CN111074049B - Production process for reducing surface cracks of chromium-molybdenum alloy steel plate with high chromium content - Google Patents

Production process for reducing surface cracks of chromium-molybdenum alloy steel plate with high chromium content Download PDF

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CN111074049B
CN111074049B CN201911161145.9A CN201911161145A CN111074049B CN 111074049 B CN111074049 B CN 111074049B CN 201911161145 A CN201911161145 A CN 201911161145A CN 111074049 B CN111074049 B CN 111074049B
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temperature
blank
furnace
cogging
steel plate
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CN111074049A (en
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邓建军
赵国昌
高雅
刘彦强
顾自有
石天柱
曾小峰
霍圆圆
齐燕
吉大地
张伟
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Wuyang Iron and Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/52—Manufacture of steel in electric furnaces
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0006—Adding metallic additives
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/076—Use of slags or fluxes as treating agents
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Abstract

A process for reducing the surface cracks of the Cr-Mo alloy steel plate with high Cr content includes smelting, pouring, annealing steel ingot, cogging and cutting steel ingot, primary annealing of cogging material, cleaning cogging material, secondary annealing of cogging material and rolling. The invention eliminates the risk of cracks on the surface of the rolled steel plate from the source through the control of the steel ingot smelting and casting process; the carbon arc air gouging is adopted to clean the micro-crack defects generated on the surface of the blank, so that the problem that the defects are difficult to remove by traditional flame cleaning is solved; the blank heating and rolling process is controlled, and the potential adverse factors of surface cracks are reduced. The method can reduce the phenomenon of cracks on the surface of the steel plate, reduce the probability of waste products of the steel plate due to the cracks on the surface, has good benefit, and is suitable for producing the high-strength chromium-molybdenum alloy steel plate with the thickness of 12-30 mm, the carbon content of 0.1-0.13%, the molybdenum content of 0.9-1.1% and the chromium content of 8-10% for power equipment and pipe fittings in the petrochemical industry.

Description

Production process for reducing surface cracks of chromium-molybdenum alloy steel plate with high chromium content
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a production process for reducing surface cracks of a chromium-molybdenum alloy steel plate with high chromium content.
Background
The chromium-molybdenum alloy steel has excellent high-temperature strength and creep resistance, the corrosion resistance and the oxidation resistance of the chromium-molybdenum alloy steel are obviously higher than those of alloy steels of other grades, the chromium-molybdenum alloy steel is applied to the manufacturing of power equipment and pipe fittings in the petrochemical industry, boiler and pipe parts can be effectively reduced, the thermal fatigue resistance of equipment can be improved, compared with other austenite section steels, the chromium-molybdenum alloy steel has better heat conductivity and lower expansion rate, can be widely applied to superheater and reheater pipes in a power plant boiler, is also used for a header and a steam pipe under the condition of high-temperature steam, and is also applied to heating furnace pipes in the petrochemical industry.
Because the chromium-molybdenum alloy steel plate has high chromium and molybdenum alloy element content, the chromium element content reaches 9 percent, the continuous casting billet finished product mode production is difficult to realize, the main reason is that the casting billet quality control technical requirement is high, and the realization of batch production does not have a mature process. Therefore, the steel plate is produced by adopting a steel ingot cogging and forming mode, but cracks are easily generated on the surface in the steel plate production process, so that a set of complete production process flow is developed as a main research direction for key procedures such as steel ingot casting, blank crack cleaning, heating rolling and the like, and the method has important significance for reducing the generation of cracks on the surface of the steel plate.
Disclosure of Invention
The invention aims to solve the technical problem of providing a production process for reducing surface cracks of a chromium-molybdenum alloy steel plate with high chromium content.
In order to solve the technical problems, the invention adopts the technical scheme that: a production process for reducing surface cracks of a chromium-molybdenum alloy steel plate with high chromium content comprises the working procedures of smelting, pouring, steel ingot annealing, steel ingot cogging and cutting, cogging stock primary annealing, cogging stock cleaning, cogging stock secondary annealing and cogging stock rolling; in the casting process, the casting ladle temperature is 1545-1565 ℃, the casting temperature is controlled at 1520-1545 ℃, 3-4 kg of Al-RE alloy rare earth modifier per ton of steel is added into the molten steel before casting, a coarse second phase in the alloy is refined, and the tendency of generating hot cracks on the surface of a steel ingot can be reduced; in the cogging stock rolling procedure, a roller cooling water system is closed in the cogging stock heating and rolling process, a temperature-increasing rolling mode is adopted, the cogging temperature is 1050-1100 ℃, the finish rolling temperature is controlled to be not less than 950 ℃, the surface cracking of the steel plate caused by local supercooling of the steel plate is avoided, the stacking is slowly cooled after rolling, the stacking temperature is more than 500 ℃, and the stacking time is 48-72 hours.
In the smelting process, the P is removed at low temperature in the oxygen melting period of electric furnace steelmaking, the ladle temperature is more than 1600 ℃, and slag-free tapping is carried out; the white slag retention time in the refining process is more than or equal to 30min, the vacuum degree in the vacuum treatment process is less than or equal to 55Pa, the vacuum retention time is more than or equal to 30min, and harmful elements are controlled at the smelting end point: p is less than or equal to 0.006 percent, S is less than or equal to 0.006 percent, Sb is less than or equal to 0.003 percent, Sn is less than or equal to 0.005 percent, and As is less than or equal to 0.012 percent.
According to the steel ingot annealing process, a steel ingot is placed into a soaking pit furnace for annealing, the thermal stress and the structural stress of the steel ingot are eliminated, cracks are prevented from being generated on the surface and the inside of the steel ingot, the heating speed is controlled, the temperature of the steel ingot is increased to 900-950 ℃ after 20-24 hours of feeding, the heat preservation time is 48-60 hours, the cooling process is gentle, the cooling time is controlled to 22-24 hours, and the steel ingot is discharged from the furnace after being cooled to 250-300 ℃ for cogging rolling.
According to the steel ingot cogging and cutting process, a soaking furnace is adopted for heating the steel ingot, the steel ingot is loaded at the furnace temperature of less than or equal to 700 ℃, the temperature is raised after being loaded for 2-4 hours at the temperature raising speed of less than or equal to 75 ℃/h, the temperature is raised to 900-920 ℃, the temperature is kept for 6-8 hours, then the temperature is raised to 1230-1250 ℃ at the temperature raising speed of less than or equal to 75 ℃/h, the temperature is kept for 15-20 hours, the steel ingot is taken out of the furnace for cogging, high-pressure water is started for descaling in the rolling process, the water pressure is controlled to be 18-22 MPa, and the included angle between a water nozzle and the steel ingot is 70-80 degrees; the thickness of the blank is controlled to be 140-200 mm, the cap opening of the blank is cut off after the blank is opened, the blank is cut to a proper length according to the size of a steel plate finished product, the surface temperature of the blank is controlled to be more than or equal to 250 ℃ during cutting, and cracks are prevented from being generated after cutting.
According to the blank opening one-time annealing process, in order to eliminate residual stress in the rolled blank and reduce the surface hardness of the blank, the surface of the blank is convenient to carry out peeling cleaning subsequently, cracks are avoided in the surface cleaning process, the surface temperature of the blank is controlled to be not less than 200 ℃ before the blank is placed into a furnace for annealing, the furnace temperature is not more than 200 ℃, the temperature of the blank is raised to 650-700 ℃ after the blank is placed into the furnace, the heat preservation is started, the temperature raising time is more than 24 hours, the heat preservation time is 48-60 hours, the temperature is lowered to 200-250 ℃ after the heat preservation is finished, the blank is taken out of the furnace, the surface of the blank is peeled and cleaned, and the temperature reduction time is kept at 24-36 hours.
According to the cogging stock cleaning process, due to the fact that the alloy content is high, thermal stress cracks are easily generated on the surface of a cogging blank, a metal thin layer on the surface of a billet cannot be melted to remove micro cracks existing on the surface by traditional flame cleaning, the surface crack defects are removed by adopting a carbon arc gouging mode, the diameter of a used carbon rod is 6-8 mm, and the proper gouging width is guaranteed; the polarity working mode of the power supply is direct current reverse connection, the blank is connected with the negative electrode, the carbon rod is connected with the positive electrode, and the electric arc is ensured to work stably without fluctuation; the current is selected in proportion to the diameter of the carbon rod, the current is controlled to be 285-345A, and the voltage is 40-42V; in order to ensure the size, the surface quality and the stability of the planing process of the planing groove, the planing speed is controlled to be 0.6-1.5 m/min, the compressed air pressure is controlled to be 0.5-0.6 MPa, the extending length of the carbon rod is controlled to be 85-100 mm, and when the burning loss of the carbon rod is reduced to 25-30 mm continuously, the extending length of the carbon rod is adjusted to be 85-100 mm again; in order to obtain proper planing groove depth and planing speed, the included angle between the carbon rod and the surface of the blank is 45-60 degrees, the arc length is controlled to be 1-2 mm, and uniform planing size is guaranteed.
According to the blank opening secondary annealing process, the temperature difference between a blank cleaning part and an uncleaned part is large in the air gouging cleaning process, in order to avoid the situation that cracks are easily generated on the cleaned part, the cleaned blank is annealed, the blank after air gouging cleaning is put into a furnace and heated to 300-350 ℃ at the heating rate of 40-60 ℃/h, the temperature is kept for 3-4 h, then the temperature is continuously heated to 650-700 ℃, the temperature is kept for 48-60 h, the blank is cooled to 200-250 ℃ after the temperature is kept, and is taken out of the furnace for rolling, and the temperature is kept for more than 24 h.
The RE content of the Al-RE alloy rare earth alterant is 1.5-2%, and the balance is Al.
The production process is suitable for producing the high-strength chromium-molybdenum alloy steel plate for the power equipment and the petrochemical industry pipe fittings, which has the thickness of 12-30 mm, the carbon content of 0.1-0.13%, the molybdenum content of 0.9-1.1% and the chromium content of 8-10%.
The production process effectively reduces cracks on the surface of the steel plate, the one-time inspection qualification rate of the steel plate is kept above 96%, and the mechanical property qualification rate of the steel plate reaches 98%.
The beneficial effect that adopts above-mentioned technical scheme to produce lies in: 1. the invention improves the surface quality of the steel plate by reducing the content of harmful elements in the smelting process and controlling the ladle temperature, the white slag refining retention time and the vacuumizing time. 2. In the casting process, the proper casting temperature is controlled, and a proper amount of proper modifier is added to reduce the thermal crack tendency of the surface of the steel ingot and avoid cracks on the surface of the rolled steel plate. 3. The steel ingot is transferred into the slow cooling pit for annealing after cogging, so that the residual stress in the ingot can be effectively eliminated, the surface hardness can be reduced, and the crack defect caused by later-stage surface cleaning can be avoided. 4. The cogging material is cleaned of surface defects by adopting the carbon arc gouging, the problem that high-chromium steel is difficult to clean by utilizing flame is solved, and the surface crack defects of the blank are effectively cleaned by controlling the carbon arc gouging cleaning process parameters. 5. According to the invention, cracks on the surface of the blank can be effectively restrained by adopting a secondary annealing process after the blank is opened and air gouged, the cooling water of the roller is closed in the rolling process, cracks caused by local supercooling of the steel plate are avoided, stacking and slow cooling after rolling ensure that the steel plate is slowly cooled at a low speed, and cracks caused by too fast cooling are avoided. 6. The method solves the problem that the surface of the high-chromium-molybdenum alloy steel blank is difficult to clean, effectively reduces the probability of surface crack defects of the steel plate after the blank is rolled, improves the one-time inspection qualified rate of the steel plate, and obtains good economic benefit. 7. The production process is suitable for producing the high-strength chromium-molybdenum alloy steel plate with the thickness of 12-30 mm and the chromium content of 8-10% for the power equipment and the petrochemical industry pipe fittings.
Drawings
FIG. 1 is a metallographic structure of a chrome molybdenum alloy steel plate with high chromium content according to example 1;
FIG. 2 is a surface quality chart of a chromium molybdenum alloy steel plate with a high chromium content in example 1.
Detailed Description
The invention is described in further detail below with reference to the figures and specific examples.
Example 1
The specification of the chromium molybdenum alloy steel plate SA387MGr9Cl1 with high chromium content of the embodiment is 23mm 3030mm 9870mm, C: 0.13%, Mo: 0.98%, Cr: 8.0%, the production process of reducing the surface cracks of the chromium-molybdenum alloy steel plate with high chromium content comprises the working procedures of smelting, pouring, steel ingot annealing, steel ingot cogging and cutting, cogging material primary annealing, cogging material cleaning, cogging material secondary annealing and cogging material rolling, and the specific process steps are as follows:
(1) smelting: carrying out low-temperature P removal in the oxygen melting period of electric furnace steelmaking, wherein the ladle temperature is 1655 ℃, and slag-free tapping is carried out; the white slag retention time in the refining process is 40min, the vacuum degree in the vacuum treatment process is 50Pa, the vacuum retention time is 35min, and harmful elements are controlled at the smelting end point: p: 0.006%, S: 0.002%, Sb: 0.003%, Sn: 0.003%, As: 0.001 percent;
(2) a casting process: the temperature of the casting ladle is 1560 ℃, the casting temperature is 1540 ℃, 3.2 kg of Al-RE alloy rare earth modifier per t of steel is added into the molten steel before casting, the RE content of the Al-RE alloy rare earth modifier is 1.7%, and the balance is Al;
(3) annealing the steel ingot: putting the steel ingot into a soaking pit furnace for annealing, heating the steel ingot into the furnace for 22 hours to 905 ℃, keeping the temperature for 52 hours, cooling the steel ingot for 24 hours, cooling the steel ingot to 300 ℃, discharging the steel ingot out of the furnace and cogging and rolling the steel ingot;
(4) steel ingot cogging and cutting procedures: heating the steel ingot by using a soaking pit furnace, loading the steel ingot at the furnace temperature of 680 ℃, heating the steel ingot for 3h after loading, wherein the heating speed is 70 ℃/h, heating the steel ingot to 900 ℃, preserving heat for 7h, heating the steel ingot to 1245 ℃ according to the heating speed of 70 ℃/h, preserving heat for 19.5h, discharging the steel ingot from the furnace, rolling and cogging the steel ingot, starting high-pressure water to remove scale in the rolling process, controlling the water pressure to be 20MPa, controlling the included angle between a water nozzle and the steel ingot to be 74 degrees, controlling the thickness of the steel ingot to be 140mm, controlling the specification of the steel ingot to be 140 x 2350 x 2480mm, cutting off a cap opening of the steel ingot after cogging, and controlling the surface temperature of the steel ingot to be 250 ℃ during cutting;
(5) a blank opening primary annealing process: controlling the surface temperature of the blank to be 230 ℃ before the blank is placed into a furnace for annealing, controlling the furnace temperature to be 120 ℃, raising the temperature of the blank to 680 ℃ after the blank is placed into the furnace, starting heat preservation, raising the temperature for 30 hours, keeping the temperature for 55 hours, reducing the temperature to 250 ℃ after the heat preservation, discharging the blank from the furnace, peeling and cleaning the surface of the blank, and reducing the temperature for 26 hours;
(6) blank cleaning procedure: removing surface crack defects by adopting a carbon arc gouging mode, wherein the diameter of a used carbon rod is 8 mm; the polarity working mode of the power supply is direct current reverse connection, the blank is connected with the negative electrode, and the carbon rod is connected with the positive electrode; the current is selected to be in direct proportion to the diameter of the carbon rod, the current is 320A, and the voltage is 40.5V; the planing speed is 0.85m/min, the pressure of compressed air is 0.5MPa, the extending length of the carbon rod is 90mm, when the burning loss of the carbon rod is reduced to 28mm continuously, the extending length of the carbon rod is adjusted to 90mm again, the included angle between the carbon rod and the surface of the blank is 55 degrees, and the arc length is 2 mm;
(7) and (3) blank opening secondary annealing process: after the air gouging is cleaned, the blank is put into a furnace, heated to 345 ℃ at the heating rate of 50 ℃/h, kept warm for 3.5h, then continuously heated to 690 ℃, kept warm for 48h, cooled to 250 ℃ after heat preservation, taken out of the furnace, heated and rolled, and cooled for 30 h;
(8) and (3) blank opening rolling procedure: and closing a roller cooling water system in the blank starting heating rolling process, adopting a temperature-increasing rolling mode, controlling the initial rolling temperature to be 1060 ℃, controlling the final rolling temperature to be 970 ℃, slowly cooling the rolled stack at the stacking temperature of 510 ℃, and keeping the stacking time to be 61 h.
The finished steel plate of the embodiment is comprehensively inspected, no crack is formed on the surface of the steel plate, metallographic microstructure observation is immediately carried out, no micro crack is formed on the surface of the steel plate, the cracks on the surface of the steel plate are effectively controlled through the control measures of the production process of the embodiment, the one-time inspection qualified rate of the steel plate is 100%, and the mechanical property qualified rate of the steel plate is 99%.
The metallographic structure of the chromium-molybdenum alloy steel plate with high chromium content in the embodiment is shown in figure 1, and the surface quality diagram is shown in figure 2. (examples 2 to 8 high chromium content chromium molybdenum alloy steel plate metallographic structure diagram is similar to that of FIG. 1, and surface quality diagram is similar to that of FIG. 2, so that it is omitted.)
Example 2
The specification of the chromium molybdenum alloy steel plate SA387MGr9Cl1 with high chromium content of the embodiment is 23mm 2850mm 9240mm, C: 0.11%, Mo: 1.05%, Cr: 9.5%, the production process of reducing the surface cracks of the chromium-molybdenum alloy steel plate with high chromium content comprises the working procedures of smelting, pouring, steel ingot annealing, steel ingot cogging and cutting, cogging material primary annealing, cogging material cleaning, cogging material secondary annealing and cogging material rolling, and the specific process steps are as follows:
(1) smelting: carrying out low-temperature P removal in the oxygen melting period of electric furnace steelmaking, wherein the ladle temperature is 1655 ℃, and slag-free tapping is carried out; the white slag retention time in the refining process is 40min, the vacuum degree in the vacuum treatment process is 50Pa, the vacuum retention time is 35min, and harmful elements are controlled at the smelting end point: p: 0.005%, S: 0.002%, Sb: 0.003%, Sn: 0.003%, As: 0.001 percent;
(2) a casting process: the temperature of the casting ladle is 1560 ℃, the casting temperature is 1535 ℃, 4 kg of Al-RE alloy rare earth modifier per t of steel is added into the molten steel before casting, the RE content of the Al-RE alloy rare earth modifier is 1.6%, and the balance is Al; the unit weight of the obtained steel ingot is 21 t;
(3) annealing the steel ingot: putting the steel ingot into a soaking pit furnace for annealing, heating the steel ingot into the furnace for 24 hours to 950 ℃, keeping the temperature for 52 hours, cooling the steel ingot for 24 hours, cooling the steel ingot to 250 ℃, discharging the steel ingot out of the furnace and cogging and rolling the steel ingot;
(4) steel ingot cogging and cutting procedures: heating a steel ingot by using a soaking pit furnace, loading the steel ingot at the furnace temperature of 680 ℃, heating the steel ingot for 4 hours after loading, wherein the heating speed is 70 ℃/h, heating to 920 ℃, keeping the temperature for 7 hours, heating to 1230 ℃ according to the heating speed of 70 ℃/h, keeping the temperature for 18 hours, discharging from the furnace, rolling and cogging, starting high-pressure water to remove scales in the rolling process, controlling the water pressure to be 18MPa, enabling the included angle between a water nozzle and the steel billet to be 76 degrees, enabling the thickness of the blank to be 140mm, enabling the specification of the blank to be 140mm, 2360mm and 2500mm, cutting off caps of the blank after cogging, and enabling the surface temperature of the blank to be 250 ℃ during cutting;
(5) a blank opening primary annealing process: the surface temperature of the blank is 220 ℃ before the blank is placed into a furnace for annealing, the furnace temperature is 180 ℃, the temperature of the blank is raised to 655 ℃ after the blank is placed into the furnace, the heat preservation is started, the temperature raising time is 28 hours, the heat preservation time is 48 hours, the temperature is reduced to 240 ℃ after the heat preservation is finished, the blank is taken out of the furnace, the surface of the blank is scalped and cleaned, and the temperature reduction time is 28 hours;
(6) blank cleaning procedure: removing surface crack defects by adopting a carbon arc gouging mode, wherein the diameter of a used carbon rod is 8 mm; the polarity working mode of the power supply is direct current reverse connection, the blank is connected with the negative electrode, and the carbon rod is connected with the positive electrode; the current is selected to be in direct proportion to the diameter of the carbon rod, the current is 320A, and the voltage is 40V; the planing speed is 0.85m/min, the pressure of compressed air is 0.5MPa, the extending length of the carbon rod is 90mm, when the burning loss of the carbon rod is reduced to 28mm continuously, the extending length of the carbon rod is adjusted to 90mm again, the included angle between the carbon rod and the surface of the blank is 55 degrees, and the arc length is 2 mm;
(7) and (3) blank opening secondary annealing process: after the air gouging is cleaned, the blank is put into a furnace, heated to 330 ℃ at the heating rate of 45 ℃/h, kept warm for 3.7h, then continuously heated to 680 ℃, kept warm for 50h, cooled to 200 ℃ after heat preservation, taken out of the furnace, heated and rolled, and cooled for 33 h;
(8) and (3) blank opening rolling procedure: and closing a roller cooling water system in the blank starting heating and rolling process, adopting a temperature-increasing rolling mode, controlling the starting rolling temperature to be 1100 ℃, controlling the finishing rolling temperature to be 960 ℃, slowly cooling the rolled stack, and keeping the stacking temperature to be 530 ℃ for 70 h.
The finished steel plate of the embodiment is comprehensively inspected, no crack is formed on the surface of the steel plate, metallographic microstructure observation is immediately carried out, no micro crack is formed on the surface of the steel plate, the cracks on the surface of the steel plate are effectively controlled through the control measures of the production process of the embodiment, the one-time inspection qualification rate of the steel plate is 98%, and the mechanical property qualification rate of the steel plate is 99%.
Example 3
The specification of the chromium molybdenum alloy steel plate SA387MGr9Cl1 with high chromium content of the embodiment is 30mm 2480mm 1200mm, C: 0.13%, Mo: 0.99%, Cr: 9.7%, the production process of reducing the surface cracks of the chromium-molybdenum alloy steel plate with high chromium content comprises the working procedures of smelting, pouring, steel ingot annealing, steel ingot cogging and cutting, cogging material primary annealing, cogging material cleaning, cogging material secondary annealing and cogging material rolling, and the specific process steps are as follows:
(1) smelting: removing P at low temperature in the oxygen melting period of electric furnace steelmaking, wherein the ladle temperature is 1660 ℃, and tapping without slag; the white slag retention time in the refining process is 40min, the vacuum degree in the vacuum treatment process is 43Pa, the vacuum retention time is 34min, and harmful elements are controlled at the smelting end point: p: 0.004%, S: 0.003%, Sb: 0.001%, Sn: 0.003%, As: 0.002%;
(2) a casting process: the temperature of the casting ladle is 1565 ℃, the casting temperature is 1535 ℃, 3.1 kg of Al-RE alloy rare earth modifier per t of steel is added into the molten steel before casting, the RE content of the Al-RE alloy rare earth modifier is 1.5%, and the balance is Al; the unit weight of the obtained steel ingot is 21 t;
(3) annealing the steel ingot: putting the steel ingot into a soaking pit furnace for annealing, heating the steel ingot into the furnace to 900 ℃ after 20 hours, keeping the temperature for 60 hours, cooling the steel ingot for 24 hours, cooling the steel ingot to 270 ℃, discharging the steel ingot out of the furnace and cogging and rolling the steel ingot;
(4) steel ingot cogging and cutting procedures: heating the steel ingot by using a soaking pit furnace, loading the steel ingot at the furnace temperature of 670 ℃, heating the steel ingot for 3h after loading, wherein the heating speed is 60 ℃/h, heating the steel ingot to 910 ℃, preserving the heat for 8h, heating the steel ingot to 1235 ℃ according to the heating speed of 60 ℃/h, preserving the heat for 19h, then discharging the steel ingot from the furnace, rolling and cogging the steel ingot, starting high-pressure water to remove scale in the rolling process, controlling the water pressure to be 21MPa, enabling the water nozzle to form an angle of 72 degrees with the steel ingot, enabling the thickness of the steel ingot to be 140mm, enabling the specification of the steel ingot to be 140mm, 2320mm and 3000mm, cutting off a cap opening of the steel ingot after cogging, and enabling the surface temperature of the steel ingot to be 260 ℃ during cutting;
(5) a blank opening primary annealing process: the surface temperature of the blank is 230 ℃ before the blank is placed into a furnace for annealing, the furnace temperature is 190 ℃, the temperature of the blank is raised to 650 ℃ after the blank is placed into the furnace, the heat preservation is started, the temperature raising time is 30 hours, the heat preservation time is 55 hours, the temperature is reduced to 200 ℃ after the heat preservation is finished, the blank is taken out of the furnace, the surface of the blank is scalped and cleaned, and the temperature reduction time is 34 hours;
(6) blank cleaning procedure: removing surface crack defects by adopting a carbon arc gouging mode, wherein the diameter of a used carbon rod is 6 mm; the polarity working mode of the power supply is direct current reverse connection, the blank is connected with the negative electrode, and the carbon rod is connected with the positive electrode; the current is selected in proportion to the diameter of the carbon rod, the current is 290A, and the voltage is 42V; the planing speed is 1.10m/min, the pressure of compressed air is 0.55MPa, the extending length of the carbon rod is 90mm, when the burning loss of the carbon rod is reduced to 25mm continuously, the extending length of the carbon rod is adjusted to 96mm again, the included angle between the carbon rod and the blank surface is 50 degrees, and the arc length is 1.4 mm;
(7) and (3) blank opening secondary annealing process: after the air gouging is cleaned, the blank is put into a furnace, heated to 340 ℃ at a heating rate of 50 ℃/h, kept warm for 3h, then continuously heated to 680 ℃, kept warm for 52h, cooled to 240 ℃ after heat preservation, taken out of the furnace and rolled, and cooled for 30 h;
(8) and (3) blank opening rolling procedure: and closing a roller cooling water system in the blank starting heating and rolling process, adopting a temperature-raising rolling mode, controlling the starting rolling temperature to be 1090 ℃, controlling the final rolling temperature to be 950 ℃, and slowly cooling the rolled stack at the stacking temperature of 520 ℃ for 60 hours.
The finished steel plate of the embodiment is comprehensively inspected, no crack is formed on the surface of the steel plate, metallographic microstructure observation is immediately carried out, no micro crack is formed on the surface of the steel plate, the cracks on the surface of the steel plate are effectively controlled through the control measures of the production process of the embodiment, the one-time inspection qualification rate of the steel plate is 96%, and the mechanical property qualification rate of the steel plate is 98%.
Example 4
The specification of the chromium-molybdenum alloy steel plate SA387MGr9Cl1 with high chromium content of the embodiment is 23mm 3000mm 9580mm, C: 0.12%, Mo: 1.02%, Cr: 9.4%, the production process of reducing the surface cracks of the chromium-molybdenum alloy steel plate with high chromium content comprises the working procedures of smelting, pouring, steel ingot annealing, steel ingot cogging and cutting, cogging material primary annealing, cogging material cleaning, cogging material secondary annealing and cogging material rolling, and the specific process steps are as follows:
(1) smelting: carrying out low-temperature P removal in the oxygen melting period of electric furnace steelmaking, wherein the ladle temperature is 1655 ℃, and slag-free tapping is carried out; the white slag retention time in the refining process is 35min, the vacuum degree in the vacuum treatment process is 50Pa, the vacuum retention time is 42min, and harmful elements are controlled at the smelting end point: p: 0.003%, S: 0.002%, Sb: 0.002%, Sn: 0.004%, As: 0.003%;
(2) a casting process: the casting ladle temperature is 1545 ℃, the casting temperature is 1520 ℃, 4 kg of Al-RE alloy rare earth modifier per ton of steel is added into the molten steel before casting, the RE content of the Al-RE alloy rare earth modifier is 1.9%, and the balance is Al; the unit weight of the obtained steel ingot is 25 t;
(3) annealing the steel ingot: putting the steel ingot into a soaking pit furnace for annealing, heating the steel ingot to 920 ℃ after the steel ingot is put into the furnace for 23 hours, preserving the heat for 50 hours, cooling for 24.5 hours, cooling to 270 ℃, discharging the steel ingot out of the furnace, and heating, cogging and rolling the steel ingot;
(4) steel ingot cogging and cutting procedures: heating the steel ingot by using a soaking pit furnace, loading the steel ingot at the furnace temperature of 600 ℃, heating for 4h after loading, heating at the heating speed of 55 ℃/h, heating to 905 ℃, keeping the temperature for 7h, heating to 1245 ℃ according to the heating speed of 60 ℃/h, keeping the temperature for 20h, discharging from the furnace, rolling and cogging, starting high-pressure water to remove scale in the rolling process, controlling the water pressure to be 18.5MPa, enabling the water nozzle to form an angle of 79 degrees with the steel billet, enabling the thickness of the billet to be 200mm, enabling the specification of the billet to be 140mm x 2300mm 2600mm, cutting off a cap opening of the billet after cogging, and enabling the surface temperature of the billet during cutting to be 265 ℃;
(5) a blank opening primary annealing process: the surface temperature of the blank is 260 ℃ before the blank is placed into a furnace for annealing, the furnace temperature is 150 ℃, the temperature of the blank is raised to 650 ℃ after the blank is placed into the furnace, the heat preservation is started, the temperature raising time is 30 hours, the heat preservation time is 52 hours, the temperature is reduced to 210 ℃ after the heat preservation is finished, the blank is taken out of the furnace, the surface of the blank is scalped and cleaned, and the temperature reduction time is 36 hours;
(6) blank cleaning procedure: removing surface crack defects by adopting a carbon arc gouging mode, wherein the diameter of a used carbon rod is 8 mm; the polarity working mode of the power supply is direct current reverse connection, the blank is connected with the negative electrode, and the carbon rod is connected with the positive electrode; the current is selected to be in direct proportion to the diameter of the carbon rod, the current is 305A, and the voltage is 41.7V; the planing speed is 1.00m/min, the compressed air pressure is 0.58MPa, the extending length of the carbon rod is 93mm, when the burning loss of the carbon rod is reduced to 29mm continuously, the extending length of the carbon rod is adjusted to 93mm again, the included angle between the carbon rod and the blank surface is 48 degrees, and the arc length is 1.3 mm;
(7) and (3) blank opening secondary annealing process: after the air gouging is cleaned, the blank is put into a furnace, heated to 350 ℃ at the heating rate of 45 ℃/h, kept warm for 3h, then continuously heated to 660 ℃, kept warm for 54h, cooled to 250 ℃ after the heat preservation, taken out of the furnace, heated and rolled, and cooled for 29 h;
(8) and (3) blank opening rolling procedure: and closing a roller cooling water system in the blank starting heating and rolling process, adopting a temperature-raising rolling mode, controlling the initial rolling temperature to be 1080 ℃, controlling the final rolling temperature to be 960 ℃, slowly cooling the rolled stack at the stacking temperature of 550 ℃, and keeping the stacking time to be 65 h.
The finished steel plate of the embodiment is comprehensively inspected, no crack is formed on the surface of the steel plate, metallographic microstructure observation is immediately carried out, no micro crack is formed on the surface of the steel plate, the cracks on the surface of the steel plate are effectively controlled through the control measures of the production process of the embodiment, the one-time inspection qualified rate of the steel plate is 100%, and the mechanical property qualified rate of the steel plate is 100%.
Example 5
The specification of the chromium molybdenum alloy steel plate SA387MGr9Cl1 with high chromium content of the embodiment is 23mm 2950mm 9850mm, C: 0.13%, Mo: 0.95%, Cr: 9.6%, the production process of reducing the surface cracks of the chromium-molybdenum alloy steel plate with high chromium content comprises the working procedures of smelting, pouring, steel ingot annealing, steel ingot cogging and cutting, cogging material primary annealing, cogging material cleaning, cogging material secondary annealing and cogging material rolling, and the specific process steps are as follows:
(1) smelting: removing P at low temperature in the oxygen melting period of electric furnace steelmaking, wherein the ladle temperature is 1635 ℃, and tapping without slag; the white slag retention time in the refining process is 38min, the vacuum degree in the vacuum treatment process is 40Pa, the vacuum retention time is 37min, and harmful elements are controlled at the smelting end point: p: 0.004%, S: 0.006%, Sb: 0.002%, Sn: 0.002%, As: 0.007%;
(2) a casting process: the casting ladle temperature is 1552 ℃, the casting temperature is 1525 ℃, 3.3 kg of Al-RE alloy rare earth modifier per t of steel is added into the molten steel before casting, the RE content of the Al-RE alloy rare earth modifier is 1.7%, and the balance is Al; the unit weight of the obtained steel ingot is 21 t;
(3) annealing the steel ingot: putting the steel ingot into a soaking pit furnace for annealing, heating the steel ingot into the furnace for 24 hours to 940 ℃, keeping the temperature for 55 hours, cooling the steel ingot for 23 hours, cooling the steel ingot to 270 ℃, discharging the steel ingot out of the furnace, and heating, cogging and rolling the steel ingot;
(4) steel ingot cogging and cutting procedures: heating the steel ingot by using a soaking pit furnace, loading the steel ingot at the furnace temperature of 690 ℃, heating the steel ingot for 3.5h after loading, wherein the heating speed is 65 ℃/h, heating the steel ingot to 901 ℃, keeping the temperature for 8h, heating the steel ingot to 1230 ℃ according to the heating speed of 65 ℃/h, keeping the temperature for 20h, discharging the steel ingot out of the furnace, rolling and cogging the steel ingot, starting high-pressure water to remove scales in the rolling process, controlling the water pressure to be 19MPa, enabling the water nozzle to form an angle of 73 degrees with the steel ingot, enabling the thickness of the steel ingot to be 140mm, enabling the specification of the steel ingot to be 140mm, 2450mm and 2590mm, cutting off a cap opening of the steel ingot after cogging, and enabling the surface temperature of the steel ingot to be 270 ℃;
(5) a blank opening primary annealing process: the surface temperature of the blank is 220 ℃ before the blank is placed into a furnace for annealing, the furnace temperature is 150 ℃, the temperature of the blank is raised to 700 ℃ after the blank is placed into the furnace, the heat preservation is started, the temperature raising time is 28 hours, the heat preservation time is 58 hours, the temperature is reduced to 230 ℃ after the heat preservation is finished, the blank is taken out of the furnace, the surface of the blank is scalped and cleaned, and the temperature reduction time is 28 hours;
(6) blank cleaning procedure: removing surface crack defects by adopting a carbon arc gouging mode, wherein the diameter of a used carbon rod is 7 mm; the polarity working mode of the power supply is direct current reverse connection, the blank is connected with the negative electrode, and the carbon rod is connected with the positive electrode; the current is selected to be in direct proportion to the diameter of the carbon rod, the current is 335A, and the voltage is 40V; the planing speed is 1.40m/min, the pressure of compressed air is 0.55MPa, the extending length of the carbon rod is 88mm, when the burning loss of the carbon rod is reduced to 27mm continuously, the extending length of the carbon rod is adjusted to 88mm again, the included angle between the carbon rod and the surface of the blank is 57 degrees, and the arc length is 1.7 mm;
(7) and (3) blank opening secondary annealing process: after the air gouging is cleaned, the blank is put into a furnace, heated to 340 ℃ at the heating rate of 45 ℃/h, kept warm for 4h, then continuously heated to 685 ℃, kept warm for 60h, cooled to 200 ℃ after heat preservation, taken out of the furnace, heated and rolled, and cooled for 29 h;
(8) and (3) blank opening rolling procedure: and closing a roller cooling water system in the blank starting heating and rolling process, adopting a temperature-increasing rolling mode, controlling the initial rolling temperature of 1055 ℃, the final rolling temperature of 980 ℃, and slowly cooling the rolled stack at the stacking temperature of 520 ℃ for 72 h.
The finished steel plate of the embodiment is comprehensively inspected, no crack is formed on the surface of the steel plate, metallographic microstructure observation is immediately carried out, no micro crack is formed on the surface of the steel plate, the cracks on the surface of the steel plate are effectively controlled through the control measures of the production process of the embodiment, the one-time inspection qualified rate of the steel plate is 97%, and the mechanical property qualified rate of the steel plate is 100%.
Example 6
The specification of the chromium molybdenum alloy steel plate SA387MGr9Cl1 with high chromium content of the embodiment is 23mm 2980mm 9750mm, C: 0.10%, Mo: 1.10%, Cr: 9.3%, the production process of reducing the surface cracks of the chromium-molybdenum alloy steel plate with high chromium content comprises the working procedures of smelting, pouring, steel ingot annealing, steel ingot cogging and cutting, cogging material primary annealing, cogging material cleaning, cogging material secondary annealing and cogging material rolling, and the specific process steps are as follows:
(1) smelting: carrying out low-temperature dephosphorization in the oxygen melting period of electric furnace steelmaking at the ladle temperature of 1605 ℃ and carrying out slag-free tapping; the white slag retention time in the refining process is 39min, the vacuum degree in the vacuum treatment process is 48Pa, the vacuum retention time is 33min, and harmful elements are controlled at the smelting end point: p: 0.002%, S: 0.005%, Sb: 0.001%, Sn: 0.001%, As: 0.010%;
(2) a casting process: the temperature of the casting ladle is 1563 ℃, the casting temperature is 1542 ℃, 3 kg of Al-RE alloy rare earth modifier per ton of steel is added into the molten steel before casting, the RE content of the Al-RE alloy rare earth modifier is 1.8%, and the balance is Al; the unit weight of the obtained steel ingot is 21 t;
(3) annealing the steel ingot: putting the steel ingot into a soaking pit furnace for annealing, heating the steel ingot into the furnace to 910 ℃ after 23.5 hours, keeping the temperature for 50 hours, cooling the steel ingot for 24 hours, and discharging the steel ingot from the furnace to 255 ℃ for cogging and rolling;
(4) steel ingot cogging and cutting procedures: heating the steel ingot by using a soaking pit furnace, loading the steel ingot at the furnace temperature of 660 ℃, heating the steel ingot for 3 hours after loading, wherein the heating speed is 60 ℃/h, heating the steel ingot to 902 ℃, preserving heat for 7.5 hours, heating the steel ingot to 1240 ℃ according to the heating speed of 65 ℃/h, preserving heat for 17 hours, discharging the steel ingot out of the furnace, rolling and cogging, starting high-pressure water to remove scale in the rolling process, controlling the water pressure to be 21.5MPa, forming an angle between a water nozzle and the steel ingot by 78 degrees, wherein the thickness of the steel ingot is 140mm, the specification of the steel ingot is 140mm × 2550mm 2700mm, cutting off a cap opening of the steel ingot after cogging, and controlling the surface temperature of the steel ingot to be 290 ℃ when the steel ingot is cut;
(5) a blank opening primary annealing process: the surface temperature of the blank is 280 ℃ before the blank is placed into a furnace for annealing, the furnace temperature is 170 ℃, the temperature of the blank is raised to 700 ℃ after the blank is placed into the furnace, the heat preservation is started, the temperature raising time is 26 hours, the heat preservation time is 48 hours, the temperature is reduced to 250 ℃ after the heat preservation is finished, the blank is taken out of the furnace, the surface of the blank is scalped and cleaned, and the temperature reduction time is 31 hours;
(6) blank cleaning procedure: removing surface crack defects by adopting a carbon arc gouging mode, wherein the diameter of a used carbon rod is 7 mm; the polarity working mode of the power supply is direct current reverse connection, the blank is connected with the negative electrode, and the carbon rod is connected with the positive electrode; the current is selected to be in direct proportion to the diameter of the carbon rod, the current is 315A, and the voltage is 41V; the planing speed is 1.10m/min, the compressed air pressure is 0.59MPa, the extending length of the carbon rod is 97mm, when the burning loss of the carbon rod is reduced to 26mm continuously, the extending length of the carbon rod is adjusted to 97mm again, the included angle between the carbon rod and the blank surface is 53 degrees, and the arc length is 1.1 mm;
(7) and (3) blank opening secondary annealing process: after the air gouging is cleaned, the blank is put into a furnace, heated to 300 ℃ at a heating rate of 60 ℃/h, kept warm for 3.5h, then continuously heated to 700 ℃, kept warm for 50h, cooled to 230 ℃ after heat preservation, taken out of the furnace and rolled, and cooled for 28 h;
(8) and (3) blank opening rolling procedure: and closing a roller cooling water system in the blank starting heating and rolling process, adopting a temperature-increasing rolling mode, controlling the initial rolling temperature to be 1065 ℃, controlling the final rolling temperature to be 1000 ℃, and slowly cooling the rolled stack at the stacking temperature of 580 ℃ for 58 h.
The finished steel plate of the embodiment is comprehensively inspected, no crack is formed on the surface of the steel plate, metallographic microstructure observation is immediately carried out, no micro crack is formed on the surface of the steel plate, the cracks on the surface of the steel plate are effectively controlled through the control measures of the production process of the embodiment, the one-time inspection qualification rate of the steel plate is 96%, and the mechanical property qualification rate of the steel plate is 98%.
Example 7
The specification of the chromium molybdenum alloy steel plate SA387MGr9Cl1 with high chromium content of the embodiment is 23mm 2950mm 9800mm, C: 0.10%, Mo: 0.90%, Cr: 8.5%, the production process of reducing the surface cracks of the chromium-molybdenum alloy steel plate with high chromium content comprises the working procedures of smelting, pouring, steel ingot annealing, steel ingot cogging and cutting, cogging material primary annealing, cogging material cleaning, cogging material secondary annealing and cogging material rolling, and the specific process steps are as follows:
(1) smelting: removing P at low temperature in the oxygen melting period of electric furnace steelmaking, wherein the ladle temperature is 1650 ℃, and tapping without slag; the white slag retention time in the refining process is 36min, the vacuum degree in the vacuum treatment process is 53Pa, the vacuum retention time is 40min, and harmful elements are controlled at the smelting end point: p: 0.001%, S: 0.002%, Sb: 0.003%, Sn: 0.004%, As: 0.006%;
(2) a casting process: the casting ladle temperature is 1556 ℃, the casting temperature is 1528 ℃, 3 kg/t of Al-RE alloy rare earth modifier is added into the molten steel before casting, the RE content of the Al-RE alloy rare earth modifier is 1.5%, and the balance is Al; the unit weight of the obtained steel ingot is 22 t;
(3) annealing the steel ingot: putting the steel ingot into a soaking pit furnace for annealing, heating the steel ingot into the furnace for 24 hours to 900 ℃, keeping the temperature for 50 hours, cooling the steel ingot for 23.5 hours, and discharging the steel ingot from the furnace for cogging rolling after cooling the steel ingot to 285 ℃;
(4) steel ingot cogging and cutting procedures: heating the steel ingot by using a soaking pit furnace, loading the steel ingot at the furnace temperature of 685 ℃, heating after 3.5h of loading, heating at the heating speed of 63 ℃/h, keeping the temperature for 7.5h when the temperature rises to 904 ℃, heating to 1250 ℃ according to the heating speed of 63 ℃/h, keeping the temperature for 19.5h, then discharging from the furnace, rolling and cogging, starting high-pressure water for descaling in the rolling process, controlling the water pressure to be 22MPa, controlling the included angle of a water nozzle and the steel ingot to be 75 degrees, controlling the thickness of the steel ingot to be 150mm, controlling the specification of the steel ingot to be 140mm, 2580mm and 2750mm, cutting off a cap opening of the steel ingot after cogging, and controlling the surface temperature of the steel ingot to be 320 ℃ when the steel ingot is cut;
(5) a blank opening primary annealing process: the surface temperature of the blank is 260 ℃ before the blank is placed into a furnace for annealing, the furnace temperature is 140 ℃, the temperature of the blank is raised to 665 ℃ after the blank is placed into the furnace, the heat preservation is started, the temperature raising time is 29 hours, the heat preservation time is 60 hours, the temperature is reduced to 200 ℃ after the heat preservation is finished, the blank is taken out of the furnace, the surface of the blank is scalped and cleaned, and the temperature reduction time is 25 hours;
(6) blank cleaning procedure: removing surface crack defects by adopting a carbon arc gouging mode, wherein the diameter of a used carbon rod is 6 mm; the polarity working mode of the power supply is direct current reverse connection, the blank is connected with the negative electrode, and the carbon rod is connected with the positive electrode; the current is selected to be in direct proportion to the diameter of the carbon rod, the current is 325A, and the voltage is 40.2V; the planing speed is 0.70m/min, the pressure of compressed air is 0.57MPa, the extending length of the carbon rod is 86mm, when the burning loss of the carbon rod is reduced to 28mm continuously, the extending length of the carbon rod is adjusted to 86mm again, the included angle between the carbon rod and the surface of the blank is 46 degrees, and the arc length is 1.6 mm;
(7) and (3) blank opening secondary annealing process: after the air gouging is cleaned, the blank is put into a furnace, heated to 350 ℃ at the heating rate of 55 ℃/h, kept warm for 4h, then continuously heated to 700 ℃ at the heating rate of 55 ℃/h, kept warm for 48h, cooled to 250 ℃ after the heat preservation, taken out of the furnace and rolled, and cooled for 25 h;
(8) and (3) blank opening rolling procedure: and closing a roller cooling water system in the blank starting heating and rolling process, adopting a temperature-increasing rolling mode, controlling the initial rolling temperature to be 1075 ℃, controlling the final rolling temperature to be 985 ℃, slowly cooling the rolled stack at the stacking temperature of 560 ℃, and keeping the stacking time to be 65 h.
The finished steel plate of the embodiment is comprehensively inspected, no crack is formed on the surface of the steel plate, metallographic microstructure observation is immediately carried out, no micro crack is formed on the surface of the steel plate, the cracks on the surface of the steel plate are effectively controlled through the control measures of the production process of the embodiment, the one-time inspection qualification rate of the steel plate is 98%, and the mechanical property qualification rate of the steel plate is 99%.
Example 8
The specification of the chromium molybdenum alloy steel plate SA387MGr9Cl1 with high chromium content of the embodiment is 14mm 3200mm 17500mm, C: 0.13%, Mo: 0.96%, Cr: 9.6%, the production process of reducing the surface cracks of the chromium-molybdenum alloy steel plate with high chromium content comprises the working procedures of smelting, pouring, steel ingot annealing, steel ingot cogging and cutting, cogging material primary annealing, cogging material cleaning, cogging material secondary annealing and cogging material rolling, and the specific process steps are as follows:
(1) smelting: removing P at low temperature in the oxygen melting period of electric furnace steelmaking, wherein the ladle temperature is 1630 ℃, and tapping without slag; the white slag retention time in the refining process is 30min, the vacuum degree in the vacuum treatment process is 55Pa, the vacuum retention time is 34min, and harmful elements are controlled at the smelting end point: p: 0.003%, S: 0.004%, Sb: 0.002%, Sn: 0.003%, As: 0.012%;
(2) a casting process: the temperature of the casting ladle is 1545 ℃, the casting temperature is 1545 ℃, 3.4 kg of Al-RE alloy rare earth modifier per t of steel is added into the molten steel before casting, the RE content of the Al-RE alloy rare earth modifier is 1.8%, and the balance is Al; the obtained steel ingot is single-weight, 21 t;
(3) annealing the steel ingot: putting the steel ingot into a soaking pit furnace for annealing, heating the steel ingot to 950 ℃ after 23.5 hours of putting the steel ingot into the furnace, keeping the temperature for 48 hours, cooling the steel ingot for 22 hours, and discharging the steel ingot from the furnace after cooling the steel ingot to 300 ℃ for cogging rolling;
(4) steel ingot cogging and cutting procedures: heating the steel ingot by using a soaking pit furnace, loading the steel ingot at the furnace temperature of 700 ℃, heating for 4 hours after loading, heating at the heating speed of 70 ℃/h, heating to 900 ℃, keeping the temperature for 8 hours, heating to 1240 ℃ according to the heating speed of 70 ℃/h, keeping the temperature for 17.5 hours, discharging from the furnace, rolling and cogging, starting high-pressure water to remove scale in the rolling process, controlling the water pressure to be 19MPa, enabling a water nozzle to form an angle of 75 degrees with the steel billet, enabling the thickness of the billet to be 140mm, enabling the specification of the billet to be 200mm 1950mm 2450mm, cutting off a cap opening of the billet after cogging, and enabling the surface temperature of the billet during cutting to be 250 ℃;
(5) a blank opening primary annealing process: the surface temperature of the blank is 250 ℃ before the blank is placed into a furnace for annealing, the furnace temperature is 200 ℃, the temperature of the blank is raised to 660 ℃ after the blank is placed into the furnace, the heat preservation is started, the temperature raising time is 32 hours, the heat preservation time is 55 hours, the temperature is reduced to 230 ℃ after the heat preservation, the blank is taken out of the furnace, the surface of the blank is scalped and cleaned, and the temperature reduction time is 24 hours;
(6) blank cleaning procedure: removing surface crack defects by adopting a carbon arc gouging mode, wherein the diameter of a used carbon rod is 8 mm; the polarity working mode of the power supply is direct current reverse connection, the blank is connected with the negative electrode, and the carbon rod is connected with the positive electrode; the current is selected to be in direct proportion to the diameter of the carbon rod, the current is 285A, and the voltage is 42V; the planing speed is 1.50m/min, the compressed air pressure is 0.60MPa, the extending length of the carbon rod is 85mm, when the burning loss of the carbon rod is reduced to 30mm continuously, the extending length of the carbon rod is adjusted to 85mm again, the included angle between the carbon rod and the blank surface is 60 degrees, and the arc length is 1.0 mm;
(7) and (3) blank opening secondary annealing process: after the air gouging is cleaned, the blank is put into a furnace, heated to 347 ℃ at the heating rate of 50 ℃/h, kept warm for 4h, then continuously heated to 650 ℃, kept warm for 53h, cooled to 245 ℃ after the heat preservation, taken out of the furnace and rolled, and cooled for 30 h;
(8) and (3) blank opening rolling procedure: and closing a roller cooling water system in the blank starting heating rolling process, adopting a temperature-raising rolling mode, controlling the initial rolling temperature to be 1050 ℃, controlling the final rolling temperature to be 950 ℃, slowly cooling the rolled stack at the stacking temperature of 540 ℃, and keeping the stacking time to be 64 h.
The finished steel plate of the embodiment is comprehensively inspected, no crack is formed on the surface of the steel plate, metallographic microstructure observation is immediately carried out, no micro crack is formed on the surface of the steel plate, the cracks on the surface of the steel plate are effectively controlled through the control measures of the production process of the embodiment, the one-time inspection qualification rate of the steel plate is 98%, and the mechanical property qualification rate of the steel plate is 97%.
Example 9
The specification of the chromium molybdenum alloy steel plate SA387MGr9Cl1 with high chromium content of the embodiment is 14.27 × 3210 × 17500, C: 0.13%, Mo: 0.95%, Cr: 8.9%, the production process of reducing the surface cracks of the chromium-molybdenum alloy steel plate with high chromium content comprises the working procedures of smelting, pouring, steel ingot annealing, steel ingot cogging and cutting, cogging material primary annealing, cogging material cleaning, cogging material secondary annealing and cogging material rolling, and the specific process steps are as follows:
(1) smelting: removing P at low temperature in the oxygen melting period of electric furnace steelmaking, wherein the ladle temperature is 1610 ℃, and tapping is carried out without slag; the white slag retention time in the refining process is 45min, the vacuum degree in the vacuum treatment process is 54Pa, the vacuum retention time is 31min, and harmful elements are controlled at the smelting end point: p: 0.006%, S: 0.001%, Sb: 0.003%, Sn: 0.002%, As: 0.009%;
(2) a casting process: the temperature of the casting ladle is 1550 ℃, the casting temperature is 1522 ℃, 3.9 kg of Al-RE alloy rare earth modifier per t of steel is added into the molten steel before casting, the RE content of the Al-RE alloy rare earth modifier is 2.0%, and the balance is Al; the unit weight of the obtained steel ingot is 21 t;
(3) annealing the steel ingot: putting the steel ingot into a soaking pit furnace for annealing, heating the steel ingot into the furnace to 930 ℃ after 20.5 hours, keeping the temperature for 59 hours, cooling the steel ingot for 22.5 hours, and discharging the steel ingot from the furnace to 260 ℃ for cogging and rolling;
(4) steel ingot cogging and cutting procedures: heating the steel ingot by using a soaking pit furnace, charging the steel ingot at the furnace temperature of 610 ℃, heating after charging for 2.5h at the heating speed of 75 ℃/h, heating to 915 ℃ and preserving heat for 6h, then heating to 1248 ℃ according to the heating speed of 75 ℃/h, preserving heat for 15h, discharging from the furnace, rolling and cogging, starting high-pressure water for descaling in the rolling process, controlling the water pressure to be 20MPa, controlling the water nozzle to form an angle of 71 degrees with the steel billet, enabling the thickness of the billet to be 160mm, enabling the specification of the billet to be 200mm 1960, cutting off a cap opening of the billet after cogging, and enabling the surface temperature of the billet during cutting to be 300 ℃;
(5) a blank opening primary annealing process: the surface temperature of the blank is 210 ℃ before the blank is put into a furnace for annealing, the furnace temperature is 130 ℃, the temperature of the blank is raised to 695 ℃ after the blank is put into the furnace, the heat preservation is started, the temperature raising time is 24.5 hours, the heat preservation time is 56 hours, the temperature is reduced to 220 ℃ after the heat preservation is finished, the blank is taken out of the furnace, the surface of the blank is scalped and cleaned, and the temperature reduction time is 35 hours;
(6) blank cleaning procedure: removing surface crack defects by adopting a carbon arc gouging mode, wherein the diameter of a used carbon rod is 6.2 mm; the polarity working mode of the power supply is direct current reverse connection, the blank is connected with the negative electrode, and the carbon rod is connected with the positive electrode; the current is selected in proportion to the diameter of the carbon rod, the current is 345A, and the voltage is 41.5V; the planing speed is 0.70m/min, the compressed air pressure is 0.56MPa, the extending length of the carbon rod is 100mm, when the burning loss of the carbon rod is reduced to 29.5mm continuously, the extending length of the carbon rod is adjusted to 100mm again, the included angle between the carbon rod and the surface of the blank is 51 degrees, and the arc length is 1.5 mm;
(7) and (3) blank opening secondary annealing process: after the air gouging is cleaned, the blank is put into a furnace, heated to 310 ℃ at the heating rate of 40 ℃/h, kept warm for 3.5h, then continuously heated to 670 ℃, kept warm for 57h, cooled to 205 ℃ after the heat preservation, taken out of the furnace and rolled, and cooled for 26 h;
(8) and (3) blank opening rolling procedure: and closing a roller cooling water system in the blank starting heating rolling process, adopting a temperature-controlled rolling mode, controlling the initial rolling temperature to be 1100 ℃, controlling the final rolling temperature to be 990 ℃, slowly cooling the rolled stack, and keeping the stacking temperature to be 515 ℃ for 50 hours.
The finished steel plate of the embodiment is comprehensively inspected, no crack is formed on the surface of the steel plate, metallographic microstructure observation is immediately carried out, no micro crack is formed on the surface of the steel plate, the cracks on the surface of the steel plate are effectively controlled through the control measures of the production process of the embodiment, the one-time inspection qualified rate of the steel plate is 97%, and the mechanical property qualified rate of the steel plate is 100%.
Example 10
The specification of the chromium molybdenum alloy steel plate SA387MGr9Cl1 with high chromium content of the embodiment is 21 × 2550 × 25300, C: 0.12%, Mo: 0.94%, Cr: 10.0%, the production process of reducing the surface cracks of the chromium-molybdenum alloy steel plate with high chromium content comprises the working procedures of smelting, pouring, steel ingot annealing, steel ingot cogging and cutting, cogging stock primary annealing, cogging stock cleaning, cogging stock secondary annealing and cogging stock rolling, and the specific process steps are as follows:
(1) smelting: removing P at low temperature in the oxygen melting period of electric furnace steelmaking, wherein the ladle temperature is 1640 ℃, and tapping without slag; the white slag retention time in the refining process is 32min, the vacuum degree in the vacuum treatment process is 45Pa, the vacuum retention time is 30min, and harmful elements are controlled at the smelting end point: p: 0.005%, S: 0.005%, Sb: 0.002%, Sn: 0.005%, As: 0.005 percent;
(2) a casting process: the temperature of the casting ladle is 1562 ℃, the casting temperature is 1530 ℃, 3.5 kg of Al-RE alloy rare earth modifier per t of steel is added into the molten steel before casting, the RE content of the Al-RE alloy rare earth modifier is 1.7%, and the balance is Al; the unit weight of the obtained steel ingot is 21 t;
(3) annealing the steel ingot: putting the steel ingot into a soaking pit furnace for annealing, heating the steel ingot into the furnace to 945 ℃ after 22.5 hours, preserving the heat for 58 hours, cooling for 23.5 hours, cooling to 280 ℃, discharging and cogging;
(4) steel ingot cogging and cutting procedures: heating the steel ingot by using a soaking pit furnace, loading the steel ingot at the furnace temperature of 650 ℃, heating the steel ingot for 2 hours after loading, wherein the heating speed is 72 ℃/h, heating the steel ingot to 916 ℃, preserving heat for 6.5 hours, heating the steel ingot to 1233 ℃ according to the heating speed of 72 ℃/h, preserving heat for 15.5 hours, discharging the steel ingot out of the furnace, rolling and cogging the steel ingot, starting high-pressure water to remove scale in the rolling process, controlling the water pressure to be 18MPa, ensuring the included angle between a water nozzle and the steel ingot to be 77 degrees, ensuring the thickness of the steel ingot to be 180mm, ensuring the specification of the steel ingot to be 200mm × 3220, cutting off a cap opening of the steel ingot after cogging, and ensuring the surface temperature of the steel ingot to be 255 ℃ when cutting;
(5) a blank opening primary annealing process: the surface temperature of the blank is 200 ℃ before the blank is placed into a furnace for annealing, the furnace temperature is 160 ℃, the temperature of the blank is raised to 670 ℃ after the blank is placed into the furnace, the heat preservation is started, the temperature raising time is 27 hours, the heat preservation time is 49 hours, the temperature is reduced to 245 ℃ after the heat preservation is finished, the blank is taken out of the furnace, the surface of the blank is scalped and cleaned, and the temperature reduction time is 33 hours;
(6) blank cleaning procedure: removing surface crack defects by adopting a carbon arc gouging mode, wherein the diameter of a used carbon rod is 7.5 mm; the polarity working mode of the power supply is direct current reverse connection, the blank is connected with the negative electrode, and the carbon rod is connected with the positive electrode; the current is selected in direct proportion to the diameter of the carbon rod, the current is 300A, and the voltage is 40.8V; the planing speed is 0.60m/min, the pressure of compressed air is 0.52MPa, the extending length of the carbon rod is 96mm, when the burning loss of the carbon rod is reduced to 26mm continuously, the extending length of the carbon rod is adjusted to 96mm again, the included angle between the carbon rod and the blank surface is 59 degrees, and the arc length is 1.8 mm;
(7) and (3) blank opening secondary annealing process: after the air gouging is cleaned, the blank is put into a furnace, heated to 320 ℃ at a heating rate of 60 ℃/h, kept warm for 3.2h, then continuously heated to 655 ℃, kept warm for 59h, cooled to 220 ℃ after heat preservation, taken out of the furnace and rolled, and cooled for 31 h;
(8) and (3) blank opening rolling procedure: and closing a roller cooling water system in the blank starting heating rolling process, adopting a temperature-increasing rolling mode, controlling the initial rolling temperature to be 1070 ℃, controlling the final rolling temperature to be 955 ℃, slowly cooling the rolled stack at 570 ℃, and keeping the stacking time to be 48 h.
The finished steel plate of the embodiment is comprehensively inspected, no crack is formed on the surface of the steel plate, metallographic microstructure observation is immediately carried out, no micro crack is formed on the surface of the steel plate, the cracks on the surface of the steel plate are effectively controlled through the control measures of the production process of the embodiment, the one-time inspection qualification rate of the steel plate is 95%, and the mechanical property qualification rate of the steel plate is 98%.
Example 11
The specification of the chromium molybdenum alloy steel plate SA387MGr9Cl with high chromium content of the embodiment is 21 × 2540 × 25300, C: 0.12%, Mo: 0.96%, Cr: 9.8%, the production process of reducing the surface cracks of the chromium-molybdenum alloy steel plate with high chromium content comprises the working procedures of smelting, pouring, steel ingot annealing, steel ingot cogging and cutting, cogging material primary annealing, cogging material cleaning, cogging material secondary annealing and cogging material rolling, and the specific process steps are as follows:
(1) smelting: removing P at low temperature in the oxygen melting period of electric furnace steelmaking, wherein the ladle temperature is 1620 ℃, and tapping is carried out without slag; the white slag retention time in the refining process is 33min, the vacuum degree in the vacuum treatment process is 51Pa, the vacuum retention time is 32min, and harmful elements are controlled at the smelting end point: p: 0.006%, S: 0.004%, Sb: 0.001%, Sn: 0.001%, As: 0.011 percent;
(2) a casting process: the temperature of the casting ladle is 1547 ℃, the casting temperature is 1540 ℃, 3.7 kg of Al-RE alloy rare earth modifier per t of steel is added into the molten steel before casting, the RE content of the Al-RE alloy rare earth modifier is 1.9%, and the balance is Al; the unit weight of the obtained steel ingot is 21 t;
(3) annealing the steel ingot: putting the steel ingot into a soaking pit furnace for annealing, heating the steel ingot into the furnace to 942 ℃ after 21h, keeping the temperature for 57h, cooling the steel ingot for 22h, cooling the steel ingot to 290 ℃, discharging the steel ingot out of the furnace and cogging and rolling the steel ingot;
(4) steel ingot cogging and cutting procedures: heating the steel ingot by using a soaking pit furnace, loading the steel ingot at the furnace temperature of 630 ℃, heating after loading for 2.5h at the heating speed of 74 ℃/h, heating to 918 ℃, preserving heat for 6h, heating to 1239 ℃ according to the heating speed of 74 ℃/h, preserving heat for 16h, discharging from the furnace, rolling and cogging, starting high-pressure water to remove scale in the rolling process, controlling the water pressure to be 21MPa, controlling the included angle between a water nozzle and the steel billet to be 70 degrees, enabling the thickness of the blank to be 170mm, enabling the specification of the blank to be 200mm x 2400 x 3250, cutting off a cap opening of the blank after cogging, and enabling the surface temperature of the blank to be 310 ℃ when cutting;
(5) a blank opening primary annealing process: the surface temperature of the blank is 240 ℃ before the blank is placed into a furnace for annealing, the furnace temperature is 185 ℃, the temperature of the blank is raised to 685 ℃ after the blank is placed into the furnace, the heat preservation is started, the temperature rising time is 25 hours, the heat preservation time is 50 hours, the temperature is reduced to 205 ℃ after the heat preservation is finished, the blank is taken out of the furnace, the surface of the blank is scalped and cleaned, and the temperature reduction time is 25 hours;
(6) blank cleaning procedure: removing surface crack defects by adopting a carbon arc gouging mode, wherein the diameter of a used carbon rod is 6.5 mm; the polarity working mode of the power supply is direct current reverse connection, the blank is connected with the negative electrode, and the carbon rod is connected with the positive electrode; the current is selected in direct proportion to the diameter of the carbon rod, the current is 340A, and the voltage is 40.5V; the planing speed is 0.95m/min, the compressed air pressure is 0.54MPa, the extending length of the carbon rod is 98mm, when the burning loss of the carbon rod is reduced to 26.5mm continuously, the extending length of the carbon rod is adjusted to 98mm again, the included angle between the carbon rod and the blank surface is 45 degrees, and the arc length is 1.2 mm;
(7) and (3) blank opening secondary annealing process: after the air gouging is cleaned, the blank is put into a furnace, heated to 305 ℃ at a heating rate of 60 ℃/h, kept warm for 3.8h, then continuously heated to 660 ℃, kept warm for 49h, cooled to 210 ℃ after heat preservation, taken out of the furnace and rolled, and cooled for 27 h;
(8) and (3) blank opening rolling procedure: and (3) closing a roller cooling water system in the blank starting heating rolling process, adopting a temperature-raising rolling mode, controlling the initial rolling temperature to be 1095 ℃, controlling the final rolling temperature to be 980 ℃, and slowly cooling the rolled stack at the stacking temperature of 515 ℃ for 52 h.
The finished steel plate of the embodiment is comprehensively inspected, no crack is formed on the surface of the steel plate, metallographic microstructure observation is immediately carried out, no micro crack is formed on the surface of the steel plate, the cracks on the surface of the steel plate are effectively controlled through the control measures of the production process of the embodiment, the one-time inspection qualification rate of the steel plate is 98%, and the mechanical property qualification rate of the steel plate is 97%.
Although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made thereto without departing from the spirit and scope of the invention and it is intended to cover in the claims the invention as defined in the appended claims.

Claims (7)

1. A production process for reducing surface cracks of a chromium-molybdenum alloy steel plate with high chromium content is characterized by comprising the working procedures of smelting, casting, annealing of steel ingots, cogging and cutting of the steel ingots, primary annealing of cogging materials, cleaning of the cogging materials, secondary annealing of the cogging materials and rolling of the cogging materials; in the casting process, the casting ladle temperature is 1545-1565 ℃, the casting temperature is controlled at 1520-1545 ℃, and 3-4 kg of Al-RE alloy rare earth modifier per ton of steel is added into the molten steel before casting; in the cogging stock rolling procedure, a roller cooling water system is closed in the cogging stock heating and rolling process, a temperature-increasing rolling mode is adopted, the cogging temperature is 1050-1100 ℃, the finishing temperature is controlled to be not less than 950 ℃, the stacking is slowly cooled after rolling, the stacking temperature is more than 500 ℃, and the stacking time is 48-72 hours;
in the blank opening secondary annealing process, after the blank is cleaned by the air gouging, the blank is put into a furnace and heated to 300-350 ℃ at a heating rate of 40-60 ℃/h, heat is preserved for 3-4 h, then the blank is continuously heated to 650-700 ℃, the heat is preserved for 48-60 h, the blank is taken out of the furnace after the heat preservation is finished and the temperature is reduced to 200-250 ℃, and the temperature reduction time is more than 24 h;
the production process is suitable for producing the high-strength chromium-molybdenum alloy steel plate for the power equipment and the petrochemical industry pipe fittings, which has the thickness of 12-30 mm, the carbon content of 0.1-0.13%, the molybdenum content of 0.9-1.1% and the chromium content of 8-10%;
the one-time inspection qualification rate of the steel plate in the production process is more than or equal to 96%, and the mechanical property qualification rate of the steel plate is more than or equal to 98%.
2. The process for producing the chromium-molybdenum alloy steel plate with reduced surface cracks with high chromium content as claimed in claim 1, wherein the smelting process comprises the steps of carrying out low-temperature dephosphorization in the oxygen melting period of electric furnace steelmaking, wherein the ladle temperature is more than 1600 ℃, and carrying out slag-free tapping; the white slag retention time in the refining process is more than or equal to 30min, the vacuum degree in the vacuum treatment process is less than or equal to 55Pa, the vacuum retention time is more than or equal to 30min, and harmful elements are controlled at the smelting end point: p is less than or equal to 0.006 percent, S is less than or equal to 0.006 percent, Sb is less than or equal to 0.003 percent, Sn is less than or equal to 0.005 percent, and As is less than or equal to 0.012 percent.
3. The production process for reducing the surface cracks of the chromium-molybdenum alloy steel plate with the high chromium content as claimed in claim 1, characterized in that in the steel ingot annealing step, the steel ingot is put into a soaking furnace for annealing, the temperature of the steel ingot is raised to 900-950 ℃ after 20-24 hours of putting into the furnace, the heat preservation time is 48-60 hours, the temperature reduction time is controlled to 22-24 hours, and the steel ingot is taken out of the furnace to 250-300 ℃ for heating cogging and rolling.
4. The production process for reducing the surface cracks of the chromium-molybdenum alloy steel plate with the high chromium content, according to the claim 1, is characterized in that the steel ingot is cogging and cut, the steel ingot is heated by a soaking furnace, the steel ingot is loaded at the furnace temperature of less than or equal to 700 ℃, the temperature is raised after being loaded for 2-4 h, the temperature raising speed is less than or equal to 75 ℃/h, the temperature is raised to 900-920 ℃, the temperature is kept for 6-8 h, then the temperature is raised to 1230-1250 ℃ according to the temperature raising speed of less than or equal to 75 ℃/h, the temperature is kept for 15-20 h, and then the steel ingot is taken out of the furnace and is cogging; starting high-pressure water for descaling in the rolling process, controlling the water pressure to be 18-22 MPa, and enabling the included angle between a water nozzle and a steel billet to be 70-80 degrees; the thickness of the blank is controlled to be 140-200 mm, the cap opening of the blank is cut off after the blank is opened, the surface temperature of the blank is controlled to be more than or equal to 250 ℃ during cutting, and cracks are prevented from being generated after cutting.
5. The production process for reducing the surface cracks of the chromium-molybdenum alloy steel plate with the high chromium content as claimed in claim 1, characterized in that in the primary blank annealing process, the surface temperature of the blank is controlled to be not less than 200 ℃ before the blank is placed into a furnace for annealing, the furnace temperature is not more than 200 ℃, the temperature of the blank is raised to 650-700 ℃ after the blank is placed into the furnace, the temperature is kept, the temperature raising time is more than 24h, the temperature keeping time is 48-60 h, the temperature is reduced to 200-250 ℃ after the temperature keeping is finished, the blank is taken out of the furnace, the surface of the blank is scalped and cleaned, and the temperature reduction time is kept at 24-36 h.
6. The production process for reducing the surface cracks of the chromium-molybdenum alloy steel plate with high chromium content as claimed in claim 1, wherein in the blank cleaning process, the surface crack defects are cleaned in a carbon arc gouging mode, and the diameter of a used carbon rod is 6-8 mm; the polarity working mode of the power supply is direct current reverse connection, the blank is connected with the negative electrode, and the carbon rod is connected with the positive electrode; the current is selected in proportion to the diameter of the carbon rod, the current is controlled to be 285-345A, and the voltage is 40-42V; the planing speed is controlled to be 0.6-1.5 m/min, the compressed air pressure is controlled to be 0.5-0.6 MPa, the extending length of the carbon rod is controlled to be 85-100 mm, when the burning loss of the carbon rod is reduced to 25-30 mm continuously, the extending length of the carbon rod is adjusted to be 85-100 mm again, the included angle between the carbon rod and the surface of a blank is 45-60 degrees, and the arc length is controlled to be 1-2 mm.
7. The production process for reducing the surface cracks of the chromium-molybdenum alloy steel plate with high chromium content as claimed in claim 1, wherein the RE content of the Al-RE alloy rare earth modifier is 1.5-2%, and the balance is Al.
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