Large steel casting forging process

Abstract

The invention provides a large steel casting forging process. The large steel casting forging process comprises the following steps that S1, raw materials are prepared; s2, smelting; s3, pouring is conducted; s4, heating in a heating furnace; s5, forging; s6, heat treatment; and S7, quality detection. According to the forging technology for the large steel casting, through the measures of optimizing the heating technology, introducing novel forging equipment, improving the forging technology, strengthening quality detection and the like, the quality stability of the steel casting is effectively improved, energy consumption is reduced, and the production efficiency and the size precision control capacity are improved; high-quality raw materials and an advanced smelting technology are adopted, it is ensured that chemical components of the steel casting are uniform, the performance and reliability of the steel casting are improved, reasonable preheating treatment and forging processes are adopted, the thermal stress and deformation of the steel casting are reduced, the uniformity and compactness of the internal structure of the steel casting are improved, and a quality detection system is improved; and it is guaranteed that the quality of the steel casting meets the design requirement, and the market competitiveness of products is improved.

Description

Technical Field

[0001] The invention relates to the technical field of steel casting forging, in particular to a large steel casting forging process. Background Art

[0002] Large steel castings are widely used in many industrial fields, such as heavy machinery manufacturing, large shipbuilding, etc. The traditional forging process of large steel castings usually includes material preparation, smelting, pouring, forging and other steps.

[0003] Due to the large size and heavy weight of large steel castings, local overheating or overcooling is prone to occur during the forging process, resulting in uneven internal structure of the casting, affecting the stability of product quality. The forging process of large steel castings is usually more complicated, requiring multiple heating and forging operations, and the interval between each operation is long, resulting in low production efficiency. Due to the large size of large steel castings, deformation is prone to occur during the forging process, making it difficult to control dimensional accuracy, increasing the difficulty of subsequent processing, and may also cause the product to fail to meet design requirements.

[0004] Therefore, it is necessary to provide a large steel casting forging process to solve the above-mentioned technical problems. Summary of the invention

[0005] The invention provides a large steel casting forging process, which solves the problems of unstable quality, high energy consumption, low production efficiency and difficult to control dimensional accuracy in the traditional large steel casting forging process.

[0006] To solve the above technical problems, the present invention provides a large steel casting forging process, comprising the following steps: S1: raw material preparation; S2: smelting; S3: pouring; S4: heating in a heating furnace; S5: forging; S6: heat treatment; S7: quality inspection.

[0007] Preferably, the raw material preparation step includes the following steps: S11: preparing high-quality G20Mn5N steel ingots; S12: performing ultrasonic flaw detection on the steel ingots to check internal defects using an ultrasonic flaw detector, checking the surface and near-surface crack defects of the G20Mn5N steel ingots using a magnetic particle flaw detector, and selecting G20Mn5N steel ingots with smooth surfaces.

[0008] Preferably, the smelting step includes the following steps: S21: placing the G20Mn5N steel ingot into a smelting furnace for smelting, using an electric arc furnace for smelting, and adding alloy elements chromium, nickel and molybdenum to improve the strength, toughness and corrosion resistance of the steel; S22: During the electric arc furnace smelting, electromagnetic stirring is used to evenly distribute the added alloy elements in the molten steel.

[0009] Preferably, the pouring step includes the following steps: S31: the smelted molten steel is allowed to stand in a steel ladle, and the slag and other impurities mixed into the steel during tapping are allowed to float up and then removed; S32: an ingot mold is selected, the integrity and cleanliness of the mold are checked, and a release agent is applied to the inner wall of the mold to facilitate smooth demolding of the ingot after forming; S33: the spout of the steel ladle is aligned with the pouring gate of the ingot mold, and the spout is slowly opened to allow the molten steel to flow smoothly into the ingot mold. During the pouring process, the continuous injection of the molten steel is maintained to avoid interruptions or pauses, prevent stratification defects inside the ingot, and control the pouring speed.

[0010] Preferably, the heating furnace heating step includes the following steps: S41: using a large gas heating furnace to heat the formed G20Mn5N steel ingot for forging; S42: the initial forging temperature of the G20Mn5N steel is set at 1200-1250°C. During the heating process, it is slowly heated to about 600°C at a rate of 50-100°C / h for insulation, and then continued to be heated to the initial forging temperature at a rate of 100-150°C / h. The insulation time is calculated as 1-1.5 hours per 100mm thickness.

[0011] Preferably, the forging step includes the following steps: S51: select a large hydraulic press as the forging equipment; S52: perform an upsetting operation on the heated steel ingot under the hydraulic press, and the upsetting ratio is controlled at 2-3. The porosity defects inside the steel ingot are compacted by upsetting to improve the internal structure of the metal; S53: adopt a wide flat anvil high temperature strong pressing method for drawing, the anvil width ratio is controlled at 0.6-0.8, and the amount of each pressing is controlled at 15%-20%. During the drawing process, it is necessary to ensure that each pressed part has a certain anvil width overlap, which is controlled at 10%, and perform a 90° flip operation in time; S54: Use a rounding tool to round the blank on the hydraulic press, and roll the blank into a rough blank close to the shape of the hub; S55: After forging is completed, it is cooled by pit cooling, and the forged hub steel casting is placed in the pit, covered with insulation material, so that the steel casting is slowly cooled to reduce internal stress.

[0012] Preferably, the heat treatment step includes the following steps: S61: normalizing treatment, normalizing the cooled steel casting in a large trolley type resistance furnace, the normalizing temperature is 900-920°C, the holding time is calculated according to the thickness of the steel casting, 1 hour for every 25mm, and air-cooling after normalizing; S62: tempering treatment, tempering treatment is performed after normalizing, the tempering temperature is 600-620°C, the holding time is also determined according to the effective thickness, 2 hours for every 25mm, and air-cooling after tempering.

[0013] Preferably, the step of pouring the smelted molten steel into the casting mold for pouring requires the use of a molten steel pouring device, and the molten steel pouring device includes a base;

[0014] A fixed seat, the fixed seat is fixedly installed on one side of the top of the base, a first servo motor is fixedly installed inside the fixed seat, a threaded rod is fixedly connected to the top of the output shaft of the first servo motor, a moving rod is threadedly engaged with the top of the outer surface of the threaded rod, a connecting block is fixedly installed on the outer surface of the moving rod, a limiting rod is fixedly installed on one side of the top of the fixed seat, a molten steel tank is fixedly installed on one side of the connecting block, a feeding pipe is fixedly installed on the bottom of the molten steel tank, a connecting device is fixedly installed on the top of the outer surface of the feeding pipe, a blocking device is slidably installed inside the connecting device, and a control valve is arranged in the middle of the surface of the feeding pipe;

[0015] A support seat is fixedly mounted on the other side of the top of the base, the conveying device is arranged in the middle of the surface of the support seat, and a casting is arranged on the top of the conveying device.

[0016] Preferably, the connecting device includes a fixed plate, a connecting plate, a movable groove, a threaded rod, a second servo motor, a limit groove and a limit rod, the fixed plate is fixedly installed on the top of the surface of the discharge pipe, the two connecting plates are respectively fixedly installed on both sides of the bottom of the fixed plate, the movable groove is opened on one side of the surface of one of the connecting plates, the threaded rod is rotatably installed inside the movable groove, the second servo motor is fixedly installed on the other side of the surface of the connecting plate, the limit groove is opened on one side of the surface of the other connecting plate, and the limit rod is fixedly installed inside the limit groove.

[0017] Preferably, the blocking device includes a baffle, a threaded block and a limiting slider, the threaded block is threadedly engaged with the outer surface of the threaded rod, the baffle is fixedly installed on one side of the threaded block surface, and the limiting slider is fixedly installed on the other side of the outer surface of the baffle.

[0018] Compared with the related art, the large steel casting forging process provided by the present invention has the following beneficial effects:

[0019] The invention provides a large steel casting forging process. By optimizing the heating process, introducing new forging equipment, improving the forging process and strengthening the quality inspection and other measures, the quality stability of the steel casting is effectively improved, the energy consumption is reduced, the production efficiency and the dimensional accuracy control ability are improved. The high-quality raw materials and advanced smelting technology are adopted to ensure the uniform chemical composition of the steel casting and improve its performance and reliability. The reasonable preheating treatment and forging process reduce the thermal stress and deformation of the steel casting and improve the uniformity and density of its internal organization. The perfect quality inspection system ensures that the quality of the steel casting meets the design requirements and improves the market competitiveness of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1A schematic structural diagram of a first embodiment of a large steel casting forging process provided by the present invention;

[0021] Figure 2 A schematic structural diagram of a second embodiment of a large steel casting forging process provided by the present invention;

[0022] Figure 3 for Figure 2 A schematic cross-sectional view of the support seat shown;

[0023] Figure 4 for Figure 2 The schematic diagram of the connecting device structure shown;

[0024] Figure 5 for Figure 2 A schematic side view of the connecting device shown;

[0025] Figure 6 for Figure 2 Schematic diagram of the blocking device structure shown.

[0026] Numbers in the figure: 1. base, 2. support seat, 3. conveying device, 4. casting, 5. fixed seat, 6. first servo motor, 7. threaded rod, 8. moving rod, 9. threaded hole, 10. limit rod, 11. connecting block, 12. molten steel tank, 13. feeding pipe, 14. connecting device, 141. fixed plate, 142. connecting plate, 143. moving groove, 144. threaded rod, 145. second servo motor, 146. limit groove, 147. limit rod, 15. blocking device, 151. shielding plate, 152. threaded block, 153. limit slider, 16. control valve. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0028] First embodiment

[0029] Please refer to Figure 1 ,in, Figure 1 The schematic diagram of the first embodiment of a large steel casting forging process provided by the present invention is as follows: S1: raw material preparation; S2: smelting; S3: pouring; S4: heating in a heating furnace; S5: forging; S6: heat treatment; S7: quality inspection.

[0030] The raw material preparation step includes the following steps: S11: preparing high-quality G20Mn5N steel ingots; S12: using an ultrasonic flaw detector to perform ultrasonic flaw detection on the steel ingot to check internal defects, using a magnetic particle flaw detector to check the surface and near-surface crack defects of the G20Mn5N steel ingot, and selecting a G20Mn5N steel ingot with a smooth surface.

[0031] The smelting step includes the following steps: S21: placing the G20Mn5N steel ingot into a smelting furnace for smelting, using an electric arc furnace for smelting, and adding alloy elements chromium, nickel and molybdenum to improve the strength, toughness and corrosion resistance of the steel; S22: during the electric arc furnace smelting, electromagnetic stirring is used to evenly distribute the added alloy elements in the molten steel.

[0032] The pouring step comprises the following steps: S31: the smelted molten steel is allowed to stand in a steel ladle, and slag and other impurities mixed into the steel during tapping are allowed to float up and then removed; S32: a steel ingot mold is selected, the integrity and cleanliness of the mold are checked, and a release agent is applied to the inner wall of the mold to facilitate smooth demolding of the steel ingot after forming; S33: the spout of the steel ladle is aligned with the pouring gate of the steel ingot mold, and the spout is slowly opened to allow the molten steel to flow smoothly into the steel ingot mold. During the pouring process, the continuous injection of the molten steel is maintained to avoid interruptions or pauses, prevent stratification defects from occurring inside the steel ingot, and control the pouring speed.

[0033] The heating furnace heating step includes the following steps: S41: using a large gas heating furnace to heat the formed G20Mn5N steel ingot for forging; S42: the initial forging temperature of the G20Mn5N steel is set at 1200-1250°C. During the heating process, it is slowly heated to about 600°C at a speed of 50-100°C / h for insulation, and then continued to be heated to the initial forging temperature at a speed of 100-150°C / h. The insulation time is calculated as 1-1.5 hours per 100mm thickness.

[0034] The forging step comprises the following steps: S51: selecting a large hydraulic press as the forging equipment; S52: performing an upset operation on the heated steel ingot under the hydraulic press, with the upset ratio controlled at 2-3, compacting the porosity defects inside the steel ingot by upset, and improving the internal structure of the metal; S53: adopting a wide flat anvil high temperature strong pressing method for drawing, with the anvil width ratio controlled at 0.6-0.8, and the amount of each pressing being controlled at 15%-20%. During the drawing process, it is necessary to ensure that each pressed part has a certain anvil width overlap, which is controlled at 10%, and perform a 90° flip operation in a timely manner; S54: using a rounding tool to round the blank on the hydraulic press, and rolling the blank into a rough blank close to the shape of the wheel hub; S55: after the forging is completed, cooling is performed by pit cooling, the forged wheel hub steel casting is placed in a pit, covered with insulation material, so that the steel casting is slowly cooled and the internal stress is reduced.

[0035] The heat treatment step includes the following steps: S61: normalizing treatment, normalizing the cooled steel casting in a large trolley type resistance furnace, the normalizing temperature is 900-920°C, the holding time is calculated according to the thickness of the steel casting, 1 hour for every 25mm, and air cooling after normalizing; S62: tempering treatment, tempering treatment is performed after normalizing, the tempering temperature is 600-620°C, the holding time is also determined according to the effective thickness, 2 hours for every 25mm, and air cooling after tempering.

[0036] The working principle of a large steel casting forging process provided by the present invention is as follows:

[0037] When working, first prepare high-quality G20Mn5N steel ingots; S12: Use an ultrasonic flaw detector to perform ultrasonic flaw detection on the steel ingot to check internal defects, use a magnetic particle flaw detector to check the surface and near-surface crack defects of the G20Mn5N steel ingot, and select the G20Mn5N steel ingot with a smooth surface.

[0038] The G20Mn5N steel ingot is placed in a smelting furnace for smelting. The electric arc furnace is used for smelting, and alloy elements chromium, nickel and molybdenum are added to improve the strength, toughness and corrosion resistance of the steel. During the electric arc furnace smelting, electromagnetic stirring is used to evenly distribute the added alloy elements in the molten steel.

[0039] The smelted molten steel is left to stand in the ladle to allow the slag and other impurities mixed into the steel during tapping to float up and then be removed; select the ingot mold, check the integrity and cleanliness of the mold, and apply a release agent to the inner wall of the mold to facilitate smooth demoulding after the ingot is formed; align the spout of the ladle with the pouring gate of the ingot mold, slowly open the spout, and allow the molten steel to flow smoothly into the ingot mold. During the pouring process, maintain continuous injection of the molten steel to avoid interruptions or pauses, prevent stratification defects inside the ingot, and control the pouring speed.

[0040] A large gas heating furnace is used to heat the formed G20Mn5N steel ingot for forging; the initial forging temperature of G20Mn5N steel is set at 1200-1250℃. During the heating process, it is slowly heated to about 600℃ at a speed of 50-100℃ / h for insulation, and then continued to be heated to the initial forging temperature at a speed of 100-150℃ / h. The insulation time is calculated as 1-1.5 hours per 100mm thickness.

[0041] A large hydraulic press is used as forging equipment; the heated steel ingot is upset under the hydraulic press, and the upsetting ratio is controlled at 2-3. The porosity defects inside the steel ingot are compacted by upsetting, and the internal structure of the metal is improved; the wide flat anvil high temperature strong pressing method is used for drawing, and the anvil width ratio is controlled at 0.6-0.8, and the amount of each pressing is controlled at 15%-20%. During the drawing process, it is necessary to ensure that each pressed part has a certain anvil width overlap, which is controlled at 10%, and a 90° flip operation is performed in time; the billet is rounded on the hydraulic press using a rounding tool, and the billet is rolled into a rough billet close to the shape of the hub; after forging, it is cooled by pit cooling, and the forged hub steel casting is placed in a pit, covered with insulation materials, so that the steel casting is cooled slowly to reduce internal stress.

[0042] Normalizing treatment: the cooled steel castings are normalized in a large trolley-type resistance furnace at a temperature of 900-920°C. The holding time is calculated according to the thickness of the steel castings, with 1 hour of holding for every 25mm. After normalizing, they are taken out of the furnace and air-cooled. Tempering treatment: tempering treatment is carried out after normalizing. The tempering temperature is 600-620°C. The holding time is also determined according to the effective thickness, with 2 hours of holding for every 25mm. After tempering, they are taken out of the furnace and air-cooled.

[0043] Compared with the related art, the large steel casting forging process provided by the present invention has the following beneficial effects:

[0044] The invention provides a large steel casting forging process. By optimizing the heating process, introducing new forging equipment, improving the forging process and strengthening the quality inspection and other measures, the quality stability of the steel casting is effectively improved, the energy consumption is reduced, the production efficiency and the dimensional accuracy control ability are improved. The high-quality raw materials and advanced smelting technology are adopted to ensure the uniform chemical composition of the steel casting and improve its performance and reliability. The reasonable preheating treatment and forging process reduce the thermal stress and deformation of the steel casting and improve the uniformity and density of its internal organization. The perfect quality inspection system ensures that the quality of the steel casting meets the design requirements and improves the market competitiveness of the product.

[0045] Second embodiment

[0046] Please refer to Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 Based on the large steel casting forging process provided by the first embodiment of the present application, the second embodiment of the present application proposes another large steel casting forging process. The second embodiment is only a preferred embodiment of the first embodiment, and the implementation of the second embodiment will not affect the independent implementation of the first embodiment.

[0047] Specifically, the second embodiment of the present application provides a large steel casting forging process that is different in that, in a large steel casting forging process, the step of pouring the molten steel into the casting mold for pouring requires the use of a molten steel pouring device, and the molten steel pouring device includes a base 1;

[0048] A fixed seat 5, the fixed seat 5 is fixedly installed on one side of the top of the base 1, a first servo motor 6 is fixedly installed inside the fixed seat 5, a threaded rod 7 is fixedly connected to the top of the output shaft of the first servo motor 6, a moving rod 8 is threadedly engaged with the top of the outer surface of the threaded rod 7, a connecting block 11 is fixedly installed on the outer surface of the moving rod 8, a limiting rod 10 is fixedly installed on one side of the top of the fixed seat 5, a molten steel tank 12 is fixedly installed on one side of the connecting block 11, a feeding pipe 13 is fixedly installed on the bottom of the molten steel tank 12, a connecting device 14 is fixedly installed on the top of the outer surface of the feeding pipe 13, a blocking device 15 is slidably installed inside the connecting device 14, and a control valve 16 is provided in the middle of the surface of the feeding pipe 13;

[0049] The support seat 2 is fixedly mounted on the other side of the top of the base 1 , the conveying device 3 is arranged in the middle of the surface of the support seat 2 , and a casting 4 is arranged on the top of the conveying device 3 .

[0050] The connecting device 14 includes a fixed plate 141, a connecting plate 142, a movable groove 143, a threaded rod 144, a second servo motor 145, a limit groove 146 and a limit rod 147. The fixed plate 141 is fixedly installed on the top of the surface of the discharge tube 13, and the two connecting plates 142 are respectively fixedly installed on both sides of the bottom of the fixed plate 141. The movable groove 143 is opened on one side of the surface of one of the connecting plates 142, and the threaded rod 144 is rotatably installed inside the movable groove 143. The second servo motor 145 is fixedly installed on the other side of the surface of the connecting plate 142, and the limit groove 146 is opened on one side of the surface of the other connecting plate 142. The limit rod 147 is fixedly installed inside the limit groove 146.

[0051] The blocking device 15 includes a baffle plate 151, a threaded block 152 and a limiting slider 153. The threaded block 152 is threadedly engaged with the outer surface of the threaded rod 144, the baffle plate 151 is fixedly installed on one side of the surface of the threaded block 152, and the limiting slider 153 is fixedly installed on the other side of the outer surface of the baffle plate 151.

[0052] The working principle of a large steel casting forging process provided by the present invention is as follows:

[0053] During operation, first, an external power source controls the output shaft of the second servo motor 145 to rotate and drive the threaded rod 144 to rotate. The threaded rod 144 rotates to engage the threaded block 152 to move, and the baffle plate 151 is adjusted to move at the bottom of the discharge pipe 13 to adjust the discharge range of the discharge pipe 13.

[0054] For example, when the casting 4 is almost fully poured, the baffle 151 is adjusted to move toward the center of the lower feeding pipe 13 to reduce the feeding range of the lower feeding pipe 13, maintain the feeding accuracy, and prevent the molten steel from overflowing the casting 4. After the casting is fully poured, the baffle 151 blocks the bottom of the lower feeding pipe 13, and then the control valve 16 is closed to prevent the molten steel from leaking.

[0055] Compared with the related art, the large steel casting forging process provided by the present invention has the following beneficial effects:

[0056] The present invention provides a large steel casting forging process, which controls the output shaft of the second servo motor 145 to rotate through an external power supply to drive the threaded rod 144 to rotate. The threaded rod 144 rotates to engage the threaded block 152 to move, and the baffle plate 151 is adjusted to move at the bottom of the discharge pipe 13 to adjust the discharge range of the discharge pipe 13. The device has a simple structure and strong practicality. The operator can adjust the position of the baffle plate 151 according to the volume cast inside the casting 4, and can quickly block the discharge diameter of the discharge pipe 13 to prevent the residual liquid in the discharge pipe 13 from continuing to be discharged after the control valve 16 is closed, thereby maintaining the accuracy of the liquid poured inside the casting 4, preventing the poured liquid from overflowing the casting 4, and improving the practicality of the device.

[0057] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A large steel casting forging process, characterized in that: The following steps are involved: S1: Raw material preparation; S2: Melting; S3: Casting; S4: Heating in a heating furnace; S5: Forging; S6: Heat treatment; S7: Quality inspection.

2. A large steel casting forging process according to claim 1, characterized in that: The raw material preparation steps The method comprises the following steps: S11: preparing high-quality G20Mn5N steel ingots; S12: performing ultrasonic flaw detection on the steel ingots by using an ultrasonic flaw detector to check internal defects, checking surface and near-surface crack defects of the G20Mn5N steel ingots by using a magnetic particle flaw detector, and selecting G20Mn5N steel ingots with smooth surfaces.

3. A large steel casting forging process according to claim 1, characterized in that: The smelting step The method comprises the following steps: S21: placing a G20Mn5N steel ingot into a smelting furnace for smelting, adopting an electric arc furnace for smelting, and adding alloy elements of chromium, nickel and molybdenum to improve the strength, toughness and corrosion resistance of the steel; S22: in the electric arc furnace smelting, using electromagnetic stirring to evenly distribute the added alloy elements in the molten steel.

4. A large steel casting forging process according to claim 1, characterized in that: The pouring step The method comprises the following steps: S31: the smelted molten steel is allowed to stand in a steel ladle, and slag and other impurities mixed into the steel during tapping are allowed to float up and then removed; S32: a steel ingot mold is selected, the integrity and cleanliness of the mold are checked, and a release agent is applied to the inner wall of the mold to facilitate smooth demoulding of the steel ingot after forming; S33: the spout of the steel ladle is aligned with the pouring port of the steel ingot mold, and the spout is slowly opened to allow the molten steel to flow smoothly into the steel ingot mold. During the pouring process, the continuous injection of the molten steel is maintained to avoid interruptions or pauses, prevent stratification defects from occurring inside the steel ingot, and control the pouring speed.

5. A large steel casting forging process according to claim 1, characterized in that: The heating furnace heating step The method comprises the following steps: S41: using a large gas heating furnace to heat the formed G20Mn5N steel ingot for forging; S42: the initial forging temperature of the G20Mn5N steel is set at 1200-1250°C, and during the heating process, it is slowly heated to about 600°C at a speed of 50-100°C / h for insulation, and then continues to be heated to the initial forging temperature at a speed of 100-150°C / h, and the insulation time is calculated as 1-1.5 hours per 100mm thickness.

6. A large steel casting forging process according to claim 1, characterized in that: The forging step The method comprises the following steps: S51: selecting a large hydraulic press as forging equipment; S52: performing an upset operation on the heated steel ingot under the hydraulic press, with the upset ratio controlled at 2-3, compacting the porosity defects inside the steel ingot through the upset, and improving the internal structure of the metal; S53: adopting a wide flat anvil high temperature strong pressing method for drawing, with the anvil width ratio controlled at 0.6-0.8, and the pressing amount each time controlled at 15%-20%. During the drawing process, it is necessary to ensure that each pressed part has a certain anvil width overlap, which is controlled at 10%, and perform a 90° flip operation in due time; S54: using a rounding tool to round the blank on the hydraulic press, and rolling the blank into a rough blank close to the shape of a wheel hub; S55: after the forging is completed, cooling is performed by a pit cooling method, the forged wheel hub steel casting is placed in a pit, covered with a heat preservation material, so that the steel casting is slowly cooled and the internal stress is reduced.

7. A large steel casting forging process according to claim 1, characterized in that: The heat treatment step includes the following steps: S61: normalizing treatment, normalizing the cooled steel casting in a large trolley type resistance furnace, the normalizing temperature is 900-920°C, the holding time is calculated according to the thickness of the steel casting, 1 hour for every 25mm, and air cooling after normalizing; S62: tempering treatment, tempering treatment is performed after normalizing, the tempering temperature is 600-620°C, the holding time is also determined according to the effective thickness, 2 hours for every 25mm, and air cooling after tempering.

8. A large steel casting forging process according to claim 1, characterized in that: The step of pouring the smelted molten steel into the casting mold for pouring requires the use of a molten steel pouring device, and the molten steel pouring device includes a base; A fixed seat, the fixed seat is fixedly installed on one side of the top of the base, a first servo motor is fixedly installed inside the fixed seat, a threaded rod is fixedly connected to the top of the output shaft of the first servo motor, a moving rod is threadedly engaged with the top of the outer surface of the threaded rod, a connecting block is fixedly installed on the outer surface of the moving rod, a limiting rod is fixedly installed on one side of the top of the fixed seat, a molten steel tank is fixedly installed on one side of the connecting block, a feeding pipe is fixedly installed on the bottom of the molten steel tank, a connecting device is fixedly installed on the top of the outer surface of the feeding pipe, a blocking device is slidably installed inside the connecting device, and a control valve is arranged in the middle of the surface of the feeding pipe; A support seat is fixedly mounted on the other side of the top of the base, the conveying device is arranged in the middle of the surface of the support seat, and a casting is arranged on the top of the conveying device.

9. A large steel casting forging process according to claim 8, characterized in that: The connecting device includes a fixed plate, a connecting plate, a movable groove, a threaded rod, a second servo motor, a limit groove and a limit rod. The fixed plate is fixedly installed on the top of the surface of the discharge pipe, and the two connecting plates are respectively fixedly installed on both sides of the bottom of the fixed plate. The movable groove is opened on one side of the surface of one of the connecting plates, and the threaded rod is rotatably installed inside the movable groove. The second servo motor is fixedly installed on the other side of the surface of the connecting plate, the limit groove is opened on one side of the surface of the other connecting plate, and the limit rod is fixedly installed inside the limit groove.

10. A large steel casting forging process according to claim 8, characterized in that: The blocking device includes a baffle, a threaded block and a limiting slider, wherein the threaded block is threadedly engaged with the outer surface of the threaded rod, the baffle is fixedly installed on one side of the threaded block surface, and the limiting slider is fixedly installed on the other side of the outer surface of the baffle.

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