CN112779466B - Preparation method of chromium alloy strip steel supporting roll - Google Patents

Preparation method of chromium alloy strip steel supporting roll Download PDF

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CN112779466B
CN112779466B CN202011391762.0A CN202011391762A CN112779466B CN 112779466 B CN112779466 B CN 112779466B CN 202011391762 A CN202011391762 A CN 202011391762A CN 112779466 B CN112779466 B CN 112779466B
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supporting roll
temperature
steel
chromium alloy
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CN112779466A (en
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孙建勋
蒋志芳
陈兴
董国卿
曾庆阳
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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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    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/08—Shaking, vibrating, or turning of moulds
    • 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
    • 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
    • C22C33/06—Making ferrous alloys by melting using master alloys
    • 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
    • C22C38/04—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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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

The invention provides a preparation method of a chromium alloy strip steel supporting roll, which comprises the following alloy components in percentage by mass: 0.40-0.80% of C, Si: 0.60 to 0.80 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.020 percent of S, 4.00 to 8.00 percent of Cr, 0.40 to 0.80 percent of Ni, 0.40 to 0.80 percent of Mo, 0.20 to 0.40 percent of V, 0.20 to 0.40 percent of Nb, less than or equal to 0.05 percent of Re, and the balance of Fe and inevitable impurities; and the preparation method comprises the steps of smelting molten steel and slagging in an induction furnace of an intermediate frequency furnace, removing slag and discharging, refining in an LF furnace, pouring steel to obtain a semi-finished supporting roll, and performing annealing, primary tempering and secondary tempering in sequence after a box is opened in a hot mode to obtain a finished supporting roll. The preparation method of the chromium alloy strip steel supporting roll adopts a casting mode to prepare the supporting roll, replaces forging by casting, and can improve the form and distribution of carbide, refine crystal grains of a crystalline structure, improve the wear resistance of the supporting roll, and enhance the tensile strength, impact extrusion toughness and thermal cracking resistance of the supporting roll through a heat treatment process, thereby improving the comprehensive performance of the supporting roll.

Description

Preparation method of chromium alloy strip steel supporting roll
Technical Field
The invention relates to the technical field of roller preparation, in particular to a preparation method of a chromium alloy strip steel supporting roller.
Background
The supporting roll used by the hot-rolled strip steel finishing mill group mainly plays a role of providing pressure support for the working roll during rolling operation. Therefore, the supporting roll firstly needs to have better abrasion rigidity, and secondly, the supporting roll and the working roll form a complex contact line in the rolling operation, so that the long-term contact rolling needs to have higher yield strength, excellent friction toughness and excellent fracture resistance. Therefore, the excellent wear resistance, good friction toughness and strong fatigue and hot cracking resistance of the roller body are the necessary conditions for the supporting roller.
At present, the domestic hot strip finishing mill group is used as a supporting roll, which is mostly made of DG-Cr2-DGCr5 forged steel and high alloy steel, the supporting roll made of the traditional materials is cast to forged, the yield is low, the production period is long, the energy consumption is high, the supporting roll made of the traditional materials is used as a large amount of precious alloy, the consumed resource amount is large, the supporting roll made of the traditional materials is influenced by the rolling environment and is often subjected to alternating bending stress in a complex contact line with a working roll, and friction indentation when the rolled piece passes through can appear on the working surface of the supporting roll due to the interweaving influence of the heat conduction extrusion impact force of the high-temperature strip steel rolled piece, so that the grinding amount of the roll is increased.
Meanwhile, the compressive stress of the surface of the supporting roll and the tensile stress of the core part are mutually acted and are concentrated to two sides of the surface of the roll under the induction of the alternating bending stress, the concentrated stress energy is continuously increased along with the extension of the operation time, and then hot cracks caused by stress expansion can occur, so that the two sides of the surface of the roll are shouldered and peeled off to fall blocks, and the performance of the supporting roll is influenced.
Disclosure of Invention
In view of the above, the present invention is directed to a method for manufacturing a supporting roller of chromium alloy strip steel, so as to improve the performance of the supporting roller.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a preparation method of a chromium alloy strip steel supporting roll comprises the following alloy components in percentage by mass: 0.40-0.80% of C, Si: 0.60 to 0.80 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.020 percent of S, 4.00 to 8.00 percent of Cr, 0.40 to 0.80 percent of Ni, 0.40 to 0.80 percent of Mo, 0.20 to 0.40 percent of V, 0.20 to 0.40 percent of Nb, less than or equal to 0.05 percent of Re, and the balance of Fe and inevitable impurities; and the preparation method comprises the following steps:
a. smelting molten steel in an induction furnace of an intermediate frequency furnace, and slagging when the temperature of the steel reaches 1450 ℃;
b. cleaning out slag when the slag is white, and discharging when the temperature of the steel reaches 1480 ℃;
c. refining in an LF furnace, namely adding a heavy rare earth molten steel modifier during refining, and adding a vanadium alloy and a niobium alloy when the temperature of the steel is up to 1560 ℃;
d. sampling and analyzing, preparing to tap after the components of the molten steel meet the design requirements, and inserting aluminum into the furnace for deoxidation 5min before tapping;
e. tapping, blowing argon in a steel ladle for oscillation, calming for 8-15min, and then pouring to obtain a semi-finished supporting roll;
f. opening the semi-finished supporting roller by adopting a hot box opening process, wrapping mineral wool fibers after opening the box, and sequentially annealing, primary tempering and secondary tempering to obtain a finished supporting roller;
wherein the annealing comprises the steps of preserving heat at 550 ℃ for 4h at 450-;
the primary tempering comprises the steps of preserving heat for 6h at the temperature of 380-;
the secondary tempering comprises the steps of preserving heat for 6 hours at the temperature of more than or equal to 100 ℃, then raising the temperature to 480-520 ℃, preserving heat for 30 hours, and then cooling in a furnace.
Further, the components of the slag former during slag formation in the step a comprise the following components in percentage by mass: fluorite: 3-5%, white quartz sand: 50-80%, crushed iron ore: 10-15% and the balance of lime.
Further, the particle size of the crushed iron ore is 30-50mm, and the particle size of the lime is 20-30 mm.
Furthermore, the grade of the yttrium-based heavy rare earth molten steel alterant is YBZW-6.
Furthermore, the addition ratio of the yttrium-based heavy rare earth molten steel alterant is 3-5 Kg/ton.
Further, in step d, 0.03% of the intercalated aluminum is deoxidized.
Furthermore, in the step e, top pouring is adopted for pouring, a water gap is opened to 1/2 flowing water when pouring is started, the water gap is fully opened when pouring is carried out to the lower roller neck, the water gap is adjusted to 1/3 flowing water when pouring is carried out to the effective height of the upper roller neck, and meanwhile, the ladle is lifted by 500 mm and 800 mm.
Further, when the pouring is finished, the supporting roller die is slightly vibrated by an electromagnetic vibrator, and the vibration frequency is 80-120/min.
Further, in the step f, the box opening temperature is 450-550 ℃, and the thickness of the mineral wool fiber is 15-20 mm.
Further, in the annealing, the temperature is raised to 645 ℃ and 655 ℃ at the speed of 15 ℃/h, and is raised to 850 ℃ and 870 ℃ at the speed of 20 ℃/h; in the primary tempering, the temperature is raised to 480 ℃ at the speed of 8 ℃/h; in the secondary tempering, the temperature is raised to 480-520 ℃ at the speed of 15-18 ℃/h.
Compared with the prior art, the invention has the following advantages:
the preparation method of the chromium alloy strip steel supporting roll adopts a casting mode to prepare the supporting roll, replaces forging by casting, and can improve the form and distribution of carbide, refine crystal grains of a crystalline structure, improve the wear resistance of the supporting roll, and enhance the tensile strength, impact extrusion toughness and thermal cracking resistance of the supporting roll through a heat treatment process, thereby improving the comprehensive performance of the supporting roll.
In addition, in the preparation method, by adding the yttrium-based heavy rare earth molten steel alterant, active elements in the rare earth can be utilized to remove related impurity elements and purify the molten steel, and the adopted slag former component can effectively remove phosphorus and sulfur. During pouring, the height of the ladle is adjusted, so that the pressure of molten steel flowing to the riser can be adjusted, the liquid level can be oscillated, residues can float upwards, and the loose area of the riser structure can be reduced when the molten steel is cooled, solidified and crystallized by utilizing oscillation. In addition, the density of the solidified and crystallized molten steel can be enhanced by vibration after pouring, and loose and shrinkage porosity areas of the whole casting are eliminated.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The embodiment relates to a preparation method of a chromium alloy strip steel supporting roll, which comprises the following alloy components in percentage by mass in the overall design: 0.40-0.80% of C, Si: 0.60 to 0.80 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.020 percent of S, 4.00 to 8.00 percent of Cr, 0.40 to 0.80 percent of Ni, 0.40 to 0.80 percent of Mo, 0.20 to 0.40 percent of V, 0.20 to 0.40 percent of Nb, less than or equal to 0.05 percent of Re, and the balance of Fe and inevitable impurities.
The preparation method of the chromium alloy strip steel supporting roll comprises the steps of smelting molten steel and slagging in an induction furnace of an intermediate frequency furnace, removing slag, discharging, refining in an LF furnace, casting tapping to obtain a supporting roll semi-finished product, and annealing, primary tempering and secondary tempering sequentially after a hot box is opened to obtain a supporting roll finished product.
In detail, in the step of smelting molten steel, an intermediate frequency furnace induction furnace is adopted to smelt the molten steel, slag is formed when the temperature of the molten steel reaches 1450 ℃, and the slag former adopted in slag forming comprises the following components in percentage by mass: fluorite: 3-5%, white quartz sand: 50-80%, crushed iron ore: 10-15% and the balance of lime. The crushed iron ore is generally made of new ore with the iron content of 20-40%, the particle size of the crushed iron ore is 30-50mm, and the particle size of the lime is blocky and is 20-30 mm. And preferably, the composition of the slag former may include 5% fluorite, 70% white quartz sand and 12% crushed iron ore, and also preferably, the particle size of the crushed iron ore is 35mm and the particle size of the lump lime is 30 mm.
In the slag removal and discharge step, specifically, the slag is removed when the slag is white, and the steel is discharged when the temperature of the steel reaches 1480 ℃.
In the LF furnace refining step, a heavy rare earth molten steel modifier is added during refining, and vanadium alloy and niobium alloy are added when the temperature of the steel reaches 1560 ℃. Then, the molten steel is sampled and analyzed, steel tapping is prepared after the components of the molten steel meet the design requirements, and aluminum deoxidation is inserted into the furnace 5min before the steel tapping.
Wherein, the heavy rare earth molten steel alterant can adopt an alterant product with the brand number YBZW-6, and simultaneously, the addition proportion of the yttrium-based heavy rare earth molten steel alterant is 3-5 Kg/ton. Specifically, the deoxidation may be carried out with 0.03% of the aluminum inserted.
In the tapping and pouring step, argon blowing oscillation is carried out in a ladle after tapping to block the suction of molten steel, and pouring is carried out after the operation of calming for 8-15min to obtain a semi-finished supporting roll. At this time, the pouring of this embodiment specifically adopts a top pouring process, and the nozzle is opened to 1/2 flowing water when pouring is started, the nozzle is fully opened when pouring is performed to the lower roller neck, the nozzle is adjusted to 1/3 flowing water when pouring is performed to the effective height of the upper roller neck, and the ladle is simultaneously raised by 500-800 mm.
In addition, when the pouring is finished, the supporting roller die is lightly vibrated by an electromagnetic vibrator, and the vibration frequency is 80-120/min.
When the box is opened thermally, the embodiment specifically comprises the step of opening the supporting roller semi-finished product at the box opening temperature of 450-550 ℃, and the mineral wool fiber with the thickness of 15-20mm is wrapped after the box is opened. And annealing, primary tempering and secondary tempering which are sequentially carried out, wherein the annealing specifically comprises the steps of insulating at 550 ℃ for 4h at 450-.
The first tempering specifically comprises the steps of preserving heat for 6h at the temperature of 380-420 ℃, then raising the temperature to the temperature of 450-480 ℃ at the speed of 8 ℃/h, preserving heat for 30h, and then cooling in a furnace to the temperature of more than or equal to 120 ℃. The secondary tempering comprises the steps of preserving heat for 6 hours at the temperature of more than or equal to 100 ℃, then raising the temperature to 480-520 ℃ at the speed of 15-18 ℃/h, preserving heat for 30 hours, and then cooling the furnace, thereby obtaining the finished supporting roll.
The supporting roll manufacturing method in the embodiment adopts a casting mode to manufacture the supporting roll, replaces forging by casting, and can improve the form and distribution of carbide, refine crystal grains of a crystalline structure, improve the wear resistance of the supporting roll, and enhance the tensile strength, impact extrusion toughness and thermal cracking resistance of the supporting roll through a heat treatment process, thereby improving the comprehensive performance of the supporting roll.
In addition, in the preparation method, by adding the yttrium-based heavy rare earth molten steel alterant, active elements in the rare earth can be utilized to remove related impurity elements and purify the molten steel, and the adopted slag former component can effectively remove phosphorus and sulfur. During pouring, the height of the ladle is adjusted, so that the pressure of molten steel flowing to the feeder head can be adjusted, the liquid level is oscillated, residues can float upwards, and the loose area of the feeder head tissue can be reduced when the molten steel is cooled, solidified and crystallized by utilizing oscillation. And the density of the solidified and crystallized molten steel can be enhanced by vibration after pouring, and loose and shrinkage porosity areas of the whole casting are eliminated. Thereby, the comprehensive performance of the prepared support roller is improved.
The preparation of the backup roll of this example will be further described below in specific preparation examples. In the following preparation examples, the process conditions referred to may be set to the preferred values described above unless otherwise specified.
Preparation example 1
In the preparation example, the alloy components of the support roller comprise the following components in percentage by mass: 0.6% of C, Si: 0.6%, Mn: 0.80%, P: 0.020%, S: 0.015%, Cr 7.00%, Ni 0.6%, Mo 0.50%, V0.30%, Nb 0.2%, Re: 0.03%, and the balance of Fe and inevitable impurities.
And the preparation steps comprise:
step a, smelting molten steel in an induction furnace of an intermediate frequency furnace, and slagging when the temperature of the steel reaches 1450 ℃;
b, cleaning out slag when the molten slag is white, and discharging when the temperature of the steel reaches 1480 ℃;
c, rotating an LF furnace for refining, wherein an yttrium-based heavy rare earth molten steel modifier is added during refining, and a vanadium alloy and a niobium alloy are added when the temperature of the steel reaches 1560 ℃;
d, sampling and analyzing, preparing to discharge steel after the components of the molten steel meet the design requirements, and inserting aluminum into the furnace for deoxidation 5min before the discharge of the steel;
tapping, blowing argon in a steel ladle for oscillation, and casting after calming for 10min to obtain a semi-finished supporting roll;
and f, adopting a hot box opening process to open the semi-finished product of the supporting roller, wrapping the mineral wool fiber after opening the box, and sequentially annealing, primary tempering and secondary tempering to obtain a finished product of the supporting roller.
Wherein the addition ratio of the yttrium-based heavy rare earth molten steel alterant in the step c is 3.5 Kg/ton. And e, in the pouring of the step e, lifting the steel ladle by 700mm, and setting the frequency of the electromagnetic vibrator to be 100 times/min.
In the step f, the temperature of the hot box opening is 500 ℃, and the mineral wool fiber with the thickness of 18mm is wrapped after the box opening.
And the annealing comprises the steps of keeping the temperature at 500 ℃ for 4 hours, then heating to 650 ℃ for 32 hours, then heating to 860 ℃ for 10 hours, continuing heating to Acm line and keeping the temperature at 25 ℃ for 20 hours, and then discharging and spraying for quenching. The primary tempering comprises the steps of keeping the temperature at 390 ℃ for 6h, then heating to 460 ℃ and keeping the temperature for 30h, and then cooling to 120 ℃ in a furnace. The secondary tempering comprises the steps of keeping the temperature at 100 ℃ for 6 hours, then heating to 480 ℃ at the speed of 16 ℃/h, keeping the temperature for 30 hours, and then cooling in a furnace.
Preparation example 2
In the preparation example, the alloy components of the support roller comprise the following components in percentage by mass: 0.4% of C, Si: 0.6%, Mn: 0.60%, P: 0.022%, S: 0.016%, Cr 4.00%, Ni 0.4%, Mo 0.40%, V0.20%, Nb 0.2%, Re: less than or equal to 0.04 percent, and the balance of Fe and inevitable impurities.
And the preparation steps comprise:
step a, smelting molten steel in an induction furnace of an intermediate frequency furnace, and slagging when the temperature of the molten steel reaches 1450 ℃;
b, cleaning out slag when the molten slag is white, and discharging the steel when the temperature of the steel reaches 1480 ℃;
c, rotating to an LF furnace for refining, wherein yttrium-based heavy rare earth molten steel alterant is added during refining, and vanadium alloy and niobium alloy are added when the temperature of the steel reaches 1560 ℃;
d, sampling and analyzing, preparing to discharge steel after the components of the molten steel meet the design requirements, and inserting aluminum into the furnace for deoxidation 5min before the discharge of the steel;
tapping, blowing argon in a ladle for oscillation, and pouring after calming for 12min to obtain a semi-finished supporting roll;
and f, adopting a hot box opening process to open the semi-finished product of the supporting roller, wrapping the mineral wool fiber after opening the box, and sequentially annealing, primary tempering and secondary tempering to obtain a finished product of the supporting roller.
Wherein the addition proportion of the yttrium-based heavy rare earth molten steel alterant in the step c is 3.5 Kg/ton. And e, in the pouring of the step e, lifting the steel ladle by 700mm, and setting the frequency of the electromagnetic vibrator to be 100 times/min.
And f, opening the box at 455 ℃ and wrapping the mineral wool fibers with the thickness of 18mm after opening the box.
And the annealing comprises the steps of keeping the temperature at 455 ℃ for 4 hours, then heating to 645 ℃ for 32 hours, then heating to 855 ℃ for 10 hours, continuing heating to the Acm line and keeping the temperature at 30 ℃ for 20 hours, and then discharging and spraying and quenching. The primary tempering comprises the steps of keeping the temperature at 380 ℃ for 6 hours, then heating to 450 ℃ and keeping the temperature for 30 hours, and then cooling to 120 ℃ in a furnace. The secondary tempering comprises the steps of keeping the temperature at 100 ℃ for 6 hours, then heating to 480 ℃ at the speed of 15 ℃/h, keeping the temperature for 30 hours, and then cooling in a furnace.
Preparation example 3
In the preparation example, the alloy components of the support roller comprise the following components in percentage by mass: 0.8% of C, Si: 0.8%, Mn: 0.80%, P: 0.018%, S: 0.014%, Cr 7.00%, Ni 0.8%, Mo 0.80, V0.30%, Nb 0.4%, Re: 0.03%, and the balance of Fe and inevitable impurities.
And the preparation steps comprise:
step a, smelting molten steel in an induction furnace of an intermediate frequency furnace, and slagging when the temperature of the molten steel reaches 1450 ℃;
b, cleaning out slag when the molten slag is white, and discharging when the temperature of the steel reaches 1480 ℃;
c, rotating an LF furnace for refining, wherein an yttrium-based heavy rare earth molten steel modifier is added during refining, and a vanadium alloy and a niobium alloy are added when the temperature of the steel reaches 1560 ℃;
d, sampling and analyzing, preparing to discharge steel after the components of the molten steel meet the design requirements, and inserting aluminum into the furnace for deoxidation 5min before the discharge of the steel;
tapping, blowing argon in a steel ladle for oscillation, and casting after calming for 10min to obtain a semi-finished supporting roll;
and f, adopting a hot box opening process to open the semi-finished product of the supporting roller, wrapping the mineral wool fiber after opening the box, and sequentially annealing, primary tempering and secondary tempering to obtain a finished product of the supporting roller.
Wherein the addition ratio of the yttrium-based heavy rare earth molten steel alterant in the step c is 3.5 Kg/ton. And e, in the pouring of the step e, lifting the steel ladle by 700mm, and setting the frequency of the electromagnetic vibrator to be 100 times/min.
In the step f, the temperature of the hot box opening is 520 ℃, and the mineral wool fiber with the thickness of 18mm is wrapped after the box opening.
The annealing comprises the steps of keeping the temperature at 520 ℃ for 4 hours, then heating to 655 ℃ for 32 hours, then heating to 865 ℃ for 10 hours, continuing heating to Acm line and 30 ℃ for 20 hours, and then discharging and spraying for quenching. The primary tempering comprises the steps of keeping the temperature at 400 ℃ for 6 hours, then heating to 480 ℃ and keeping the temperature for 30 hours, and then furnace cooling to 120 ℃. The secondary tempering comprises the steps of keeping the temperature at 100 ℃ for 6 hours, then heating to 500 ℃ at the speed of 16 ℃/h, keeping the temperature for 30 hours, and then furnace cooling.
The hardness tests of the supporting rolls prepared in the three preparation examples respectively show that the hardness of the roll surface of the supporting roll is 70-75HSD and the hardness of the roll neck is 42-48HSD, and the tensile strength of the supporting roll prepared in each preparation example is tested to show that the tensile strength of the supporting roll is not less than 950 MPa. In addition, by observing the metallographic structure of the prepared supporting roller, the metallographic structure of the supporting roller can be found to be fine grained metal carbide + tempered sorbite + bainite + a small amount of martensite.
As can be seen from the preparation examples, the supporting roll prepared by the preparation method has better roll surface hardness and roll neck hardness, higher tensile strength and better metallographic structure form. Therefore, the supporting roll prepared by the preparation method has better comprehensive performance, and the millimeter manufacturing amount of the supporting roll prepared by the preparation method is improved by more than 3 mm compared with that of the traditional supporting roll when the supporting roll is used for hot rolling strip steel, so that better economic benefit and social benefit can be obtained.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (7)

1. A preparation method of a chromium alloy strip steel supporting roll is characterized by comprising the following steps: the chromium alloy strip steel supporting roll is used for a hot strip steel finishing mill group, and the chromium alloy strip steel supporting roll comprises the following alloy components in percentage by mass: 0.80% of C, Si: 0.60 to 0.80 percent of Mn, less than or equal to 0.025 percent of P, less than or equal to 0.020 percent of S, 7.00 to 8.00 percent of Cr, 0.40 to 0.80 percent of Ni, 0.40 to 0.80 percent of Mo, 0.20 to 0.40 percent of V, 0.20 to 0.40 percent of Nb, less than or equal to 0.05 percent of Re, and the balance of Fe and inevitable impurities;
the preparation method comprises the following steps:
a. smelting molten steel in an induction furnace of an intermediate frequency furnace, and slagging when the temperature of the steel reaches 1450 ℃;
b. cleaning out slag when the slag is white, and discharging when the temperature of the steel reaches 1480 ℃;
c. refining in an LF furnace, namely adding an yttrium-based heavy rare earth molten steel modifier during refining, and adding a vanadium alloy and a niobium alloy when the temperature of the steel reaches 1560 ℃;
d. sampling and analyzing, preparing to tap after the components of the molten steel meet the design requirements, and inserting aluminum into the furnace for deoxidation 5min before tapping;
e. tapping, blowing argon in a steel ladle for oscillation, calming for 8-15min, and then pouring to obtain a semi-finished supporting roll;
f. opening the semi-finished supporting roller by adopting a hot box opening process, wrapping mineral wool fibers after opening the box, and sequentially annealing, primary tempering and secondary tempering to obtain a finished supporting roller;
wherein the annealing comprises the steps of preserving heat at 550 ℃ for 4h at 450-;
the primary tempering comprises the steps of preserving heat for 6h at the temperature of 380-;
the secondary tempering comprises the steps of preserving heat for 6 hours at the temperature of more than or equal to 100 ℃, then raising the temperature to 480-520 ℃, preserving heat for 30 hours, and then cooling in a furnace;
step e, pouring by adopting a top pouring process, wherein a water gap is opened to 1/2 flowing water when pouring is started, the water gap is fully opened when pouring is carried out to a lower roller neck, the water gap is adjusted to 1/3 flowing water when pouring is carried out to the effective height of an upper roller neck, the ladle is lifted by 500-800mm, and when pouring is finished, an electromagnetic vibrator is adopted to slightly vibrate a supporting roller section mould with the vibration frequency of 80-120/min;
in the annealing, the temperature is raised to 645 ℃ and 870 ℃ at the speed of 15 ℃/h and is raised to 850 ℃ and h at the speed of 20 ℃/h; in the primary tempering, the temperature is raised to 450-480 ℃ at the speed of 8 ℃/h; in the secondary tempering, the temperature is raised to 480-520 ℃ at the speed of 15-18 ℃/h.
2. The method for manufacturing a chromium alloy strip steel backup roll according to claim 1, characterized in that: the slag former during slag forming in the step a comprises the following components in percentage by mass: fluorite: 3-5%, white quartz sand: 50-80%, crushed iron ore: 10-15% and the balance of lime.
3. The method for manufacturing a chromium alloy strip steel backup roll according to claim 2, characterized in that: the particle size of the crushed iron ore is 30-50mm, and the particle size of the lime is 20-30 mm.
4. The method for manufacturing a chromium alloy strip steel backup roll according to claim 1, characterized in that: the grade of the yttrium-based heavy rare earth molten steel alterant is YBZW-6.
5. The method for manufacturing a chromium alloy strip steel supporting roll according to claim 4, characterized in that: the addition proportion of the yttrium-based heavy rare earth molten steel alterant is 3-5 Kg/ton.
6. The method for manufacturing a chromium alloy strip steel supporting roll according to claim 1, wherein the method comprises the following steps: in step d, 0.03% of the intercalated aluminum is deoxidized.
7. The method for manufacturing a chromium alloy strip steel supporting roll according to claim 1, wherein the method comprises the following steps: in the step f, the box opening temperature is 450-550 ℃, and the thickness of the mineral wool fiber is 15-20 mm.
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