Production method of supporting roll steel

Abstract

The invention relates to a production method of supporting roll steel, belongs to the field of smelting industry, and solves the problems that the existing supporting roll steel is high in cost, and the shrinkage porosity of a core shrinkage cavity is serious. The production method of the supporting roller steel comprises the following steps: smelting a supporting roller steel ingot raw material, deoxidizing, desulfurizing and refining, adjusting alloy components to obtain a first part of supporting roller molten steel, tapping, pouring in vacuum, and solidifying to obtain a first part of supporting roller steel ingot solidified blank shell and liquid molten steel in the blank shell; the method comprises the following steps: smelting, deoxidizing, desulfurizing and refining raw materials of a supporting roll steel ingot, adjusting alloy components to obtain a second part of supporting roll molten steel, tapping, uniformly mixing the second part of supporting roll molten steel with liquid molten steel in a solidified blank shell of the first part of supporting roll steel ingot, carrying out vacuum pouring and solidification to obtain a complete supporting roll steel ingot, demolding, and cutting off a water gap to obtain the supporting roll steel ingot. Forging forming, dead head cutting, heat treatment and machining are carried out to obtain the supporting roll steel. The molten steel components of the first part supporting roller and the molten steel components of the second part supporting roller are different.

Description

Technical Field

[0001] The invention relates to the technical field of smelting industry, and in particular to a production method of support roller steel. Background Art

[0002] The backup roll is an important part of the rolling mill, used to support the working roll or the intermediate roll to prevent the working roll from bending and deformation, which may affect the output and quality of the plate and strip. The backup roll has the characteristics of high wear resistance, good anti-stripping and strong anti-accident performance.

[0003] As cold and hot rolling mills continue to develop in the direction of high speed, large-scale and high precision, the hardness of the working rolls of cold and hot rolling mills has generally increased, and higher and higher requirements have been put forward for the supporting rolls that match them. The Cr content in Cr4 and Cr5 supporting roll steels is increased to 4% to 5%, the carbon content is 0.45% to 0.55%, and trace V elements are added to refine the steel type of the core structure of the supporting roll. The wear resistance and spalling resistance of the rolls of this material are significantly improved. The hardenability, fatigue resistance and accident resistance of the supporting rolls of this material are significantly improved compared with the supporting rolls of previous materials. It has gradually become the leading steel for high-performance forged steel supporting rolls for modern plate and strip rolling mills.

[0004] The existing production process of Cr4 and Cr5 series backup roller steel ingots is: raw materials → steelmaking (electric furnace smelting, ladle refining) → vacuum ingot casting → forging → heat treatment → cold processing → physical and chemical testing. Due to the high alloy content of this series of backup rollers, the complex production process, high production cost, and the serious shrinkage and porosity in the core of the prepared backup roller steel ingots, it is urgent to optimize the existing production process of Cr4 and Cr5 series backup roller steel to reduce its production cost. Summary of the invention

[0005] In view of the above analysis, an embodiment of the present invention aims to provide a method for producing support roller steel, which is used to at least solve one of the following problems existing in the production process of existing Cr4 and Cr5 series support roller steel ingots: 1. The production and manufacturing cost of existing Cr4 and Cr5 series support roller steel ingots is high; 2. The support roller steel ingots prepared by the existing Cr4 and Cr5 series support roller steel ingots have serious shrinkage cavities and shrinkage in the core.

[0006] An embodiment of the present invention provides a method for producing support roller steel, comprising the following steps:

[0007] S1: smelting, deoxidation, desulfurization and refining of the raw materials of the support roller steel ingot, adjusting the alloy composition in sequence, obtaining the first part of the support roller molten steel, and tapping the steel;

[0008] S2: vacuum pouring and solidifying the first portion of the molten steel for the support roller to obtain a solidified shell of the first portion of the support roller steel ingot and liquid molten steel in the solidified shell;

[0009] S3: smelting, deoxidation and desulfurization refining, and adjusting the alloy composition of the raw materials of the support roller steel ingot in sequence to obtain the second part of the support roller molten steel, and tapping the steel;

[0010] S4: vacuum pouring the second part of the molten steel for the backup roller into the solidified shell of the first part of the backup roller steel ingot, mixing the second part of the molten steel for the backup roller with the liquid molten steel in the solidified shell in step S2, and continuing to fill the ingot body and the ingot riser, solidifying, and obtaining a complete backup roller steel ingot;

[0011] S5: demoulding the complete support roller steel ingot, cutting off the nozzle, forging, cutting off the riser, heat treatment, and machining to obtain the support roller steel;

[0012] There is a difference between the composition of the molten steel of the first backup roll and the composition of the molten steel of the second backup roll.

[0013] Further, step S2 includes:

[0014] S21: Arrange the steel ingot mold in a 150-350t vacuum chamber, and keep the vacuum degree of the vacuum chamber ≤ 0.5 Torr before pouring;

[0015] S22: The ingot casting uses a 60-100t tundish equipped with an argon-blown stopper rod. The first part of the support roll molten steel refining ladle is hoisted by a 200-350t overhead crane to drain the refining ladle. Then the first part of the support roll molten steel refining ladle is hoisted and placed above the tundish. The first part of the support roll molten steel is poured into the tundish.

[0016] S23: lift the argon blowing plug rod of the tundish, blow argon into it, and start pouring the tundish. After the first part of the molten steel of the support roller is poured in the tundish for 3 to 5 minutes, measure the temperature of the molten steel in the tundish to ensure that the temperature of the molten steel in the tundish is controlled at 1530℃~1550℃. The molten steel and argon gas are mixed and enter the ingot mold in the vacuum chamber through the tundish water inlet;

[0017] S24: After the tundish pouring is completed, the vacuum is destroyed, and after the vacuum chamber returns to atmospheric pressure, 0.8-1.2 kg / t of heat preservation agent is added for solidification to obtain a solidified shell of the support roller ingot and liquid steel in the solidified shell.

[0018] Further, step S4 includes:

[0019] S41: Casting is performed in the vacuum chamber of step S21, the ingot mold remains the same, and the vacuum degree of the vacuum chamber is maintained at ≤0.5 Torr before casting;

[0020] S42: The second part of the molten steel refining ladle for the supporting roller is hoisted by a 200-350t overhead crane, and the molten steel refining ladle for the supporting roller is drained outside the refining ladle, and then the second part of the molten steel refining ladle for the supporting roller is hoisted and placed on the vacuum cover of the vacuum chamber, and the vacuum is evacuated to a vacuum degree of ≤0.5 Torr;

[0021] S43: The refining ladle begins pouring, and argon is not blown into the refining ladle water port. The second part of the support roller molten steel refining ladle is poured within 0 to 3 minutes. The temperature of the molten steel in the refining ladle is measured to ensure that the temperature of the molten steel in the refining ladle is controlled at 1590 to 1610°C. The molten steel enters the ingot mold in the vacuum chamber through the refining ladle water port;

[0022] S44: After the pouring is completed, the vacuum is destroyed. After the vacuum chamber returns to atmospheric pressure, 1.8-2.2 kg / t of exothermic agent and 0.8-1.2 kg / t of heat-insulating agent are added to the molten steel surface in the ingot mold, and solidified to obtain a complete support roller ingot.

[0023] Furthermore, the composition of the molten steel of the first part of the supporting roller includes, by mass percentage, the following: C: 0.45%-0.55%, Si: 0.20%-0.70%, Mn: 0.40%-0.70%, Cr: 4.50%-5.50%, Ni: 0.40%-0.50%, Mo: 0.90%-1.10%, V: 0.35%-0.45%, S≤0.002%, O≤0.0025%, and the remainder is Fe.

[0024] Furthermore, the composition of the molten steel of the second part of the supporting roller includes, by mass percentage, the following: C: 0.15%-0.25%, Si: 0.20%-0.70%, Mn: 0.20%-0.70%, Cr: 0.50%-1.50%, Ni: 0.20%-0.50%, Mo: 0.10%-1.10%, V: 0.05%-0.45%, S≤0.002%, O≤0.0025%, and the remainder is Fe.

[0025] Furthermore, the weight of the first portion of the molten steel for the backup roller accounts for 87% to 89% of the weight of the backup roller steel ingot, and the weight of the second portion of the molten steel for the backup roller accounts for 11% to 13% of the weight of the backup roller steel ingot.

[0026] Furthermore, in step S1, the steel tapping temperature is 1570-1590°C.

[0027] Furthermore, in step S2, the coagulation time is 4 to 8 hours.

[0028] Furthermore, in step S3, the steel tapping temperature is 1620-1640°C.

[0029] Furthermore, in step S4, the coagulation time is 36 to 45 hours.

[0030] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0031] 1. The present invention uses conventional production equipment to sequentially smelt, deoxidize and desulfurize the raw materials of the support roller steel, adjust the alloy, and perform two interval vacuum castings to obtain the support roller steel ingot. The conventionally smelted and cast support roller steel ingot usually has a riser ratio of 20% to 21% and an ingot body ratio of 76 to 78%. The present invention reduces the riser weight required for the shrinkage-feeding steel ingot by performing two vacuum castings at an interval of 4 to 8 hours, increasing the temperature of the second part of the poured molten steel and adjusting the alloy composition of the molten steel. The same mold is used to produce support roller steel with the same ingot body weight. Compared with the conventional method, the method of the present invention can reduce the riser ratio to 14% to 15%, so the ingot body ratio is increased to 81% to 83%, reducing the weight of the steel ingot required to produce the same specification of support rollers, and reducing the manufacturing cost.

[0032] 2. The present invention uses two interval vacuum pourings to dilute the alloy components in the core of the steel ingot during the second pouring, and increases the temperature of the molten steel in the core, thereby improving the conditions for shrinkage compensation of the molten steel before the secondary shrinkage and porosity of the ingot body is formed, and improving the shrinkage and porosity of the core of the supporting roller steel ingot.

[0033] 3. The present invention ensures the performance requirements of the working layer of the support roller by ensuring the composition of the first part of the cast molten steel, while reducing the alloy composition of the second part of the cast molten steel, reducing the amount of alloy used and reducing the manufacturing cost of the support roller.

[0034] 4. The support roller product produced by the method of the present invention has the outer layer material with high alloy content, which well obtains the strength required by the working layer of the support roller; while the core material has low alloy content, which can obtain good toughness and improve the fracture resistance of the support roller.

[0035] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0037] Figure 1 It is a schematic diagram of the implementation process of the method of the present invention;

[0038] Figure 2 Schematic diagram of shrinkage and shrinkage cavity of the support roller steel ingot of Example 1 of the present invention;

[0039] Figure 3Schematic diagram of shrinkage and shrinkage cavity of the support roller steel ingot of comparative example 1 of the present invention.

[0040] Figure numerals: 1-steel ingot riser, 2-steel ingot body, 3-shrinkage hole in the center of the steel ingot, 4-steel ingot nozzle; 5-first part of the molten steel for the supporting roller; 6-solidified shell of the supporting roller steel ingot; 7-liquid steel in the solidified shell; 8-second part of the molten steel for the supporting roller and the liquid steel in the solidified shell. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0042] The present invention provides a method for producing backup roller steel, comprising the following steps:

[0043] S1: smelting, deoxidation, desulfurization and refining of the raw materials of the support roller steel ingot, adjusting the alloy composition in sequence, obtaining the first part of the support roller molten steel, and tapping the steel;

[0044] S2: vacuum pouring and solidifying the first portion of the molten steel for the support roller to obtain a solidified shell of the first portion of the support roller steel ingot and liquid molten steel in the solidified shell;

[0045] S3: smelting, deoxidation and desulfurization refining, and adjusting the alloy composition of the raw materials of the support roller steel ingot in sequence to obtain the second part of the support roller molten steel, and tapping the steel;

[0046] S4: vacuum pouring the second part of the molten steel for the backup roller into the solidified shell of the first part of the backup roller steel ingot, mixing the second part of the molten steel for the backup roller with the liquid molten steel in the solidified shell in step S2, and continuing to fill the ingot body and the ingot riser, solidifying, and obtaining a complete backup roller steel ingot;

[0047] S5: demoulding the complete support roller steel ingot, cutting off the nozzle, forging, cutting off the riser, heat treatment, and machining to obtain the support roller steel;

[0048] There is a difference between the composition of the molten steel of the first backup roll and the composition of the molten steel of the second backup roll.

[0049] It should be noted that the above-mentioned production method of support roller steel is particularly suitable for smelting large steel ingots, and the weight of the large steel ingots is 150-300 tons.

[0050] Specifically, in step S1, the weight of the first part of the molten steel of the backup roller steel accounts for 87% to 89% of the weight of the backup roller steel ingot, and its components, by mass percentage, include: C: 0.45% to 0.55%, Si: 0.20% to 0.70%, Mn: 0.40% to 0.70%, Cr: 4.50% to 5.50%, Ni: 0.40% to 0.50%, Mo: 0.90% to 1.10%, V: 0.35% to 0.45%, S≤0.002%, O≤0.0025%, and the balance is Fe;

[0051] Specifically, in step S1, the first part of the molten steel for the support roller needs to be able to fill the water inlet and the body of the support roller steel ingot, and ensure that the filling height of the riser is 100-200 mm; the weight of the first part of the molten steel for the support roller = the weight of part of the steel ingot body + the water inlet + part of the riser (height 100-200 mm), that is, the weight of the first part of the molten steel for the support roller accounts for 87%-89% of the weight of the support roller steel ingot. After the first part of the molten steel for the support roller is qualified, the tapping temperature of the molten steel is 1570-1590°C.

[0052] It should be noted that, due to the limitation of the existing ladle capacity, when producing large steel ingots of 150 to 300 tons, it is necessary to divide the first part of the molten steel for the support roller into 2 to 3 parts according to the capacity of the existing ladle, and perform smelting, deoxidation and desulfurization refining, and adjustment of alloy composition respectively. The sum of the molten steel is the first part of the molten steel for the support roller, and the sum of the weights of the molten steel accounts for 87% to 89% of the weight of the support roller ingot. The composition of each part of the molten steel satisfies the mass percentage of the composition described in step S1 respectively. Subsequently, vacuum casting and solidification are performed respectively to obtain the solidified shell of the support roller ingot and the liquid molten steel in the solidified shell.

[0053] Specifically, in step S2, the first part of the molten steel for the backup roller is vacuum poured, and after solidification for 4 to 8 hours, a solidified shell of the backup roller ingot and liquid molten steel in the solidified shell are obtained; the thickness of the solidified shell of the backup roller ingot is 400 to 500 mm; specifically, the following steps are included:

[0054] S21: Arrange the steel ingot mold in a 150-350t vacuum chamber, and keep the vacuum degree of the vacuum chamber ≤ 0.5 Torr before pouring;

[0055] S22: The ingot casting uses a 60-100t tundish equipped with an argon-blown stopper rod. The first part of the support roll molten steel refining ladle is hoisted by a 200-350t overhead crane to drain the refining ladle. Then the first part of the support roll molten steel refining ladle is hoisted and placed above the tundish. The first part of the support roll molten steel is poured into the tundish.

[0056] S23: lift the argon blowing plug rod of the tundish, blow argon into it, and start pouring the tundish. After the first part of the molten steel of the support roller is poured in the tundish for 3 to 5 minutes, measure the temperature of the molten steel in the tundish to ensure that the temperature of the molten steel in the tundish is controlled at 1530℃~1550℃. The molten steel and argon gas are mixed and enter the ingot mold in the vacuum chamber through the tundish water inlet;

[0057] S24: After the tundish pouring is completed, the vacuum is destroyed. After the vacuum chamber returns to atmospheric pressure, 0.8-1.2 kg / t of heat preservation agent is added and solidified for 4-8 hours to obtain the solidified shell of the support roller ingot and the liquid steel in the solidified shell.

[0058] It should be noted that in step S23, if the pouring temperature of molten steel is too high, the shrinkage and looseness of the core of the steel ingot will increase. If the temperature of molten steel is too low, the inclusions in the molten steel cannot float up and be removed during the solidification process. Therefore, the temperature of molten steel in the tundish should be controlled at 1530℃~1550℃. Argon gas is blown into the water inlet of the tundish, and the gas expands under vacuum to explode the molten steel stream, so that the molten steel stream is drip-shaped when poured under vacuum. This is because the molten steel stream forms a drip-shaped stream, and the contact area increases under vacuum. , which is more conducive to removing harmful gases, and the molten steel surface is relatively weak from concentrated impact, the molten steel surface is more stable, and the surface quality of the ingot is better; the pouring speed is 5-7t / min; the thickness of the solidified shell of the support roller ingot obtained in step S24 is 400-500mm, and the solidified shell of this thickness will serve as a 60-100mm thick working layer of the support roller after subsequent forging and heat treatment; after solidification for 4-8h, due to the short solidification time, the solidified shell (i.e., the core of the ingot) is still liquid molten steel.

[0059] Specifically, in step S3, the raw material of the backup roller steel is smelted, deoxidized and desulfurized, refined, and the alloy composition is adjusted in sequence to obtain the second part of the backup roller molten steel, and the steel is tapped. The weight of the second part of the backup roller steel molten steel accounts for 11% to 13% of the weight of the backup roller steel, and its components, by mass percentage, include: C: 0.15% to 0.25%, Si: 0.20% to 0.70%, Mn: 0.20% to 0.70%, Cr: 0.50% to 1.50%, Ni: 0.20% to 0.50%, Mo: 0.10% to 1.10%, V: 0.05% to 0.45%, S≤0.002%, O≤0.0025%, and the remainder is Fe; after the second part of the backup roller molten steel has qualified components, the tapping temperature of the molten steel is 1620 to 1640°C.

[0060] Specifically, in step S4, the second part of the molten steel for the backup roller is vacuum poured into the solidified shell of the first part of the backup roller steel ingot, the second part of the molten steel for the backup roller is mixed with the liquid molten steel in the solidified shell in step S2, and the ingot body and the ingot riser are continuously filled to obtain a complete backup roller steel ingot; comprising:

[0061] S41: Casting is performed in the vacuum chamber of step S21, the ingot mold remains the same, and the vacuum degree of the vacuum chamber is maintained at ≤0.5 Torr before casting;

[0062] S42: The second part of the molten steel refining ladle for the supporting roller is hoisted by a 200-350t overhead crane, and the molten steel refining ladle for the supporting roller is drained outside the refining ladle, and then the second part of the molten steel refining ladle for the supporting roller is hoisted and placed on the vacuum cover of the vacuum chamber, and the vacuum is evacuated to a vacuum degree of ≤0.5 Torr;

[0063] S43: The refining ladle begins pouring, and argon is not blown into the refining ladle water port. The second part of the support roller molten steel refining ladle is poured within 0 to 3 minutes. The temperature of the molten steel in the refining ladle is measured to ensure that the temperature of the molten steel in the refining ladle is controlled at 1590 to 1610°C. The molten steel enters the ingot mold in the vacuum chamber through the refining ladle water port;

[0064] S44: After the pouring is completed, the vacuum is destroyed. After the vacuum chamber returns to atmospheric pressure, 1.8-2.2 kg / t of heating agent and 0.8-1.2 kg / t of heat preservation agent are added to the molten steel surface in the ingot mold. After the ingot is completely solidified, a complete support roller ingot is obtained.

[0065] It should be noted that in step S42, the second part of the molten steel for the backup rolls in the refining ladle can also be poured into the tundish, and the tundish is used for pouring without blowing argon into the tundish nozzle. In this step, the refining ladle or the tundish is used for direct pouring, and argon is not blown into the nozzle, so that the molten steel stream of the second part of the molten steel for the backup rolls is in a state of non-dispersed streams under a vacuum state. In this state, the molten steel stream has a strong impact force and can break the surface of the solidified shell of the first part of the backup roll ingot, and the impact depth is deeper, which is more conducive to mixing the second part of the molten steel for the backup rolls with the liquid molten steel in the solidified shell in step S2.

[0066] It should be noted that after the first part of the molten steel for the supporting roller solidifies for 4 to 8 hours, the temperature of the molten steel in the solidified shell of the first part of the supporting roller ingot (i.e., the core of the ingot) is relatively low, and the pouring temperature of the second part of the molten steel for the supporting roller needs to be increased to break open the surface of the solidified shell of the first part of the supporting roller ingot. If the pouring temperature of the molten steel for the second part of the supporting roller is too high, the solidified shell of the first part of the supporting roller ingot will melt and thin too much, and the requirement of the thickness of the supporting roller working layer will not be met; if the pouring temperature of the molten steel for the second part of the supporting roller is too high or too low, it will be difficult to break open the surface of the solidified shell of the first part of the supporting roller ingot, and the purpose of heating the liquid molten steel in the solidified shell in step S2 cannot be achieved. Therefore, the pouring temperature of the molten steel for the second part of the supporting roller is 1590 to 1610°C. In step S44, after the vacuum chamber returns to atmospheric pressure, 1.8-2.2 kg / t of heat-generating agent and 0.8-1.2 kg / t of heat-insulating agent are added to the liquid level of molten steel in the ingot mold. The heat-generating agent burns to generate heat, providing heat for the molten steel in the riser, slowing down the solidification time of the riser and achieving better shrinkage compensation effect in the core of the ingot. The heat-insulating agent further keeps the heat of the heat-generating agent warm. After solidification for 36-45 hours, the ingot is completely solidified to obtain a complete supporting roller ingot.

[0067] The method of the present invention utilizes conventional production equipment to sequentially perform smelting, deoxidation and desulfurization refining and two interval vacuum casting on the raw materials of the support roller steel. The support roller steel ingots of conventional smelting and casting usually have a riser ratio of 20% to 21% and an ingot body ratio of 76 to 78%. The support roller steel with the same ingot body weight is produced by using the same mold. Compared with the existing method, the method of the present invention can reduce the riser ratio to 14% to 15%, and the corresponding ingot body ratio is increased to 81% to 83%, thereby reducing the amount of alloy used and reducing the manufacturing cost. At the same time, the quality of the support roller steel produced is equivalent to that of the traditional method.

[0068] Example 1

[0069] In this embodiment, a certain backup roller steel is produced, the weight of a complete backup roller steel ingot is 153 tons, and the weight of the ingot body (that is, the backup roller steel finally obtained) is about 125.23 tons.

[0070] The following steps are involved:

[0071] S1: The raw materials of the support roller steel are smelted in a 100t electric furnace and a 40t electric furnace in turn to obtain 129t of molten steel, which is then added to a 160t refining furnace for deoxidation and desulfurization refining, and the alloy composition is adjusted to obtain 136t of the first part of the support roller molten steel, with a tapping temperature of 1573℃;

[0072] The weight of the first part of the molten steel of the backup roller steel accounts for 88.89% of the weight of the backup roller steel, and its composition by mass percentage includes: C: 0.51%, Si: 0.43%, Mn: 0.54%, Cr: 5.13%, Ni: 0.47%, Mo: 1.06%, V: 0.39%, S: 0.002%, O: 0.0023%, and the balance is Fe;

[0073] S2: The first part of the molten steel for the support roller is vacuum poured and solidified for 5 hours to obtain a solidified shell (thickness 400 mm) of the support roller ingot and liquid molten steel in the shell, including:

[0074] S21: Arrange the steel ingot mold in the 350t vacuum chamber, and keep the vacuum degree of the vacuum chamber less than 0.5 Torr before pouring;

[0075] S22: A 60t tundish is used for ingot casting and equipped with an argon-blowing stopper rod. The first part of the support roll molten steel refining ladle is hoisted by a 350t overhead crane to drain the refining ladle. Then the first part of the support roll molten steel refining ladle is hoisted and placed above the tundish. The first part of the support roll molten steel is poured into the tundish.

[0076] S23: lift the argon blowing plug rod of the tundish, blow argon into it, and start pouring the tundish. After the first part of the molten steel of the support roller is poured in the tundish for 4 minutes, the temperature of the molten steel in the tundish is measured, and the temperature is 1545℃. The molten steel and argon gas are mixed and enter the steel ingot mold in the vacuum chamber through the tundish water inlet;

[0077] S24: After the tundish pouring is completed, the vacuum is destroyed. After the vacuum chamber returns to atmospheric pressure, 136 kg of heat preservation agent is added and solidified for 5 hours to obtain a solidified shell (thickness 400 mm) of the support roller ingot and liquid steel in the shell.

[0078] S3: Using a 40t electric furnace, the raw materials of the support roller steel are smelted in sequence to obtain 17t of molten steel, which is then added to a 40t refining furnace for deoxidation and desulfurization refining, and the alloy composition is adjusted to obtain 17t of the second part of molten steel for the support roller, with a tapping temperature of 1634°C;

[0079] The weight of the second part of the backup roller steel molten steel accounts for 11.11% of the weight of the backup roller steel, and its composition by mass percentage includes: C: 0.17%, Si: 0.22%, Mn: 0.35%, Cr: 0.78%, Ni: 0.43%, Mo: 0.91%, V: 0.05%, S: 0.002%, O: 0.0025%, and the balance is Fe;

[0080] S4: vacuum pouring the second part of the molten steel for the backup roller into the solidified shell of the first part of the backup roller steel ingot, mixing the second part of the molten steel for the backup roller with the liquid molten steel in the solidified shell in step S2, and continuing to fill the ingot body and the ingot riser to obtain a complete backup roller steel ingot, including:

[0081] S41: Casting is performed in the vacuum chamber of step S21, the ingot mold remains the same, and the vacuum degree of the vacuum chamber is maintained at <0.5 Torr before casting;

[0082] S42: The second part of the molten steel refining ladle for the supporting rolls is hoisted by a 200t overhead crane, and the molten steel refining ladle for the supporting rolls is drained outside the refining ladle, and then the second part of the molten steel refining ladle for the supporting rolls is hoisted and placed on the vacuum cover of the vacuum chamber, and the vacuum is evacuated to a vacuum degree of 0.15 Torr;

[0083] S43: the refining ladle starts pouring, and argon gas is not blown into the refining ladle water port. When the second part of the support roll molten steel refining ladle pouring starts, the temperature of the molten steel in the refining ladle is measured, and the temperature is 1599°C. The molten steel enters the steel ingot mold in the vacuum chamber through the refining ladle water port;

[0084] S44: After the pouring is completed, the vacuum is destroyed. After the vacuum chamber returns to atmospheric pressure, 306 kg of heating agent and 153 kg of heat preservation agent are added to the molten steel surface in the ingot mold, and solidified for 36 hours to obtain a complete support roller ingot.

[0085] S5: The complete support roller steel ingot is demoulded, the nozzle is cut off, forging is performed, the riser is cut off, heat treatment is performed, and the support roller steel is machined.

[0086] Example 2

[0087] In this embodiment, a certain backup roller steel is produced, the weight of a complete backup roller steel ingot is 223 tons, and the weight of the ingot body (that is, the backup roller steel finally obtained) is about 183.75 tons.

[0088] The following steps are involved:

[0089] S1: Using two 100t electric furnaces, the raw materials of the support roller steel are smelted in sequence to obtain 100t and 84t of molten steel respectively;

[0090] The 100t molten steel provided by the first 100t electric furnace is added to the 160t refining furnace for deoxidation and desulfurization refining, and the alloy composition is adjusted to obtain the first portion of the first part of the support roll molten steel 106t, with a tapping temperature of 1577℃;

[0091] The first part of the first backup roll molten steel comprises, by mass percentage, C: 0.48%, Si: 0.39%, Mn: 0.57%, Cr: 4.92%, Ni: 0.41%, Mo: 0.98%, V: 0.35%, S: 0.002%, O: 0.0023%, and the balance is Fe;

[0092] The 84t molten steel provided by the second 100t electric furnace was added to the 130t refining furnace for deoxidation and desulfurization refining, and the alloy composition was adjusted to obtain the second first part of the support roll molten steel 88t, with a tapping temperature of 1583℃;

[0093] The composition of the second first part of the backup roll molten steel includes, by mass percentage, C: 0.52%, Si: 0.41%, Mn: 0.54%, Cr: 5.03%, Ni: 0.47%, Mo: 1.01%, V: 0.38%, S: 0.002%, O: 0.0020%, and the balance is Fe;

[0094] The weight of the two first parts of molten steel for the backup rolls accounts for 87.61% of the weight of the backup roll steel.

[0095] S2: The first part of the molten steel for the support roller is vacuum poured and solidified for 6.5 hours to obtain a solidified shell (thickness 500 mm) of the support roller ingot and liquid molten steel in the shell, including:

[0096] S21: Arrange the steel ingot mold in the 350t vacuum chamber, and keep the vacuum degree of the vacuum chamber less than 0.5 Torr before pouring;

[0097] S22: The ingot casting uses a 60t tundish equipped with an argon-blown stopper rod, and the first part of the support roll molten steel refining ladle is hoisted by two 350t overhead cranes;

[0098] First, the first portion of the first part of the molten steel for the supporting roller (106t) is drained outside the refining ladle, and then the 106t refining ladle is hoisted and placed above the tundish, and the 106t first portion of the molten steel for the supporting roller is poured into the tundish; the argon blowing plug rod of the tundish is lifted, argon gas is blown into the tundish, and the tundish begins to be poured. After the tundish has been poured for 4 minutes, the temperature of the molten steel in the tundish is measured, and the temperature is 1538°C. The molten steel and argon gas are mixed and enter the steel ingot mold in the vacuum chamber through the water inlet of the tundish;

[0099] Then the second portion of the first part of the supporting roller molten steel (88t) is drained outside the refining ladle, and then the 88t refining ladle is hoisted and placed above the tundish, and 88t of the second portion of the first part of the supporting roller molten steel is injected into the tundish; the argon blowing plug rod of the tundish is lifted, argon gas is blown into the tundish, and pouring of the tundish begins. After pouring the tundish for 5 minutes, the temperature of the molten steel in the tundish is measured, and the temperature is 1546℃. The molten steel and argon gas mixed enter the ingot mold in the vacuum chamber through the water inlet of the tundish.

[0100] S23: After the tundish pouring is completed, the vacuum is destroyed. After the vacuum chamber returns to atmospheric pressure, 194 kg of heat preservation agent is added and solidified for 6.5 hours to obtain a solidified shell (thickness 500 mm) of the support roller ingot and liquid steel in the shell.

[0101] S3: Using a 40t electric furnace, the raw materials of the support roller steel are smelted in sequence to obtain 30t of molten steel, and then the molten steel is added to a 40t refining furnace for deoxidation and desulfurization refining, and the alloy composition is adjusted to obtain 30t of the second part of molten steel for the support roller, with a tapping temperature of 1637°C;

[0102] The weight of the second part of the backup roller steel molten steel accounts for 12.39% of the weight of the backup roller steel, and its composition by mass percentage includes: C: 0.15%, Si: 0.30%, Mn: 0.41%, Cr: 0.53%, Ni: 0.46%, Mo: 1.01%, V: 0.06%, S: 0.002%, O: 0.0018%, and the balance is Fe;

[0103] S4: vacuum pouring the second part of the molten steel for the backup roller into the solidified shell of the first part of the backup roller steel ingot, mixing the second part of the molten steel for the backup roller with the liquid molten steel in the solidified shell in step S2, and continuing to fill the ingot body and the ingot riser to obtain a complete backup roller steel ingot, including:

[0104] S41: Casting is performed in the vacuum chamber of step S21, the ingot mold remains the same, and the vacuum degree of the vacuum chamber is maintained at <0.5 Torr before casting;

[0105] S42: The second part of the molten steel refining ladle for the supporting rolls is hoisted by a 200t overhead crane, and the molten steel refining ladle for the supporting rolls is drained outside the refining ladle, and then the second part of the molten steel refining ladle for the supporting rolls is hoisted and placed on the vacuum cover of the vacuum chamber, and the vacuum is evacuated to a vacuum degree of 0.15 Torr;

[0106] S43: the refining ladle begins pouring, and argon gas is not blown into the refining ladle water port. After the second part of the support roll molten steel refining ladle is poured for 1 minute, the temperature of the molten steel in the refining ladle is measured, and the temperature is 1608°C. The molten steel enters the steel ingot mold in the vacuum chamber through the refining ladle water port;

[0107] S44: After the pouring is completed, the vacuum is destroyed. After the vacuum chamber returns to atmospheric pressure, 224 kg of heat preservation agent and 448 kg of heat-generating agent are added to the molten steel surface in the ingot mold, and solidified for 42 hours to obtain a complete support roller ingot.

[0108] S5: The complete support roller steel ingot is demoulded, the nozzle is cut off, forging is performed, the riser is cut off, heat treatment is performed, and the support roller steel is machined.

[0109] Example 3

[0110] In this embodiment, a certain backup roller steel is produced. The weight of a complete backup roller steel ingot is 250 tons, and the weight of the ingot body (ie, the backup roller steel finally obtained) is about 207.92 tons.

[0111] The following steps are involved:

[0112] S1: Using two 100t electric furnaces, the raw materials of the support roller steel are smelted in sequence to obtain 115t and 94t of molten steel respectively;

[0113] The 115t molten steel provided by the first 100t electric furnace is added to the 160t refining furnace for deoxidation and desulfurization refining, and the alloy composition is adjusted to obtain the first portion of the first part of the support roll molten steel of 120t, with a tapping temperature of 1582℃;

[0114] The first part of the first backup roller steel has the following components by mass percentage: C: 0.50%, Si: 0.37%, Mn: 0.51%, Cr: 5.01%, Ni: 0.43%, Mo: 1.02%, V: 0.38%, S: 0.002%, O: 0.0025%, and the balance is Fe;

[0115] The 94t molten steel provided by the second 100t electric furnace is added to the 130t refining furnace for deoxidation and desulfurization refining, and the alloy composition is adjusted to obtain the second first part of the support roll molten steel 98t, with a tapping temperature of 1580℃;

[0116] The composition of the second first part of the backup roller steel molten steel includes, by mass percentage, C: 0.49%, Si: 0.40%, Mn: 0.55%, Cr: 5.05%, Ni: 0.44%, Mo: 0.99%, V: 0.40%, S: 0.002%, O: 0.0021%, and the balance is Fe;

[0117] The weight of the two first parts of molten steel for the backup rolls accounted for 87.2% of the weight of the backup roll steel.

[0118] S2: The first part of the molten steel for the support roller is vacuum poured and solidified for 7 hours to obtain a solidified shell (thickness 500 mm) of the support roller ingot and liquid molten steel in the shell, including:

[0119] S21: Arrange the steel ingot mold auxiliary tool in the 350t vacuum chamber, and keep the vacuum degree of the vacuum chamber less than 0.5 Torr before pouring;

[0120] S22: The ingot casting uses a 60t tundish equipped with an argon-blown stopper rod, and the first part of the support roll molten steel refining ladle is hoisted by two 350t overhead cranes;

[0121] First, the first portion of the first part of the molten steel for the supporting roller (120t) is drained outside the refining ladle, and then the 120t refining ladle is hoisted and placed above the tundish, and the 120t first portion of the molten steel for the supporting roller is poured into the tundish; the argon blowing plug of the tundish is lifted, argon gas is blown in, and the tundish begins to pour. After the tundish has been poured for 4 minutes, the temperature of the molten steel in the tundish is measured, and the temperature is 1541℃. The molten steel and argon gas are mixed and enter the steel ingot mold in the vacuum chamber through the water inlet of the tundish;

[0122] Then the second portion of the first part of the supporting roller molten steel (98t) is drained outside the refining ladle, the 98t refining ladle is hoisted and placed above the tundish, and 98t of the second portion of the first part of the supporting roller molten steel is injected into the tundish; the argon blowing plug rod of the tundish is lifted, argon gas is blown in, and the tundish begins to be poured. After the tundish has been poured for 4 minutes, the temperature of the molten steel in the tundish is measured, and the temperature is 1544℃. The molten steel and argon gas mixed enter the ingot mold in the vacuum chamber through the water inlet of the tundish.

[0123] S23: After the tundish pouring is completed, the vacuum is destroyed. After the vacuum chamber returns to atmospheric pressure, 218 kg of heat preservation agent is added and solidified for 7 hours to obtain a solidified shell (thickness 500 mm) of the support roller ingot and liquid steel in the shell.

[0124] S3: Using a 40t electric furnace, the raw materials of the support roller steel are smelted in sequence to obtain 32t of molten steel, and then the molten steel is added to a 40t refining furnace for deoxidation and desulfurization refining, and the alloy composition is adjusted to obtain 32t of the second part of the support roller molten steel, with a tapping temperature of 1635°C;

[0125] The weight of the second part of the backup roller steel molten steel accounts for 12.8% of the weight of the backup roller steel, and its composition by mass percentage includes: C: 0.16%, Si: 0.30%, Mn: 0.43%, Cr: 0.68%, Ni: 0.50%, Mo: 1.05%, V: 0.08%, S: 0.002%, O: 0.0021%, and the balance is Fe;

[0126] S4: vacuum pouring the second part of the molten steel for the backup roller into the solidified shell of the first part of the backup roller steel ingot, mixing the second part of the molten steel for the backup roller with the liquid molten steel in the solidified shell in step S2, and continuing to fill the ingot body and the ingot riser to obtain a complete backup roller steel ingot, including:

[0127] S41: Casting is performed in the vacuum chamber of step S21, the ingot mold remains the same, and the vacuum degree of the vacuum chamber is maintained at <0.5 Torr before casting;

[0128] S42: The second part of the molten steel refining ladle for the supporting rolls is hoisted by a 250t overhead crane, and the molten steel refining ladle for the supporting rolls is drained outside the refining ladle. Then, the second part of the molten steel refining ladle for the supporting rolls is hoisted and placed on the vacuum cover of the vacuum chamber, and the vacuum is evacuated to a vacuum degree of 0.15 Torr.

[0129] S43: the refining ladle begins to pour, and argon is not blown into the refining ladle water port. After the second part of the support roll molten steel refining ladle is poured for 2 minutes, the temperature of the molten steel in the refining ladle is measured, and the temperature is 1610°C. The molten steel enters the steel ingot mold in the vacuum chamber through the refining ladle water port;

[0130] S44: After the pouring is completed, the vacuum is destroyed. After the vacuum chamber returns to atmospheric pressure, 250 kg of heat preservation agent and 500 kg of heat-generating agent are added to the molten steel surface in the ingot mold, and solidified for 45 hours to obtain a complete support roller steel ingot.

[0131] S5: The complete support roller steel ingot is demoulded, the nozzle is cut off, forging is performed, the riser is cut off, heat treatment is performed, and the support roller steel is machined.

[0132] Comparative Example 1

[0133] In this comparative example, a certain backup roller steel is produced, and the weight of the finally obtained backup roller steel (i.e., the backup roller steel ingot body) is the same as that in Example 1, and the weight of the complete backup roller steel ingot is 165t.

[0134] The following steps are involved:

[0135] S1: The raw materials of the support roller steel are smelted in a 100t electric furnace and a 40t electric furnace in turn to obtain 156t of molten steel, which is then added to a 160t refining furnace for deoxidation and desulfurization refining, and the alloy composition is adjusted to obtain 165t of molten steel for support rollers, with a tapping temperature of 1580°C;

[0136] The weight of the support roller molten steel accounts for 100% of the weight of the support roller ingot, and its components, by mass percentage, include: C: 0.50%, Si: 0.40%, Mn: 0.49%, Cr: 4.92%, Ni: 0.43%, Mo: 1.10%, V: 0.45%, S: 0.002%, O: 0.0021%, and the balance is Fe;

[0137] S2: vacuum pouring the molten steel for the support roller and solidifying it for 39 hours to obtain a complete support roller ingot, including:

[0138] S21: Arrange the steel ingot mold in the 350t vacuum chamber, and keep the vacuum degree of the vacuum chamber less than 0.5 Torr before pouring;

[0139] S22: A 60t tundish is used for ingot casting and equipped with an argon-blowing stopper rod. The support roller molten steel refining ladle is hoisted by a 350t overhead crane to drain the refining ladle. The support roller molten steel refining ladle is then hoisted and placed above the tundish. The support roller molten steel is poured into the tundish.

[0140] S23: lift the tundish argon blowing plug rod, blow argon into the tundish, and start pouring. After the first support roller molten steel tundish is poured for 4 minutes, the temperature of the molten steel in the tundish is measured, and the temperature is 1547℃. The molten steel and argon gas mix and enter the steel ingot mold in the vacuum chamber through the tundish water inlet;

[0141] S24: After the tundish pouring is completed, the vacuum is destroyed. After the vacuum chamber returns to atmospheric pressure, 330 kg of heating agent and 165 kg of heat preservation agent are added and solidified for 39 hours to obtain a complete support roller ingot.

[0142] S3: The complete support roller steel ingot is demoulded, the nozzle is cut off, forging is performed, the riser is cut off, heat treatment is performed, and the support roller steel is machined.

[0143] Comparative Example 2

[0144] In this comparative example, a certain backup roller steel is produced, and the weight of the finally obtained backup roller steel (i.e., the backup roller steel ingot body) is the same as that of Example 2, and the weight of the complete backup roller steel ingot is 242t.

[0145] The following steps are involved:

[0146] S1: Using two 100t electric furnaces, the raw materials of the support roller steel are smelted in sequence to obtain 100t and 95t of molten steel respectively;

[0147] The 100t molten steel provided by the first 100t electric furnace is added to the 160t refining furnace for deoxidation and desulfurization refining, and the alloy composition is adjusted to obtain the first portion of the first part of the support roll molten steel 106t, with a tapping temperature of 1583℃;

[0148] The first batch of molten steel for backup rollers has the following components by mass percentage: C: 0.51%, Si: 0.38%, Mn: 0.55%, Cr: 5.03%, Ni: 0.40%, Mo: 1.03%, V: 0.40%, S: 0.002%, O: 0.0019%, and the balance is Fe;

[0149] The 95t molten steel provided by the second 100t electric furnace is added to the 130t refining furnace for deoxidation and desulfurization refining, and the alloy composition is adjusted to obtain the second first part of the support roll molten steel of 100t, with a tapping temperature of 1578℃;

[0150] The second portion of the backup roll steel molten steel has the following components by mass percentage: C: 0.52%, Si: 0.39%, Mn: 0.51%, Cr: 5.13%, Ni: 0.49%, Mo: 1.05%, V: 0.36%, S: 0.002%, O: 0.0021%, and the balance is Fe;

[0151] The weight of the two first parts of molten steel for the backup rolls accounts for 85.12% of the weight of the backup roll steel.

[0152] S2: Using a 40t electric furnace, the raw materials of the support roller steel are smelted in sequence to obtain 30t of molten steel, which is then added to a 40t refining furnace for deoxidation and desulfurization refining, and the alloy composition is adjusted to obtain 36t of the second part of the support roller molten steel, with a tapping temperature of 1635°C;

[0153] The weight of the second part of the backup roller steel molten steel accounts for 14.87% of the weight of the backup roller steel, and its composition by mass percentage includes: C: 0.15%, Si: 0.35%, Mn: 0.42%, Cr: 0.53%, Ni: 0.46%, Mo: 1.01%, V: 0.16%, S: 0.002%, O: 0.0018%, and the balance is Fe;

[0154] S3: vacuum pouring the first and second portions of molten steel for the support roll, including:

[0155] S31: Arrange the steel ingot mold auxiliary tool in the 350t vacuum chamber, and keep the vacuum degree of the vacuum chamber less than 0.5 Torr before pouring;

[0156] S32: The ingot casting uses a 60t tundish equipped with an argon-blown stopper rod, and the first part of the support roll molten steel refining ladle is hoisted by two 350t overhead cranes;

[0157] First, the first portion of the first part of the molten steel for supporting rollers (106t) is drained outside the refining ladle, and then the 106t refining ladle is hoisted and placed above the tundish, and the 106t first portion of the molten steel for supporting rollers is poured into the tundish; the argon blowing plug rod of the tundish is lifted, argon gas is blown into the tundish, and pouring of the tundish begins. After pouring the tundish for 4 minutes, the temperature of the molten steel in the tundish is measured, and the temperature is 1543°C. The molten steel and argon gas are mixed and enter the steel ingot mold in the vacuum chamber through the water inlet of the tundish;

[0158] Then the second portion of the first part of the molten steel for supporting rollers (95t) is drained outside the refining ladle, and then the 95t refining ladle is hoisted and placed above the tundish, and the 95t second portion of the first part of the molten steel for supporting rollers is poured into the tundish; the argon blowing plug rod of the tundish is lifted, argon gas is blown in, and the tundish begins to be poured. After the tundish has been poured for 4 minutes, the temperature of the molten steel in the tundish is measured, and the temperature is 1541°C. The molten steel and argon gas are mixed and enter the steel ingot mold in the vacuum chamber through the water inlet of the tundish;

[0159] Then the second part of the molten steel refining ladle for supporting rollers is hoisted by a 200t overhead crane, and the outside of the refining ladle is drained. Then the second part of the molten steel refining ladle for supporting rollers is hoisted and placed on the vacuum cover of the vacuum chamber, and the vacuum is evacuated to a vacuum degree of 0.15 Torr. The refining ladle begins to be poured, and argon is not blown into the water inlet of the refining ladle. After the second part of the molten steel refining ladle for supporting rollers has been poured for 1 minute, the temperature of the molten steel in the refining ladle is measured, and the temperature is 1605℃. The molten steel enters the steel ingot mold in the vacuum chamber through the water inlet of the refining ladle.

[0160] S4: After the pouring is completed, the vacuum is destroyed. After the vacuum chamber returns to atmospheric pressure, 242 kg of heat preservation agent and 484 kg of heat-generating agent are added to the molten steel surface in the ingot mold, and solidified for 42 hours to obtain a complete support roller ingot.

[0161] S5: The complete support roller steel ingot is demoulded, the nozzle is cut off, forging is performed, the riser is cut off, heat treatment is performed, and the support roller steel is machined.

[0162] Comparative Example 3

[0163] In this comparative example, a certain backup roller steel is produced, and the weight of the backup roller steel (i.e., the backup roller steel ingot body) finally obtained is the same as that of Example 3, and the weight of the complete backup roller steel ingot is 270t.

[0164] The following steps are involved:

[0165] S1: Using two 100t electric furnaces, the raw materials of the support roller steel are smelted in sequence to obtain 115t and 110t of molten steel respectively;

[0166] The 115t molten steel provided by the first 100t electric furnace is added to the 160t refining furnace for deoxidation and desulfurization refining, and the alloy composition is adjusted to obtain the first portion of the first part of the support roll molten steel of 120t, with a tapping temperature of 1582℃;

[0167] The first part of the first backup roller steel has the following components by mass percentage: C: 0.49%, Si: 0.35%, Mn: 0.52%, Cr: 4.98%, Ni: 0.42%, Mo: 0.96%, V: 0.39%, S: 0.002%, O: 0.0022%, and the balance is Fe;

[0168] The 110t molten steel provided by the second 100t electric furnace is added to the 160t refining furnace for deoxidation and desulfurization refining, and the alloy composition is adjusted to obtain the second first part of the support roll molten steel 115t, with a tapping temperature of 1582℃;

[0169] The composition of the second first part of the backup roller steel molten steel includes, by mass percentage, C: 0.50%, Si: 0.42%, Mn: 0.53%, Cr: 5.09%, Ni: 0.50%, Mo: 1.00%, V: 0.37%, S: 0.002%, O: 0.0017%, and the balance is Fe;

[0170] The weight of the two first parts of molten steel for the backup rolls accounts for 87.03% of the weight of the backup roll steel.

[0171] S2: The first part of the molten steel for the support roller is vacuum poured and solidified for 7 hours to obtain a solidified shell (thickness 500 mm) of the support roller ingot and liquid molten steel in the shell, including:

[0172] S21: Arrange the steel ingot mold auxiliary tool in the 350t vacuum chamber, and keep the vacuum degree of the vacuum chamber less than 0.5 Torr before pouring;

[0173] S22: The ingot casting uses a 60t tundish equipped with an argon-blown stopper rod, and the first part of the support roll molten steel refining ladle is hoisted by two 350t overhead cranes;

[0174] First, the first portion of the first part of the molten steel for the supporting roller (120t) is drained outside the refining ladle, and then the 120t refining ladle is hoisted and placed above the tundish, and the 120t first portion of the molten steel for the supporting roller is poured into the tundish; the argon blowing plug rod of the tundish is lifted, argon gas is blown into the tundish, and the tundish begins to be poured. After the tundish has been poured for 4 minutes, the temperature of the molten steel in the tundish is measured, and the temperature is 1540℃. The molten steel and argon gas are mixed and enter the steel ingot mold in the vacuum chamber through the tundish water inlet;

[0175] Then the second portion of the first part of the supporting roller molten steel (115t) is drained outside the refining ladle, the 115t refining ladle is hoisted and placed above the tundish, and the 115t second portion of the first part of the supporting roller molten steel is poured into the tundish; the argon blowing plug rod of the tundish is lifted, argon gas is blown in, and the tundish begins to be poured. After the tundish has been poured for 4 minutes, the temperature of the molten steel in the tundish is measured, and the temperature is 1543℃. The molten steel and argon gas mixed enter the ingot mold in the vacuum chamber through the water inlet of the tundish.

[0176] S23: After the tundish pouring is completed, the vacuum is destroyed. After the vacuum chamber returns to atmospheric pressure, 235 kg of heat preservation agent is added and solidified for 7 hours to obtain a solidified shell (thickness 500 mm) of the support roller ingot and liquid steel in the shell.

[0177] S3: Using a 40t electric furnace, the raw materials of the support roller steel are smelted in sequence to obtain 32t of molten steel, which is then added to a 40t refining furnace for deoxidation and desulfurization refining, and the alloy composition is adjusted to obtain 35t of the second part of the support roller molten steel, with a tapping temperature of 1638°C;

[0178] The weight of the second part of the backup roller steel molten steel accounts for 12.96% of the weight of the backup roller steel, and its composition by mass percentage includes: C: 0.46%, Si: 0.40%, Mn: 0.63%, Cr: 5.18%, Ni: 0.45%, Mo: 1.00%, V: 0.36%, S: 0.002%, O: 0.0020%, and the balance is Fe;

[0179] S4: vacuum pouring the second part of the molten steel for the backup roller into the solidified shell of the first part of the backup roller steel ingot, mixing the second part of the molten steel for the backup roller with the liquid molten steel in the solidified shell in step S2, and continuing to fill the ingot body and the ingot riser to obtain a complete backup roller steel ingot, including:

[0180] S41: Casting is performed in the vacuum chamber of step S21, the ingot mold remains the same, and the vacuum degree of the vacuum chamber is maintained at <0.5 Torr before casting;

[0181] S42: The second part of the molten steel refining ladle for the supporting rolls is hoisted by a 250t overhead crane, and the molten steel refining ladle for the supporting rolls is drained outside the refining ladle. Then, the second part of the molten steel refining ladle for the supporting rolls is hoisted and placed on the vacuum cover of the vacuum chamber, and the vacuum is evacuated to a vacuum degree of 0.15 Torr.

[0182] S43: The refining ladle begins to pour, and argon gas is not blown into the refining ladle water port. After the second part of the support roll molten steel refining ladle is poured for 1 minute, the temperature of the molten steel in the refining ladle is measured, and the temperature is 1606°C. The molten steel enters the steel ingot mold in the vacuum chamber through the refining ladle water port;

[0183] S44: After the pouring is completed, the vacuum is destroyed. After the vacuum chamber returns to atmospheric pressure, 270 kg of heat preservation agent and 540 kg of heat-generating agent are added to the molten steel surface in the ingot mold, and solidified for 45 hours to obtain a complete support roller steel ingot.

[0184] S5: The complete support roller steel ingot is demoulded, the nozzle is cut off, forging is performed, the riser is cut off, heat treatment is performed, and the support roller steel is machined.

[0185] Table 1 shows the parameter characterization of the steel ingots of the embodiments of the present invention and the comparative examples; Figure 1 It is a schematic diagram of the implementation process of the method of the present invention; Figure 2 Schematic diagram of shrinkage and shrinkage cavity of the support roller steel ingot of Example 1 of the present invention; Figure 3 The diagram is a schematic diagram of the shrinkage and shrinkage cavity of the support roller steel ingot of comparative example 1 of the present invention. As can be seen from Table 1, when using the same mold to produce support roller steel with the same ingot weight, the riser ratio of the method of the present invention can be reduced from 20% to 21% to 14% to 15%, and the ingot ratio can be increased from 76% to 78% to 81% to 83%, and the alloy dosage and production cost required to produce support roller steel of the same specification are less than those of the comparative example, and the hardness of the support roller steel is equivalent to that of the comparative example. Figure 2 and Figure 3 It can be seen that the shrinkage cavity and looseness of the center of the support roller steel ingot in the embodiment of the present invention are significantly improved compared with the control example.

[0186] Table 1 Parameters of steel ingots of the present invention and comparative examples

[0187]

[0188] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for producing backup roller steel, characterized in that: The following steps are involved: S1: smelting, deoxidation, desulfurization and refining of the raw materials of the support roller steel ingot, adjusting the alloy composition in sequence, obtaining the first part of the support roller molten steel, and tapping the steel; S2: vacuum pouring and solidifying the first portion of the molten steel for the support roller to obtain a solidified shell of the first portion of the support roller steel ingot and liquid molten steel in the solidified shell; S3: smelting, deoxidation and desulfurization refining, and adjusting the alloy composition of the raw materials of the support roller steel ingot in sequence to obtain the second part of the support roller molten steel, and tapping the steel; S4: vacuum pouring the second part of the molten steel for the backup roller into the solidified shell of the first part of the backup roller steel ingot, mixing the second part of the molten steel for the backup roller with the liquid molten steel in the solidified shell in step S2, and continuing to fill the ingot body and the ingot riser, solidifying, and obtaining a complete backup roller steel ingot; S5: demoulding the complete support roller steel ingot, cutting off the nozzle, forging, cutting off the riser, heat treatment, and machining to obtain the support roller steel; There is a difference between the composition of the molten steel of the first backup roll and the composition of the molten steel of the second backup roll.

2. The production method according to claim 1, characterized in that The step S2 comprises: S21: Arrange the steel ingot mold in a 150-350t vacuum chamber, and keep the vacuum degree of the vacuum chamber ≤ 0.5 Torr before pouring; S22: The ingot casting uses a 60-100t tundish equipped with an argon-blown stopper rod. The first part of the support roll molten steel refining ladle is hoisted by a 200-350t overhead crane to drain the refining ladle. Then the first part of the support roll molten steel refining ladle is hoisted and placed above the tundish. The first part of the support roll molten steel is poured into the tundish. S23: lift the argon blowing plug rod of the tundish, blow argon into it, and start pouring the tundish. After the first part of the molten steel of the support roller is poured in the tundish for 3 to 5 minutes, measure the temperature of the molten steel in the tundish to ensure that the temperature of the molten steel in the tundish is controlled at 1530℃~1550℃. The molten steel and argon gas are mixed and enter the ingot mold in the vacuum chamber through the tundish water inlet; S24: After the tundish pouring is completed, the vacuum is destroyed, and after the vacuum chamber returns to atmospheric pressure, 0.8-1.2 kg / t of heat preservation agent is added for solidification to obtain a solidified shell of the support roller ingot and liquid steel in the solidified shell.

3. The production method according to claim 2, characterized in that: The step S4 comprises: S41: Casting is performed in the vacuum chamber of step S21, the ingot mold remains the same, and the vacuum degree of the vacuum chamber is maintained at ≤0.5 Torr before casting; S42: The second part of the molten steel refining ladle for the supporting roller is hoisted by a 200-350t overhead crane, and the molten steel refining ladle for the supporting roller is drained outside the refining ladle, and then the second part of the molten steel refining ladle for the supporting roller is hoisted and placed on the vacuum cover of the vacuum chamber, and the vacuum is evacuated to a vacuum degree of ≤0.5 Torr; S43: The refining ladle begins pouring, and argon is not blown into the refining ladle water port. The second part of the support roller molten steel refining ladle is poured within 0 to 3 minutes. The temperature of the molten steel in the refining ladle is measured to ensure that the temperature of the molten steel in the refining ladle is controlled at 1590 to 1610°C. The molten steel enters the ingot mold in the vacuum chamber through the refining ladle water port; S44: After the pouring is completed, the vacuum is destroyed. After the vacuum chamber returns to atmospheric pressure, 1.8-2.2 kg / t of exothermic agent and 0.8-1.2 kg / t of heat-insulating agent are added to the molten steel surface in the ingot mold, and solidified to obtain a complete support roller ingot.

4. The production method according to claim 1, characterized in that The composition of the molten steel of the first part of the supporting roller includes, by mass percentage, C: 0.45%~0.55%, Si: 0.20%~0.70%, Mn: 0.40%~0.70%, Cr: 4.50%~5.50%, Ni: 0.40%~0.50%, Mo: 0.90%~1.10%, V: 0.35%~0.45%, S≤0.002%, O≤0.0025%, and the balance is Fe.

5. The production method according to claim 4, characterized in that: The components of the molten steel of the second part of the supporting roller include, by mass percentage, C: 0.15%~0.25%, Si: 0.20%~0.70%, Mn: 0.20%~0.70%, Cr: 0.50%~1.50%, Ni: 0.20%~0.50%, Mo: 0.10%~1.10%, V: 0.05%~0.45%, S≤0.002%, O≤0.0025%, and the balance is Fe.

6. The production method according to claim 1, characterized in that: The weight of the first part of the molten steel for the backup roller accounts for 87% to 89% of the weight of the backup roller steel ingot, and the weight of the second part of the molten steel for the backup roller accounts for 11% to 13% of the weight of the backup roller steel ingot.

7. The production method according to claim 1, characterized in that: In the step S1, the tapping temperature is 1570-1590°C.

8. The production method according to claim 1, characterized in that: In the step S2, the coagulation time is 4 to 8 hours.

9. The production method according to claim 1, characterized in that: In step S3, the tapping temperature is 1620-1640°C.

10. The production method according to claim 1, characterized in that: In the step S4, the coagulation time is 36 to 45 hours.

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