CN112792304B - Preparation method of large chromium alloy strip steel supporting roller - Google Patents

Preparation method of large chromium alloy strip steel supporting roller Download PDF

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Publication number
CN112792304B
CN112792304B CN202011432106.0A CN202011432106A CN112792304B CN 112792304 B CN112792304 B CN 112792304B CN 202011432106 A CN202011432106 A CN 202011432106A CN 112792304 B CN112792304 B CN 112792304B
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roller
temperature
steel
furnace
heating
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CN112792304A (en
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孙建勋
蒋志芳
董国卿
陈兴
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Xingtai Delong Machinery & Mill Roll Co ltd
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Xingtai Delong Machinery & Mill Roll Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/22—Moulds for peculiarly-shaped castings
    • B22C9/28—Moulds for peculiarly-shaped castings for wheels, rolls, or rollers
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/52—Manufacture of steel in electric furnaces
    • C21C5/54—Processes yielding slags of special composition
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0006—Adding metallic additives
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/06—Deoxidising, e.g. killing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/064—Dephosphorising; Desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C21D1/28—Normalising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C21D1/32—Soft annealing, e.g. spheroidising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/38—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for roll bodies
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

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Abstract

The invention provides a preparation method of a large chromium alloy strip steel supporting roll, which comprises the following alloy components in percentage by mass: 0.45-0.65% of C, 0.60-0.80% of Si, 0.60-0.80% of Mn, less than or equal to 0.02% of P, less than or equal to 0.02% of S, 4.00-6.00% of Cr, 0.50-0.60% of Ni, 0.50-0.80% of Mo, 0.20-0.40% of V, 0.10-0.30% of Nb, more than or equal to 0.03% of Re, and the balance of Fe and unavoidable impurities; the preparation method comprises the steps of smelting primary molten steel in an arc furnace, slagging, removing slag, discharging from the furnace, refining in an LF furnace, tapping and pouring to obtain a semi-finished product of the support roller, and sequentially carrying out diffusion annealing, spheroidizing, normalizing and tempering after hot unpacking to obtain the finished product of the support roller. The preparation method of the large chromium alloy strip steel supporting roller adopts a casting mode to prepare the supporting roller, uses casting instead of forging, and can improve the shape and distribution of carbide through a special heat treatment process, refine crystal grains of a crystal structure, improve the wear resistance of the supporting roller, and enhance the tensile strength, impact extrusion toughness and heat crack resistance of the supporting roller, thereby improving the comprehensive performance of the supporting roller.

Description

Preparation method of large chromium alloy strip steel supporting roller
Technical Field
The invention relates to the technical field of roller preparation, in particular to a preparation method of a large chromium alloy strip steel supporting roller.
Background
Backup rolls are important components in rolling mills to support the work rolls or intermediate rolls in order to prevent the work rolls from flexing and affecting the yield and quality of the slab, strip. Therefore, the supporting roller firstly has better abrasion rigidity, and secondly, the supporting roller forms a complex contact line with the working roller during rolling operation, has higher yield strength after long-term contact rolling, and has excellent friction toughness and anti-cracking performance. Therefore, the excellent wear resistance, the good friction toughness and the stronger anti-fatigue and anti-heat-cracking performance of the roller body are the necessary conditions of the supporting roller.
With the development of high speed, large size and high precision of cold and hot rolling mills, the requirements for supporting rolls are continuously increasing. The modern back-up rolls of the cold and hot tandem rolling mill are usually forged steel back-up rolls, especially for large-scale rolls with the roll body diameter of more than 1.1m, the technology requirements are high, the process is complex, the manufacturing difficulty is high, the production procedures are multiple, the period is long, and the heat treatment is usually carried out in special equipment, so that the productivity is restricted.
For example, the backup rolls used in the domestic hot finishing mill groups at present are mostly made of DG-Cr2-DGCr5 forged steel and high alloy steel, the former is cast to forge, the yield is low, the production period is long, the energy consumption is high, the latter is made of more noble alloy, the consumption of resources is large, the backup rolls made of the materials are influenced by the rolling environment, the backup rolls are often subjected to alternating bending stress in the complex contact line with the working rolls, and the working surface of the backup rolls can be subjected to friction indentation when the rolled piece passes due to the interweaving influence of the heat conduction extrusion impact force of the high-temperature strip steel rolled piece, so that the polishing amount of the rolls is increased. And as the operation time is prolonged, the compression stress of the bearing roller surface and the tensile stress of the core part are interacted, so that the internal stress energy is continuously increased to generate thermal cracks, and finally, the shoulder stripping and peeling of the two sides of the roller surface are caused, thereby affecting the performance of the supporting roller.
Disclosure of Invention
In view of the above, the present invention aims to provide a method for manufacturing a large chromium alloy strip steel supporting roll, so as to improve the performance of the supporting roll.
In order to achieve the above purpose, the technical scheme of the invention is realized as follows:
a preparation method of a large chromium alloy strip steel supporting roller comprises the following alloy components in percentage by mass: 0.45-0.65% of C, 0.60-0.80% of Si, 0.60-0.80% of Mn, less than or equal to 0.02% of P, less than or equal to 0.02% of S, 4.00-6.00% of Cr, 0.50-0.60% of Ni, 0.50-0.80% of Mo, 0.20-0.40% of V, 0.10-0.30% of Nb, more than or equal to 0.03% of Re, and the balance of Fe and unavoidable impurities; and the preparation method comprises the following steps:
s1, smelting primary molten steel in an electric arc furnace, and slagging when the steel temperature is 1510-1530 ℃;
s2, when the slag is white, cleaning the slag out, and transferring the slag into an LF furnace for refining;
s3, in the refining process, measuring the temperature, feeding an aluminum cake, sampling and analyzing, and performing rough adjustment;
s4, adding silicon carbide in batches for foam slagging, heating to 1560-1580 ℃ when the slag is white and the alkalinity is more than or equal to 2.5, maintaining the reducing atmosphere in the furnace, sampling and analyzing molten steel again after white slag is maintained for 20-25min, fine tuning according to the process requirement, preparing steel after the molten steel components meet the design requirement, and covering the surface of the molten steel with carbonized rice hull covering agent after steel tapping;
s5, tapping and pouring, namely, sedating the molten steel for 8-15min, and then pouring to obtain a semi-finished product of the supporting roller;
s6, opening the semi-finished product of the support roller by adopting a hot box opening process, covering a heating and heat preserving area with a heat preserving agent after opening the box, and sequentially performing diffusion annealing, spheroidizing, normalizing and tempering to obtain the finished product of the support roller;
wherein the diffusion annealing comprises the steps of heating the roller temperature from 450 ℃ for the first time, keeping the temperature for 12 hours when the roller temperature is up to 800 ℃, then heating the roller temperature for the second time, keeping the temperature for 24-36 hours when the roller temperature reaches 1050-1080 ℃, and then air-cooling;
the spheroidizing treatment comprises the steps of feeding a roller Wen Kongleng to 450-500 ℃ into a furnace for heating, keeping the roller temperature to 680-800 ℃, preserving heat for 20-30 hours, cooling the furnace to 500 ℃, discharging the furnace, cooling the furnace to normal temperature, and then performing rough machining, and finishing the process flaw detection;
normalizing the rough machined roller, heating the roller to 660-680 ℃, preserving heat for 6-8h, heating the roller to 960-980 ℃, preserving heat for 32-36h, and performing water mist spray quenching;
the tempering comprises the steps of feeding the steel into a furnace at the temperature of 400-420 ℃ for 6 hours, heating, preserving heat for 25-30 hours when the temperature of the steel is 540-560 ℃, cooling the steel to the normal temperature, and discharging the steel from the furnace for finish machining.
Further, the components of the slag former during slag formation in the step S1 comprise the following components in percentage by mass: fluorite: 2-3%, iron ore: 40-50%, calcium oxide: 15-20% of calcium carbide: 10-15% of lime and the balance of lime.
Further, the particle size of the iron ore is between 30 and 50mm, the lime is in a block shape, and the particle size is between 30 and 50 mm.
Further, argon is blown in the whole process in the refining process of the molten steel in the step s3, the flow rate of the argon is 3-4m < 3 >/min, and the pressure is 0.15-0.20MPa.
Further, in the step S4, silicon carbide is added in 2 times, and 5-8 Kg/ton of steel is added each time.
Further, in the step S5, pouring is performed by adopting a top pouring process, the water gap is opened to 1/3 of running water when pouring is started, the water gap is fully opened when pouring to the roll body, the water gap is adjusted to 2/3 of running water when pouring to the roll neck of the upper roll, the water gap is adjusted to 1/3 of running water when pouring to the effective height of the roll neck of the upper roll, and meanwhile, the ladle is lifted to 500-800mm.
Further, in the casting process in the step S5, an electromagnetic vibrator is adopted to slightly vibrate a supporting roller die, and the vibration frequency is 60-120 times/min.
Further, in step S6, the box opening temperature is 560-650 ℃.
Further, the spheroidizing process is performed by heating to 680-800 ℃ at a speed of 20-30 ℃/h, the normalizing process is performed by heating to 660-680 ℃ at a speed of 20-30 ℃/h, heating to 960-980 ℃ at a speed of 30-40 ℃/h, and the tempering process is performed by heating to 540-560 ℃ at a speed of 14-16 ℃/h.
Compared with the prior art, the invention has the following advantages:
the preparation method of the large chromium alloy strip steel supporting roller adopts a casting mode to prepare the supporting roller, uses casting instead of forging, and can improve the form and distribution of carbide through an innovative casting method and a special heat treatment process, refine crystal grains of a crystal structure, improve the wear resistance of the supporting roller, and enhance the tensile strength, impact extrusion toughness and heat cracking resistance of the supporting roller, thereby improving the comprehensive performance of the supporting roller.
In addition, in the preparation method, related impurity elements can be effectively removed, molten steel is purified, and the adopted slag former component can effectively remove phosphorus and sulfur by feeding aluminum cakes in the refining process of an LF refining furnace and adding silicon carbide in batches. During pouring, through the adjustment of the steel ladle height, the pressure of the steel flowing to the riser under water can be adjusted, and the liquid level is oscillated, so that residues can float upwards, and a loose region of riser tissues can be reduced when the oscillation is utilized to promote molten steel to cool, solidify and crystallize. And in the pouring process, the density of the solidification and crystallization of molten steel can be enhanced by vibration, and the loosening and shrinkage cavity area of the whole casting is eliminated. Thus, the comprehensive performance of the prepared supporting roller is improved.
Detailed Description
It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.
The present invention will be described in detail with reference to examples.
The embodiment relates to a preparation method of a large-sized chromium alloy strip steel supporting roller, which comprises the following chemical components in percentage by mass as follows: 0.45-0.65% of C, 0.60-0.80% of Si, 0.60-0.80% of Mn, less than or equal to 0.02% of P, less than or equal to 0.02% of S, 4.00-6.00% of Cr, 0.50-0.60% of Ni, 0.50-0.80% of Mo, 0.20-0.40% of V, 0.10-0.30% of Nb, more than or equal to 0.03% of Re, and the balance of Fe and unavoidable impurities.
The preparation method of the large chromium alloy strip steel supporting roll comprises the steps of primary smelting molten steel in an arc furnace, slagging, slag removal, tapping, LF refining, sampling analysis, coarse blending and secondary slagging according to the technological requirements, sampling analysis for fine tuning, tapping and pouring after the molten steel components meet the design requirements to obtain a supporting roll semi-finished product, and then carrying out diffusion annealing, spheroidizing, normalizing and tempering in sequence after hot unpacking to obtain a supporting roll finished product.
In detail, in the molten steel smelting step, primary molten steel is smelted by adopting an electric arc furnace, slag is formed when the temperature of the steel is 1510-1530 ℃, wherein the components of the slag former in the slag forming process comprise the following components in percentage by mass: fluorite: 2-3%, iron ore: 40-50%, calcium oxide: 15-20% of calcium carbide: 10-15% of lime and the balance of lime. The iron ore is generally new ore with iron content of 20-40%, the particle size of the iron ore is 30-50mm, the lime is in a block shape, and the particle size is 30-50 mm. While the components of the slag former may preferably be 3% fluorite, 45% iron ore, 18% calcium oxide, 13% calcium carbide, and also preferably the iron ore has a particle size of 40mm and the lump lime has a particle size of 35mm.
In the slag-making step of molten steel smelting in an electric arc furnace, specifically, when the slag is white, the slag is scraped out and then transferred into an LF furnace for refining.
In the LF refining step, in the refining process, temperature measurement, aluminum cake feeding, sampling analysis and coarse adjustment are carried out. Argon is blown in the whole process, wherein the flow of the argon is 3-4m 3 The pressure per minute is 0.15-0.20MPa, preferably 0.18MPa. Then adding silicon carbide into 2 batches for foam slagging, adding 5-8 Kg/ton of steel each time, heating to 1560-1580 ℃ when the slag is white and the alkalinity is more than or equal to 2.5, maintaining the reducing atmosphere in the furnace, sampling and analyzing the molten steel again after the white slag is maintained for 20-25min, fine adjusting according to the process requirement, preparing steel after the steel temperature reaches the liquidus temperature +50-80 ℃, namely, the molten steel components meet the design requirement, covering the surface of the molten steel after the steel is tapped with carbonized rice hull covering agent, thereby playing a role of heat preservation on one hand, isolating oxygen in the air on the other hand, preventing the molten steel from contacting with the atmosphere to avoid the molten steelAnd (5) secondary oxidation. In addition, the aluminum cake fed in the refining process can deoxidize molten steel, and simultaneously, the contents of silicon, manganese and other alloy elements can reach the specification of finished steel.
In the tapping pouring step, firstly, after the steel ladle is lifted and calmed for 8-15min, pouring is started until the liquidus temperature is +30-50 ℃, so as to obtain a semi-finished product of the supporting roller through pouring. In the casting process, an electromagnetic vibrator is adopted to slightly vibrate a supporting roller die, a top casting technology is adopted, a water gap is opened to 1/3 of running water when casting is started, the water gap is fully opened when casting is performed to a roll body, the water gap is adjusted to 2/3 of running water when casting is performed to an upper roll neck, the water gap is adjusted to 1/3 of running water when casting is performed to the effective height of the upper roll neck, and meanwhile, a ladle is lifted to 500-800mm so as to increase the impact force of the steel underwater flow, the shrinkage effect of the upper area of the roll neck is enhanced by utilizing impact oscillation waves, and the loose tissue area of the upper roll neck can be eliminated. It should be noted that the vibration frequency of the electromagnetic vibrator is 60-120 times/min, and the vibration frequency of the electromagnetic vibrator can be adaptively adjusted in combination with the pouring rate of molten steel. A step of
In the case of hot unpacking, the semi-finished product of the supporting roller is unpacked at the unpacking temperature of 560-650 ℃ in the embodiment, and then the semi-finished product is put into a heat treatment furnace preheated to 500 ℃ for heat preservation for 4 hours while the semi-finished product is hot. And after diffusion annealing, spheroidizing, normalizing and tempering which are sequentially performed, wherein the diffusion annealing comprises the steps of heating the roller temperature from 450 ℃ for the first time, heating the roller temperature to 800 ℃ for 12 hours, heating the roller temperature for the second time, heating the roller temperature to 1050-1080 ℃ for 24-36 hours, and then air cooling the roller.
The spheroidizing treatment specifically comprises the steps of feeding a roller Wen Kongleng to 450-500 ℃ into a furnace for heating, heating at the speed of 20-30 ℃/h, heating the roller to 680-800 ℃, preserving heat for 20-30h, cooling the furnace to 500 ℃, discharging the furnace for air cooling to normal temperature, then roughly processing, and finishing the process flaw detection.
Normalizing specifically comprises heating up the roller for rough machining at 20-30deg.C/h, maintaining the temperature at 660-680 deg.C for 6-8h, heating up at 30-40deg.C/h, maintaining the temperature at 960-980 deg.C, and performing spray quenching with water mist after 32-36 h;
tempering specifically comprises the steps of feeding the steel into a furnace at the temperature of 400-420 ℃ for 6 hours, heating at the speed of 14-16 ℃/h, preserving heat for 25-30 hours when the temperature of the steel is 540-560 ℃, and discharging the steel from the furnace for finish machining after the steel is cooled to normal temperature.
According to the method for preparing the support roller, the support roller is prepared in a casting mode, forging is replaced by casting, the form and distribution of carbide can be improved through an innovative casting method and a special heat treatment process, crystal grains of a crystal structure are refined, the wear resistance of the support roller can be improved, the tensile strength, impact extrusion toughness and heat crack resistance of the support roller are enhanced, and therefore the comprehensive performance of the support roller can be improved.
In addition, in the preparation method, related impurity elements can be effectively removed, molten steel is purified, and the adopted slag former component can effectively remove phosphorus and sulfur by feeding aluminum cakes in the refining process of an LF refining furnace and adding silicon carbide in batches. During pouring, through the adjustment of the steel ladle height, the pressure of the steel flowing to the riser under water can be adjusted, and the liquid level is oscillated, so that residues can float upwards, and a loose region of riser tissues can be reduced when the oscillation is utilized to promote molten steel to cool, solidify and crystallize. And in the pouring process, the density of the solidification and crystallization of molten steel can be enhanced by vibration, and the loosening and shrinkage cavity area of the whole casting is eliminated. Thus, the comprehensive performance of the prepared supporting roller is improved.
The preparation of the backup roll of this embodiment will be further described below with specific preparation examples. Also in the following preparations, unless otherwise indicated, the process conditions referred to apply the preferred values described above.
Preparation example 1
In the preparation example, the alloy components of the supporting roller comprise the following components in percentage by mass: 0.55% of C, 0.70% of Si, 0.65% of Mn, 0.015% of P, 0.015% of S, 5.00% of Cr, 0.55% of Ni, 0.60% of Mo, 0.25% of V, 0.20% of Nb, 0.035% of Re, and the balance of Fe and unavoidable impurities.
And the preparation steps thereof include:
s1, smelting primary molten steel in an electric arc furnace, and slagging when the steel temperature reaches 1520 ℃;
s2, when the slag is white, cleaning the slag, and transferring the slag into an LF furnace for refining;
s3, in the refining process, measuring the temperature, feeding an aluminum cake, sampling and analyzing, and performing rough adjustment;
s4, adding silicon carbide in batches for foam slagging, heating to 1570 ℃ when the slag is white and the alkalinity is 2.7, maintaining the reducing atmosphere in the furnace, after white slag is maintained for 25min, sampling and analyzing molten steel again, fine adjusting according to the process requirement, preparing steel after the molten steel components meet the design requirement, and covering the surface of the molten steel with carbonized rice hull covering agent after steel tapping;
s5, tapping and pouring, namely, sedating the molten steel for 12 minutes, and then pouring to obtain a semi-finished product of the supporting roller;
s6, adopting a hot unpacking process to unpack the semi-finished support roller, covering a heating and heat-preserving area with a heat-preserving agent after unpacking, and sequentially carrying out diffusion annealing, spheroidizing, normalizing and tempering to obtain the finished support roller.
In the pouring of the step S5, the ladle is raised by 700mm, the frequency of the electromagnetic vibrator corresponds to the water gap flow speed of 1/3 running water, full opening, 2/3 running water and 1/3 running water, and the frequency is sequentially and correspondingly set to 120 times/min, 60 times/min, 100 times/min and 65 times/min. In step S6, the unpacking temperature is 600 ℃.
The diffusion annealing comprises the steps of first heating up the roller temperature from 450 ℃, preserving heat for 12 hours when the roller temperature is raised to 800 ℃, then carrying out second heating up, preserving heat for 31 hours when the roller temperature reaches 1060 ℃, and then carrying out air cooling. The spheroidizing treatment comprises the steps of feeding a roller Wen Kongleng to 470 ℃ to heat up, heating the roller to 720 ℃ at a speed of 28 ℃/h, preserving heat for 30 hours, cooling the roller to 500 ℃, discharging the roller to cool the roller to normal temperature, performing rough machining, and finishing the process flaw detection. The normalizing comprises normalizing and heating the rough machined roller to 670 ℃, preserving heat for 7 hours, heating at a speed of 25 ℃/h, heating the roller to 970 ℃, preserving heat for 34 hours, and then carrying out spray quenching.
The tempering comprises the steps of feeding the roller to 410 ℃ and keeping the temperature for 6 hours, heating up at a speed of 15 ℃/h, keeping the temperature for 28 hours when the roller temperature is 550 ℃, cooling the roller to normal temperature, and discharging and finishing.
Preparation example 2
In the preparation example, the alloy components of the supporting roller comprise the following components in percentage by mass: 0.45% of C, 0.60% of Si, 0.6% of Mn, 0.015% of P, 0.02% of S, 4.00% of Cr, 0.50% of Ni, 0.50% of Mo, 0.20% of V, 0.10% of Nb, 0.03% of Re, and the balance of Fe and unavoidable impurities.
And the preparation steps thereof include:
s1, smelting primary molten steel in an electric arc furnace, and slagging when the steel temperature is 1510 ℃;
s2, when the slag is white, cleaning the slag, and transferring the slag into an LF furnace for refining;
s3, in the refining process, measuring the temperature, feeding an aluminum cake, sampling and analyzing, and performing rough adjustment;
s4, adding silicon carbide in batches for foam slagging, heating to 1560 ℃ when the slag is white and the alkalinity is 2.5, maintaining the reducing atmosphere in the furnace, after white slag is maintained for 20min, sampling and analyzing molten steel again, fine-tuning according to the process requirements, preparing steel after the molten steel components meet the design requirements, and covering the surface of the molten steel with carbonized rice hull covering agent after steel tapping;
s5, tapping and pouring, namely, sedating molten steel for 9min, and then pouring to obtain a semi-finished product of the supporting roller;
s6, adopting a hot unpacking process to unpack the semi-finished support roller, covering a heating and heat-preserving area with a heat-preserving agent after unpacking, and sequentially carrying out diffusion annealing, spheroidizing, normalizing and tempering to obtain the finished support roller.
In the pouring of the step S5, the ladle is raised by 700mm, the frequency of the electromagnetic vibrator corresponds to the water gap flow speed of 1/3 running water, full opening, 2/3 running water and 1/3 running water, and the frequency is sequentially and correspondingly set to 120 times/min, 65 times/min, 100 times/min and 70 times/min. In step S6, the unpacking temperature is 560 ℃.
The diffusion annealing comprises the steps of first heating up the roller temperature from 450 ℃, preserving heat for 12 hours when the roller temperature is raised to 800 ℃, then carrying out second heating up, preserving heat for 36 hours when the roller temperature reaches 1050 ℃, and then carrying out air cooling. The spheroidizing treatment comprises the steps of feeding the roll Wen Kongleng to 470 ℃ into a furnace for heating, heating the roll to 665 ℃ at the speed of 20 ℃/h, preserving heat for 30 hours, cooling the furnace to 500 ℃, discharging the furnace, cooling the furnace to normal temperature, and then performing rough machining, and finishing the process flaw detection. The normalizing comprises normalizing and heating the rough machined roller to 660 ℃, preserving heat for 8 hours, heating at a speed of 30 ℃/h, heating to 965 ℃, preserving heat for 36 hours, and carrying out spray quenching.
The tempering comprises the steps of feeding the roller to 410 ℃ and keeping the temperature for 6 hours, heating up at the speed of 14 ℃/h, keeping the temperature for 30 hours when the roller temperature is 545 ℃, cooling the furnace to normal temperature, and discharging and finishing.
Preparation example 3
In the preparation example, the alloy components of the supporting roller comprise the following components in percentage by mass: 0.65% of C, 0.80% of Si, 0.8% of Mn, 0.02% of P and S:0.02%, 6.00% Cr, 0.60% Ni, 0.80% Mo, 0.40% V, 0.30% Nb, 0.03% Re, and the balance Fe and unavoidable impurities.
And the preparation steps thereof include:
s1, smelting primary molten steel in an electric arc furnace, and slagging when the steel temperature is 1530 ℃;
s2, when the slag is white, cleaning the slag, and transferring the slag into an LF furnace for refining;
s3, in the refining process, measuring the temperature, feeding an aluminum cake, sampling and analyzing, and performing rough adjustment;
s4, adding silicon carbide in batches for foam slagging, heating to 1580 ℃ when the slag is white and the alkalinity is 2.5, maintaining the reducing atmosphere in the furnace, after white slag is maintained for 20min, sampling and analyzing molten steel again, fine tuning according to the process requirement, preparing steel after the molten steel components meet the design requirement, and covering the surface of the molten steel with carbonized rice hull covering agent after steel tapping;
s5, tapping and pouring, namely, sedating the molten steel for 15min, and then pouring to obtain a semi-finished product of the supporting roller;
s6, adopting a hot unpacking process to unpack the semi-finished support roller, covering a heating and heat-preserving area with a heat-preserving agent after unpacking, and sequentially carrying out diffusion annealing, spheroidizing, normalizing and tempering to obtain the finished support roller.
In the pouring of the step S5, the ladle is raised by 700mm, the frequency of the electromagnetic vibrator corresponds to the water gap flow speed of 1/3 running water, full opening, 2/3 running water and 1/3 running water, and the frequency is sequentially and correspondingly set to 115 times/min, 65 times/min, 100 times/min and 70 times/min. In step S6, the unpacking temperature is 650 ℃.
The diffusion annealing comprises the steps of first heating up the roller temperature from 450 ℃, preserving heat for 12 hours when the roller temperature is raised to 800 ℃, then carrying out second heating up, preserving heat for 24 hours when the roller temperature reaches 1080 ℃, and then carrying out air cooling. The spheroidizing treatment comprises the steps of feeding a roller Wen Kongleng to 470 ℃ to heat up, heating the roller to 675 ℃ at a speed of 30 ℃/h, preserving heat for 20 hours, cooling the roller to 500 ℃, discharging the roller to cool the roller to normal temperature, performing rough machining, and finishing the process flaw detection. The normalizing comprises normalizing and heating the rough machined roller to 680 ℃, preserving heat for 6 hours, heating at a speed of 40 ℃/h, heating the roller to 980 ℃, preserving heat for 32 hours, and then carrying out spray quenching.
The tempering comprises the steps of feeding the roller to 420 ℃ and keeping the temperature for 6 hours, heating up at the speed of 16 ℃/h, keeping the temperature for 25 hours when the roller temperature is 560 ℃, cooling the furnace to normal temperature, and discharging and finishing.
The hardness of the supporting rolls prepared in the three preparation examples is detected respectively, the hardness of the roll surface of the prepared supporting rolls is 70-75HSD, the hardness of the roll neck is 40-48HSD, and meanwhile, the tensile strength of the supporting rolls prepared in each preparation example is detected, and the tensile strength of each prepared supporting roll is more than or equal to 920Mpa. Further, by observing the metallographic structure of each support roller prepared, it was found that the metallographic structure was of a fine-grained metal carbide+tempered sorbite+tempered bainite+a small amount of martensite.
As can be seen from the above preparation examples, the prepared support roller has better roller surface hardness and roller neck hardness, higher tensile strength and better metallographic structure morphology by adopting the preparation method of the embodiment. Therefore, the supporting roller prepared by the method has better comprehensive performance, and the millimeter manufacturing amount of the supporting roller prepared by the method is improved by more than 3 times compared with that of the traditional supporting roller when hot rolling strip steel is carried out, so that better economic benefit and social benefit can be obtained.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.

Claims (4)

1. A preparation method of a large chromium alloy strip steel supporting roller is characterized by comprising the following steps: the large chromium alloy strip steel supporting roller comprises the following alloy components in percentage by mass: 0.45-0.65% of C, 0.60-0.80% of Si, 0.60-0.80% of Mn, less than or equal to 0.02% of P, less than or equal to 0.02% of S, 4.00-6.00% of Cr, 0.50-0.60% of Ni, 0.50-0.80% of Mo, 0.20-0.40% of V, 0.10-0.30% of Nb, more than or equal to 0.03% of Re, and the balance of Fe and unavoidable impurities; and the preparation method comprises the following steps:
s1, smelting primary molten steel by an electric arc furnace, slagging when the steel temperature is 1510-1530 ℃, wherein the components of a slagging agent during slagging comprise the following components in percentage by mass: fluorite: 2-3%, iron ore: 40-50%, calcium oxide: 15-20% of calcium carbide: 10-15% of lime and the balance of lime, wherein the particle size of the iron ore is between 30 and 50mm, the lime is in a block shape, and the particle size is between 30 and 50 mm;
s2, when the slag is white, cleaning out the slag, and transferring the slag into an LF refining furnace for refining;
s3, in the refining process, measuring the temperature, feeding an aluminum cake, sampling and analyzing, and performing rough adjustment;
s4, adding silicon carbide in batches for foam slagging, heating to 1560-1580 ℃ when the slag is white and the alkalinity is more than or equal to 2.5, maintaining the reducing atmosphere in the furnace, sampling and analyzing molten steel again after white slag is maintained for 20-25min, fine tuning according to the process requirement, preparing steel after the molten steel components meet the design requirement, and covering the surface of the molten steel with carbonized rice hull covering agent after steel tapping;
s5, tapping and pouring, namely, sedating the molten steel for 8-15min, and then pouring to obtain a semi-finished product of the supporting roller;
s6, opening the semi-finished product of the support roller by adopting a hot box opening process, covering a heating and heat preserving area with a heat preserving agent after opening the box, and sequentially performing diffusion annealing, spheroidizing, normalizing and tempering to obtain the finished product of the support roller;
wherein the diffusion annealing comprises the steps of heating the roller temperature from 450 ℃ for the first time, keeping the temperature for 12 hours when the roller temperature is up to 800 ℃, then heating the roller temperature for the second time, keeping the temperature for 24-36 hours when the roller temperature reaches 1050-1080 ℃, and then air-cooling;
the spheroidizing treatment comprises the steps of feeding a roller Wen Kongleng to 450-500 ℃ into a furnace for heating, keeping the roller temperature to 680-800 ℃, preserving heat for 20-30 hours, cooling the furnace to 500 ℃, discharging the furnace, cooling the furnace to normal temperature, and then performing rough machining, and finishing the process flaw detection;
normalizing the rough machined roller, heating the roller to 660-680 ℃, preserving heat for 6-8h, heating the roller to 960-980 ℃, preserving heat for 32-36h, and performing water mist spray quenching;
the tempering comprises the steps of feeding the steel into a furnace at the temperature of 400-420 ℃ for 6 hours, heating the steel, preserving the heat for 25-30 hours when the temperature of the steel is 540-560 ℃, cooling the steel to the normal temperature, and discharging the steel from the furnace for finish machining;
in the spheroidizing treatment, the temperature is increased to 680-800 ℃ at the speed of 20-30 ℃/h, in the normalizing, the temperature is increased to 660-680 ℃ at the speed of 20-30 ℃/h, the temperature is increased to 960-980 ℃ at the speed of 30-40 ℃/h, and in the tempering, the temperature is increased to 540-560 ℃ at the speed of 14-16 ℃/h;
in the step S5, pouring is carried out by adopting a top pouring technology, the water gap is opened to 1/3 of running water when pouring is carried out, the water gap is fully opened when pouring to the roll body, the water gap is adjusted to 2/3 of running water when pouring to the upper roll neck, the water gap is adjusted to 1/3 of running water when pouring to the effective height of the upper roll neck, and meanwhile, the ladle is lifted to 500-800mm; and in the casting process, an electromagnetic vibrator is adopted to slightly vibrate a supporting roller die, and the vibration frequency is 60-120 times/min.
2. The method for manufacturing the large chromium alloy strip steel supporting roll according to claim 1, wherein: and in the step S3, argon is blown in the whole process in the molten steel refining process, wherein the flow rate of the argon is 3-4m 2/min, and the pressure is 0.15-0.20MPa.
3. The method for manufacturing the large chromium alloy strip steel supporting roll according to claim 1, wherein: and step S4, adding silicon carbide for 2 times, and adding 5-8 Kg/ton of steel each time.
4. The method for manufacturing the large chromium alloy strip steel supporting roll according to claim 1, wherein: in the step S6, the box opening temperature is 560-650 ℃.
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