h and kept warm for 10 hours; the heating and holding temperature of the open billet is 1260℃, and the time in the furnace is 1.2min / mm; the time for the electroslag ingot to be transferred from the furnace to the dephosphorization box is 1 minute and 20 seconds, and the time for the open billet to be transferred from the furnace to the dephosphorization box is 30 seconds.

[0059] (3) Dephosphorization process control: During the dephosphorization process, the water pressure is 21.5 MPa, the dephosphorization nozzle height is 1000 mm, the distance from the ingot surface is 120 mm, and the dephosphorization nozzle tilt angle is 15°.

[0060] (4) Control of the billeting process: After the electroslag ingot is billeted, it is loaded into a trolley furnace for hydrogen expansion annealing. The billet is loaded into the furnace at a temperature of 80°C. After simmering for 2 hours, the temperature is raised to 600-650°C and kept at this temperature for 72 hours. The temperature is then slowly lowered to 200°C over 48 hours before being taken out of the furnace. The heating and cooling rate is ≤50°C / h. The furnace door is strictly prohibited from being opened during the cooling process. After annealing, the billet is directly cut with heat (cutting temperature 190°C). The surface of the billet is cleaned with a hot flame peeling method (cleaning temperature 160°C) to a complete metallic luster and no warping.

[0061] (5) Secondary rolling process control: The average reduction per pass in the rough rolling stage of the steel plate is 20 mm; the starting temperature of the finishing rolling is 915 °C and the final rolling temperature is 895 °C during the rolling of the steel plate.

[0062] The electroslag ingot alloy steel plate produced in this comparative example does not meet the NB / T 47013.3-2023 TI grade during flaw detection. The product surface does not have defects such as cracks, folds, bubbles, scars and inclusions. The surface does not need to be ground after rolling, and can be delivered without iron scale.

[0063] The difference between this comparative example and Example 1 is that: The charging temperature of the billet is 80℃, which is too low, causing the hydrogen in the steel to be unable to escape. The flaw detection does not meet the NB / T 47013.3-2023 TI grade. Although the surface quality and flatness of the steel plate are good, the steel plate cannot meet the use requirements.

[0064] Comparative Example 2 The alloy steel plate made from electroslag ingots in this comparative example has a blanking specification of 160*2450*2850 and a secondary rolling specification of 16*2500*12000mm*2 times the length, and is made from 29.27t electroslag ingots.

[0065] The production method of the electroslag ingot alloy steel plate of this comparative example includes an electroslag ingot cleaning process, a heating process, a dephosphorization process, a cogging process and a secondary rolling process.

[0066] The specific process steps are as follows: (1) Control of the electroslag ingot cleaning process: During the electroslag ingot cleaning process, the surface defects of the ingot depth are cleaned to a qualified standard, the depth-to-width ratio of the defects is 0.2, and the transition area between the cleaned area and the uncleaned area is smooth and has no sharp corners.

[0067] (2) Heating process control: During the heating process of the electroslag ingot, a slight positive pressure of 7Pa is maintained in the heating furnace, no oxygen is detected in the initial section of the flue, and the flue gas volume is sufficient; the electroslag ingot is charged to a furnace temperature of 95℃ for 2 hours, then heated to 700℃ at a rate of ≤80℃ / h and kept warm for 3 hours, then heated to 950℃ at a rate of ≤100℃ / h and kept warm for 3 hours, and finally heated to 1265℃ at a rate of ≤120℃ / h and kept warm for 12 hours; the heating and holding temperature of the open billet is 1270℃, and the time in the furnace is 1.1min / mm; the time for the electroslag ingot to be transferred from the furnace to the dephosphorization box is 1 minute and 30 seconds, and the time for the open billet to be transferred from the furnace to the dephosphorization box is 35 seconds.

[0068] (3) Dephosphorization process control: During the dephosphorization process, the water pressure is 21 MPa, the dephosphorization nozzle height is 1000 mm, the distance from the ingot surface is 120 mm, and the dephosphorization nozzle tilt angle is 16°.

[0069] (4) Control of the billeting process: After the electroslag ingot is billeted, it is loaded into a trolley furnace for hydrogen annealing. The billet is loaded into the furnace at a temperature of 330°C. After simmering for 2 hours, the temperature is raised to 600-650°C and kept at this temperature for 72 hours. The billet is then slowly cooled to 200°C over 48 hours and taken out of the furnace. The heating and cooling rate is ≤50°C / h. It is strictly forbidden to open the furnace door during the cooling process. After annealing, the billet is directly cut with heat (cutting temperature 180°C). The billet surface is cleaned with a hot flame peeling method (cleaning temperature 150°C) on both the upper and lower surfaces until it is completely metallic and shiny without warping.

[0070] (5) Secondary rolling process control: The average reduction per pass in the rough rolling stage of the steel plate is 17 mm; the starting temperature of the finishing rolling is 910 °C and the final rolling temperature is 890 °C during the rolling of the steel plate.

[0071] The difference between this comparative example and Example 2 is that: The charging temperature of the electroslag ingot is 95℃. The temperature is too low, and internal stress is generated inside the electroslag ingot, which is eventually released and extends to the surface, resulting in large-area cracks on the surface of the billet. The cleaning volume is large, resulting in the billet being too thin, and the steel plate size cannot meet the use requirements.

[0072] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been 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 producing alloy steel plates with a thickness of 40 mm or less from electroslag ingots, characterized in that: It includes the following processes: electroslag ingot cleaning, heating, dephosphorization, blanking and secondary rolling; The electroslag ingot blanking process comprises the following steps: after the electroslag ingot is blanked, it is loaded into a trolley furnace or a bell-type furnace for hydrogen expansion annealing; the blank loading temperature is ≥300°C; after simmering for 2 hours, the temperature is raised to 600-650°C for insulation; the temperature is then lowered to 200-220°C before being taken out of the furnace; the heating and cooling rate is ≤50°C / h; and it is strictly forbidden to open the furnace door during the cooling process; after annealing and being taken out of the furnace, the blank is directly cut with a temperature ≥150°C; the blank surface is cleaned by a hot flame peeling method with a cleaning temperature ≥120°C; the upper and lower surfaces are cleaned until they have complete metallic luster and no warping.

2. The method for producing an electroslag ingot alloy steel plate with a thickness of 40 mm or less according to claim 1, characterized in that: In the electroslag ingot cleaning process, the depth-to-width ratio of the cleaning area is ≤0.

2.

3. The method for producing an electroslag ingot alloy steel plate with a thickness of 40 mm or less according to claim 1, characterized in that: During the electroslag ingot heating process, the atmosphere in the heating furnace is a non-oxidizing atmosphere, and the slightly positive pressure in the heating furnace is controlled between 0-30Pa.

4. A method for producing an alloy steel plate with a thickness of 40 mm or less as a result of electroslag ingot production according to claim 1 or 3, characterized in that: The electroslag ingot heating process adopts step-by-step heating, the electroslag ingot is charged to a furnace temperature of 300-400°C for 2 hours, then raised to 700°C at a rate of ≤80°C / h and kept for 3 hours, then raised to 950°C at a rate of ≤100°C / h and kept for 3 hours, and finally raised to 1260-1280°C at a rate of ≤120°C / h and kept for 10-18 hours; The heating and holding temperature of the open billet is 1260℃-1280℃, and the time in the furnace is 1-1.2min / mm; the time for transferring the electroslag ingot from the furnace to the dephosphorization box is controlled to be ≤2min, and the time for transferring the open billet from the furnace to the dephosphorization box is ≤1min.

5. The method for producing an electroslag ingot alloy steel plate with a thickness of 40 mm or less according to claim 1, characterized in that: In the electroslag ingot dephosphorization process, the high-pressure dephosphorization water pressure is ≥20 MPa, and the dephosphorization nozzle inclination angle is 12-16°.

6. The method for producing alloy steel plates with a thickness of 40 mm or less from electroslag ingots according to claim 1, characterized in that: The process of opening the blank is to keep the temperature at 600-650°C for 72 hours; and to cool the temperature to 200-220°C and take the blank out of the oven for 48 hours.

7. The method for producing an electroslag ingot alloy steel plate with a thickness of 40 mm or less according to claim 1, characterized in that: In the secondary rolling process of the electroslag ingot, a large reduction is adopted in the rough rolling stage, the average reduction per pass is controlled to be 15-22 mm, the start rolling temperature of the finishing rolling is 900-920° C., and the final rolling temperature is 880-900° C.

8. The method for producing alloy steel plates with a thickness of 40 mm or less from electroslag ingots according to claim 1, characterized in that: The thickness of the alloy steel plate made from the electroslag ingot is 8-40 mm.

9. The method for producing alloy steel plates with a thickness of 40 mm or less from electroslag ingots according to claim 1, characterized in that: The surface grinding area of ​​the electroslag ingot plate produced by the method is ≤0.5m 2 .