CN116694992A - High-strength lightweight wear-resistant steel for stirring tank and manufacturing method thereof - Google Patents

High-strength lightweight wear-resistant steel for stirring tank and manufacturing method thereof Download PDF

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CN116694992A
CN116694992A CN202310614197.7A CN202310614197A CN116694992A CN 116694992 A CN116694992 A CN 116694992A CN 202310614197 A CN202310614197 A CN 202310614197A CN 116694992 A CN116694992 A CN 116694992A
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equal
percent
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steel
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邓伟
杨新泉
李慕耘
唐树平
孙振
卢震亚
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Wuhan Iron and Steel Co Ltd
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Wuhan Iron and Steel 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
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
    • B22D11/055—Cooling the moulds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • B22D11/20—Controlling or regulating processes or operations for removing cast stock
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
    • 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
    • C21C7/064—Dephosphorising; Desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • 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
    • C22C38/04—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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • 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
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Abstract

The invention discloses high-strength lightweight wear-resistant steel for a stirring tank, which is characterized by comprising the following chemical components in percentage by weight: c:0.13 to 0.15 percent, si:1.10 to 1.30 percent of Mn:1.70 to 1.90 percent, P: less than or equal to 0.015 percent, S: less than or equal to 0.0015 percent, alt:0.45 to 0.55 percent, ti: 0.01-0.025%, N is less than or equal to 0.0050%, B is less than or equal to 0.0005%, T [ O ] is less than or equal to 0.0030%, and the rest is Fe and unavoidable impurities. The invention also discloses a preparation method of the wear-resistant steel. The wear-resistant steel prepared by the method has the yield strength of 550-850MPa, the tensile strength of 950-1100MPa, the elongation A of more than or equal to 15%, the hardness of 300-450HB and the thickness specification of 3-6mm, solves the contradiction between low yield strength and high tensile strength, and has the advantages of high strength and light weight.

Description

High-strength lightweight wear-resistant steel for stirring tank and manufacturing method thereof
Technical Field
The invention belongs to the technical field of steel materials, and particularly relates to high-strength lightweight wear-resistant steel for a stirring tank and a manufacturing method thereof.
Background
In recent years, the commercial concrete mixer truck industry typified by the mixer tank industry has a strong demand for high strength and light weight, and the demand for thin-specification wear-resistant steel has been greatly increased. In order to meet urgent demands of users, development of high-strength lightweight wear-resistant steel is urgently needed.
The existing wear-resistant steel for the stirring tank has the defect that the requirements of high strength, high wear resistance, high service life and light weight cannot be met. The concrete mixer truck has larger abrasion consumption on the steel of the mixing tank in the mixing process, and increases the thickness of the steel plate in order to reduce abrasion and prolong the service period, so that the mixer truck has heavy load, causes a series of resource waste under high load, has shorter service period in order to reduce load, and has safety risk. Some wear-resistant steel components are C, si, mn, nb, ni, cr, mo, V, B, and the like, so that the alloy cost is high. Such as: the Chinese patent application numbers are CN91108342.1, CN93117604.2, CN 951010449. X, CN96118610.0, CN95103151.1, CN96108157.0 and the like, and one or more of expensive alloys such as Mo, nb, V, ni and the like are added, so that the cost is high. Therefore, development of the steel for the stirring tank with high strength, high wear resistance, high service life and light weight is significant.
Disclosure of Invention
The invention aims to overcome the defects in the above documents and provide high-strength lightweight wear-resistant steel for a stirring tank and a manufacturing method thereof, and particularly relates to high-strength lightweight wear-resistant steel with yield strength of 550-850MPa, tensile strength of 950-1100MPa, elongation A of more than or equal to 15%, hardness of 300-450HB and thickness specification of 3-6 mm.
In order to achieve the above purpose, the invention adopts the following technical scheme: the high-strength lightweight wear-resistant steel for the stirring tank comprises the following chemical components in percentage by weight: c:0.13 to 0.15 percent, si:1.10 to 1.30 percent of Mn:1.70 to 1.90 percent, P: less than or equal to 0.015 percent, S: less than or equal to 0.0015 percent, alt:0.45 to 0.55 percent, ti: 0.01-0.025%, N is less than or equal to 0.0050%, B is less than or equal to 0.0005%, T [ O ] is less than or equal to 0.0030%, and the rest is Fe and unavoidable impurities.
Preferably, the chemical components and the weight percentage content are as follows:
C：0.135～0.145％，Si：1.15～1.25％，Mn：1.75～1.85％，P：≤0.012％，S：≤0.0010％，Alt：0.47～0.53％，Ti：0.012～0.022％，N≤0.0040％，B≤0.0004％。
the invention also provides a preparation method of the high-strength lightweight wear-resistant steel for the stirring tank, which mainly comprises the following steps:
the process flow is as follows: KR molten iron desulfurization-converter smelting-argon blowing-LF refining (ladle furnace) -and
RH vacuum treatment, continuous casting blank forming, slab heating, rolling, cooling and coiling.
1) The KR method for desulfurizing molten iron, wherein more than three slag skimming treatments are carried out during the desulfurization, wherein the slag skimming refers to slag before skimming or slag after skimming, the slag before skimming is not more than the slag after skimming and not less than once, and the residence time between every two slag after skimming is not less than 6min; the exposed surface is not less than 90%; s in the desulfurized molten iron is less than or equal to 0.001%;
the desulfurization and slag skimming of the molten iron are carried out cleanly, so that the sulfur content of the molten iron entering the converter is reduced, and the subsequent steel slag reversion caused by incomplete slag skimming is prevented.
2) Smelting in a converter, controlling the end point temperature of the converter to 1630-1650 ℃ and the end point oxygen to 0.050-0.075%; and (3) tapping steel from the converter, adding aluminum iron for deoxidization completely, and controlling Alt in the steel: 0.100 to 0.130 percent; adding ferrosilicon alloy and ferromanganese alloy, wherein boron content in the added ferrosilicon alloy is less than or equal to 0.005%, and Si content is: 75-78%, ferrosilicon alloy addition 15-18 kg/t.s, controlling molten steel B content less than or equal to 0.0001%, converter tapping slag amount less than or equal to 40mm.
3) Argon is blown to the bottom of the molten steel through an argon blowing station.
4) Molten steel is subjected to deep desulfurization treatment by a ladle furnace, aluminum particles are added in slagging in the early stage of desulfurization of the ladle furnace, and aluminum wires are fed in the later stage. Controlling S in molten steel to be less than or equal to 0.001 percent. Controlling the smelting time of the ladle furnace to be less than or equal to 45 minutes. Controlling the content of B in molten steel to be less than or equal to 0.0003 percent.
5) The molten steel is subjected to cyclic degassing and deslagging treatment by a vacuum furnace, and components are finely adjusted by adding carburant, ferrosilicon alloy, ferromanganese alloy, ferrotitanium alloy and aluminum particles, so that the contents of C, si, mn, alt and Ti are consistent with the contents of wear-resistant steel in a final product; the vacuum circulation time is 30-35 minutes, the vacuum degree is controlled to be less than or equal to 15Pa, and the vacuum ending temperature is controlled to be 1536-1546 ℃. The Si and Alt components of the invention are higher than those of the conventional wear-resistant steel, the vacuum ferrosilicon alloy and aluminum pellets are added in larger quantity, the circulation time and vacuum degree parameters are strictly controlled in the vacuum circulation process, the nitrogen content in the steel can be further reduced, the harmful impurities and gas are further removed, the impurities generated by adding the alloy and the aluminum pellets are reduced, and the purity of molten steel is improved, thereby improving the wear resistance of the steel.
The difficulty in the smelting process is that B in molten steel is controlled to be less than or equal to 0.0005 percent (preferably B is less than or equal to 0.0004 percent):
a) In the smelting process of the converter, the top-bottom combined blowing of the converter utilizes the strong boron removal effect of oxygen blowing of the converter, so that boron in molten steel is fully oxidized under the strong oxidation effect to enable oxidation products to enter slag, and the B in the molten steel is controlled to be less than or equal to 0.0001 percent. b) The slag discharging amount is strictly controlled in the converter tapping process, and is less than or equal to 40mm. c) The alloy with low boron content is selected, so that the boron increase of the alloy is reduced, the Si content of the steel is higher, the alloy addition amount is maximum, and the alloy contains a certain B impurity element to cause the B increase of molten steel, so that the ferrosilicon alloy with extremely low boron content is selected. d) Although the slag discharge amount is strictly controlled in the tapping process of the converter, a part of converter slag still enters the ladle, which is unavoidable. In the process of deep desulfurization treatment of molten steel by a ladle furnace, a part of boron returns to the molten steel to increase boron in the molten steel, boron in slag is controlled to return to the molten steel, aluminum particles are adopted in desulfurization of reducing slag, when sulfur is removed to less than 0.0015%, aluminum wires fed by a wire feeder directly pass through a slag layer, and B elements in slag are prevented from being further reduced to the molten steel due to the slag layer when the aluminum particles are added. e) The consumption of the additive containing boron elements of the magnesia carbon bricks at the ladle slag line is controlled, so that the B content of the magnesia carbon bricks is less than or equal to 0.2%, the magnesia carbon bricks are prevented from being decomposed due to serious erosion of the ladle slag line when molten steel is smelted by a ladle furnace, the boron elements contained in the magnesia carbon bricks are brought into the molten steel to increase B content of the molten steel, the smelting time of the ladle furnace is controlled to be less than or equal to 45 minutes, and the erosion of the molten steel to the ladle slag line is reduced. Finally controlling the B in the molten steel to be less than or equal to 0.0003 percent when the production of the ladle furnace is finished.
6) The invention contains higher Si and Al components, particularly adopts higher Al components and does not contain expensive Mo, nb, V and other alloys, so that the quality assurance of the continuous casting billet is critical and is a technical problem. The conventional wear-resistant steel controls the Alt component to be in a lower range, such as below 0.050 percent (but the Alt component is controlled to be between 0.45 and 0.55 percent), and expensive Mo, nb, V and other alloys are added, namely, the higher the Al component is, the more easily the continuous casting blank is subjected to defects such as longitudinal cracks, edge cracks, segregation, surface scars, pits and the like of the casting blank, so that the casting blank is easy to scrap. The conventional method cannot overcome this difficulty. The related parameters of continuous casting steady casting are key, the parameters of the crystallizer casting powder are difficult points, the low-alkalinity, higher-viscosity and low-melting-point crystallizer casting powder is selected in the continuous casting process, the alkalinity is 0.55-0.75, the viscosity is 0.107-0.207 Pa.S (the temperature is 1300 ℃), the melting point is 944-1044 ℃, the taper of the crystallizer is set to 1.18-1.22%, the cooling water volume of the crystallizer adopts medium-strength cooling water volume, the wide-surface cooling water flow is 3400-3600L/min, and the narrow-surface cooling water flow of the crystallizer is 600-620L/min.
7) The invention contains higher Si and Al components, and in order to avoid the defects of cracks, segregation and the like of casting blanks in the casting process, the low superheat degree is controlled in the continuous casting process, the superheat degree is controlled at 5-15 ℃, and the tundish temperature is controlled at 1511-1521 ℃. The superheat degree of the traditional wear-resistant steel is controlled to be between 10 and 25 ℃ and is higher than that of the traditional wear-resistant steel. Because the lower the degree of superheat, the better the control over center segregation during casting, but the lower the degree of superheat, the closer the tundish temperature is to the liquidus temperature of the molten steel, resulting in an interruption of solidification of the molten steel during casting.
8) The invention contains higher Si and Al components, and in order to avoid steel leakage in the casting process, the lower drawing speed is controlled in the continuous casting process, and the drawing speed is controlled to be 0.9-1.1 m/min. In the continuous casting process, the fluctuation range of the molten steel surface of the crystallizer is controlled within +/-3 mm.
The continuous casting steady casting parameters of the invention are technical problems, the molten steel contains higher Si and Al components, the alkalinity, viscosity and melting point of the mold flux are controlled, and the matching of low superheat degree, low drawing speed and cooling speed of the mold is key. On the other hand, in combination with the control of the surface temperature of the casting blank, the surface temperature of the casting blank is controlled in sections according to different casting flow lengths, as follows:
the control method is different from the traditional casting method, so that the technical problem can be overcome, and the defects of a casting blank are avoided.
9) Heating the slab to 1280-1320 ℃, preserving heat, soaking, and then rolling, wherein the rough rolling temperature is 1080-1120 ℃, and the finish rolling temperature is 860-900 ℃; the coiling temperature is 110-150 ℃.
The action mechanism of each element in the invention is as follows:
carbon (C): is an important element affecting the strength, hardness, toughness and hardenability of the wear-resistant steel, and forms carbide to improve the hardness and wear resistance of the steel. Is also the most important element affecting the microstructure of the steel, which is ferrite + martensite, but too high carbon reduces the plasticity and toughness of the steel. The preferable addition amount of carbon is 0.13 to 0.15%, and preferable C:0.135 to 0.145 percent.
Manganese (Mn): the conventional strengthening elements are relatively low in price, the strength and hardness of the wear-resistant steel can be improved, the hardenability of the steel can be improved, and the steel can easily reach a martensitic structure after quenching. However, the higher the manganese, the lower the plasticity and weldability of the steel, and center segregation may occur. The preferable addition amount of Mn is 1.70-1.90%, preferable Mn:1.75 to 1.85 percent.
Silicon (Si): silicon exists in ferrite in a solid solution form, can reduce an austenite phase region, can obviously improve the strength and hardness of steel, improves the wear resistance, can improve the yield ratio and fatigue strength of the steel, and can promote coarsening of ferrite grains and reduce coercive force. However, if the silicon content is too high, the plasticity and the weldability are reduced, and the preferable silicon content is 1.10 to 1.30%, preferably Si:1.15 to 1.25 percent.
Titanium (Ti): the addition of small amounts of titanium may refine the grain and precipitate strengthening to improve the strength of the wear resistant steel. Titanium, nitrogen, oxygen and carbon have extremely strong affinity, and are good deoxidizing and degassing agents and elements for fixing nitrogen and carbon, titanium carbide particles can be formed to prevent grain growth, but the hardenability of steel is reduced due to the fact that titanium is high, the addition amount of the titanium is 0.010-0.025%, and preferable Ti: 0.012-0.022%.
Aluminum (Al): aluminum is a main deoxidizing element in steel, and aluminum and nitrogen or oxygen generate effective fine dispersoids to inhibit grain growth, so that the grains can be refined, and nitrogen in the steel can be fixed, thereby obviously improving the impact toughness of the steel and reducing the cold embrittlement tendency and the aging tendency. Aluminum generates an effective surface hardening layer by low-temperature diffusion and nitridation of nitrogen, so that the hardness and strength of steel are increased, and the wear resistance and oxidation resistance of the steel are improved by the aluminum, but the hot workability and welding performance of the steel are affected by the disadvantage of the aluminum. Unlike traditional wear-resistant steel, the invention has the advantages that the Al content is 0.45-0.55%, and the preferable Alt:0.47 to 0.53 percent.
Boron (B): the invention takes B as a harmful element to obtain ferrite and martensite structure, and when the B content exceeds 0.0005%, the microstructure of the steel is easily converted into bainite. Boron, nitrogen and oxygen have strong affinity, have strong interaction with various defects such as dislocation, vacancy and the like, and can be combined with S, C and other elements to form various types of inclusions. For the stirring tank steel, trace B in the steel plate can lead to high weld hardness of the steel plate after welding, so that fatigue cracks are easy to be caused when the stirring tank steel is in long-term service, and the service life is seriously influenced. And the welding process is also prone to problems. Thus, the present invention requires B.ltoreq.0.0005%, preferably B.ltoreq.0.0004%.
Phosphorus (P): p is easy to cause phosphorus dendrite segregation of casting blank, increase the brittleness of grain boundary, increase crack sensitivity and generate internal cracking; phosphorus also deteriorates toughness, plasticity, and "cold embrittlement" of steel at low temperature, and deteriorates weldability, so that the phosphorus content in steel should be reduced as much as possible.
Sulfur (S) sulfur is liable to cause thermal embrittlement, which reduces ductility and toughness of steel, and reduces weldability; the sulfur content in the steel should be minimized.
The traditional wear-resistant steel adopts C, si, mn, nb, ni, cu, cr, mo, V, B and the like, so that more noble alloy elements are added, and the alloy cost is high. The invention adopts a component system of medium and low C-Si-Al-micro Ti, has low alloy cost, takes B element as a harmful element, controls the content below 0.0005 percent, ensures that the microstructure of the steel is ferrite and martensite, prevents bainite transformation, ensures that the wear resistance of the wear-resistant steel with the microstructure of ferrite and martensite under the sliding wear condition and the impact abrasive wear condition is superior to that of the bainite wear-resistant steel, and ensures that the trace B in the steel plate can lead to high weld hardness of the steel plate after welding, so that fatigue cracks are easy to be caused when the stirring tank steel is in service for a long time, and the welding process is also easy to cause problems. Meanwhile, the tempering brittleness temperature of the steel can be transferred to a higher temperature by containing higher Si and Al elements, the tensile strength of the steel is not reduced while the yield strength of the steel is reduced, the contradiction between low yield strength and high tensile strength is solved, the low yield strength of the stirring tank steel is used for facilitating steel processing, and the high tensile strength is used for prolonging the service life of the stirring tank.
Detailed Description
In order that those skilled in the art will better understand the technical scheme of the present invention, the present invention will be described in further detail with reference to specific examples.
The wear-resistant steel is prepared by the following steps:
the process flow is as follows: KR molten iron desulfurization-converter smelting-argon blowing-LF refining (ladle furnace) -and
RH vacuum treatment, continuous casting blank forming, slab heating, rolling, cooling and coiling.
1) The KR method for desulfurizing molten iron, wherein three slag skimming treatments are carried out during the desulfurization, wherein the slag skimming treatment is carried out before one time, the slag skimming treatment is carried out after two times, and the residence time between the slag skimming treatments is not less than 6min; the exposed surface is not less than 90%; s in the desulfurized molten iron is less than or equal to 0.001 percent.
2) Smelting in a converter, controlling the end point temperature of the converter to 1630-1650 ℃ and the end point oxygen to 0.050-0.075%; and (3) tapping steel from the converter, adding aluminum iron for deoxidization completely, and controlling Alt in the steel: 0.100 to 0.130 percent; adding ferrosilicon alloy and ferromanganese alloy, wherein boron content in the added ferrosilicon alloy is less than or equal to 0.005%, and Si content is: 75-78%, ferrosilicon alloy addition 15-18 kg/t.s, controlling molten steel B content less than or equal to 0.0001%, converter tapping slag amount less than or equal to 40mm.
3) Argon is blown to the bottom of the molten steel through an argon blowing station.
4) Molten steel is subjected to deep desulfurization treatment by a ladle furnace, aluminum particles are added in slagging in the early stage of desulfurization of the ladle furnace, and aluminum wires are fed in the later stage. Controlling S in molten steel to be less than or equal to 0.001 percent. Controlling the smelting time of the ladle furnace to be less than or equal to 45 minutes. Controlling the content of B in molten steel to be less than or equal to 0.0003 percent.
5) The molten steel is subjected to cyclic degassing and deslagging treatment by a vacuum furnace, and components are finely adjusted by adding carburant, ferrosilicon alloy, ferromanganese alloy, ferrotitanium alloy and aluminum particles, so that the contents of C, si, mn, alt and Ti are consistent with the contents of wear-resistant steel in a final product; the vacuum circulation time is 30-35 minutes, the vacuum degree is controlled to be less than or equal to 15Pa, and the vacuum ending temperature is controlled to be 1536-1546 ℃. The Si and Alt components of the invention are higher than those of the conventional wear-resistant steel, the vacuum ferrosilicon alloy and aluminum pellets are added in larger quantity, the circulation time and vacuum degree parameters are strictly controlled in the vacuum circulation process, the nitrogen content in the steel can be further reduced, the harmful impurities and gas are further removed, the impurities generated by adding the alloy and the aluminum pellets are reduced, and the purity of molten steel is improved, thereby improving the wear resistance of the steel.
6) The invention selects low alkalinity, higher viscosity and low melting point crystallizer casting powder in the continuous casting process, the alkalinity is 0.55-0.75, the viscosity is 0.107-0.207 Pa.S (when the temperature is 1300 ℃), the melting point is 944-1044 ℃, the taper of the crystallizer is set to 1.18-1.22%, the cooling water quantity of the crystallizer adopts middle strength cooling water quantity, the wide cooling water flow quantity is 3400-3600L/min, and the narrow cooling water flow quantity of the crystallizer is 600-620L/min.
7) The low superheat degree is controlled in the continuous casting process, the superheat degree is controlled at 5-15 ℃, and the tundish temperature is controlled at 1511-1521 ℃.
8) The lower drawing speed is controlled in the continuous casting process, and the drawing speed is controlled to be 0.9-1.1 m/min. In the continuous casting process, the fluctuation range of the molten steel surface of the crystallizer is controlled within +/-3 mm.
In combination with the control of the surface temperature of the casting blank, the surface temperature of the casting blank is controlled in sections according to different casting flow lengths, and the following steps are realized:
9) Heating the slab to 1280-1320 ℃, preserving heat, soaking, and then rolling, wherein the rough rolling temperature is 1080-1120 ℃, and the finish rolling temperature is 860-900 ℃; the coiling temperature is 110-150 ℃.
The components, processes and properties of the examples of the present invention are shown in tables 1 to 4, respectively.
As can be seen from tables 1 to 4, the high-strength lightweight wear-resistant steel for the stirring tank, which is prepared by the invention, specifically has the yield strength of 550-850MPa, the tensile strength of 950-1100MPa, the elongation A of more than or equal to 15%, the hardness of 250-450 HB and the thickness specification of 3-6 mm. Can completely meet the performance requirements of the high-strength lightweight wear-resistant steel.
The above examples are only the best illustration and are not limiting of the embodiments of the invention.
TABLE 1 list of component values (wt.%)
TABLE 2 list of major steelmaking process parameters for each example and comparative example of the invention
TABLE 3 list of major steelmaking process parameters for each example and comparative example of the invention
TABLE 4 list of major steelmaking process parameters for each example and comparative example of the invention
TABLE 5 actual measurement of the values corresponding to the casting flow length and the surface temperature of the cast slab during continuous casting in each example and comparative example of the present invention
TABLE 6 Main Hot Rolling Process parameter List (. Degree. C.) for each example of the present invention and comparative example
TABLE 7 statistical tables of the main Performance test for each of the examples and comparative examples of the present invention
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Claims (3)

1. The high-strength lightweight wear-resistant steel for the stirring tank is characterized by comprising the following chemical components in percentage by weight: c:0.13 to 0.15 percent, si:1.10 to 1.30 percent of Mn:1.70 to 1.90 percent, P: less than or equal to 0.015 percent, S: less than or equal to 0.0015 percent, alt:0.45 to 0.55 percent, ti: 0.01-0.025%, N is less than or equal to 0.0050%, B is less than or equal to 0.0005%, T [ O ] is less than or equal to 0.0030%, and the rest is Fe and unavoidable impurities.
2. The high-strength lightweight wear-resistant steel for a stirring tank according to claim 1, wherein the high-strength lightweight wear-resistant steel for a stirring tank comprises the following chemical components in percentage by weight:
C：0.135～0.145％，Si：1.15～1.25％，Mn：1.75～1.85％，P：≤
0.012％，S：≤0.0010％，Alt：0.47～0.53％，Ti：0.012～0.022％，N≤
0.0040％，B≤0.0004％。
3. the method for preparing the high-strength lightweight wear-resistant steel for a stirring tank according to any one of claims 1 to 2, which is characterized by comprising the steps of KR molten iron desulfurization, converter smelting, argon blowing, LF refining, RH vacuum treatment, continuous casting into a billet, slab heating, rolling, cooling and coiling;
in the KR method molten iron desulfurization step, more than three slag skimming treatments are carried out during the desulfurization, wherein the slag skimming refers to slag before or after skimming, the slag skimming frequency is not more than the slag skimming frequency and not less than once, and the residence time between every two slag skimming is not less than 6min; the exposed surface is not less than 90%; s in the desulfurized molten iron is less than or equal to 0.001%;
in the converter smelting step, the end point temperature of the converter is controlled to 1630-1650 ℃ and the end point oxygen is controlled to be 0.050-0.075; and (3) tapping steel from the converter, adding aluminum iron for deoxidization completely, and controlling Alt in the steel: 0.100 to 0.130 percent; adding ferrosilicon alloy and ferromanganese alloy, wherein the boron content in the added ferrosilicon alloy is less than or equal to 0.005%, and Si is contained: 75-78%, ferrosilicon addition 15-18 kg/t.s, controlling molten steel B content less than or equal to 0.0001%, converter tapping slag amount less than or equal to 40mm;
in the LF refining step, aluminum particles are added in slagging in the earlier stage of desulfurization, aluminum wires are fed in the later stage, S in molten steel is controlled to be less than or equal to 0.001%, the smelting time of a ladle furnace is controlled to be less than or equal to 45 minutes, and the content of B in molten steel is controlled to be less than or equal to 0.0003%.
In the RH vacuum treatment step, components are finely adjusted by adding carburant, ferrosilicon alloy, ferromanganese alloy, ferrotitanium alloy and aluminum particles, so that C:0.135 to 0.145 percent, si:1.15 to 1.25 percent, mn:1.75 to 1.85 percent, alt:0.47 to 0.53 percent, ti:0.012 to 0.022; the vacuum circulation time is 30-35 minutes, the vacuum degree is controlled to be less than or equal to 15Pa, and the vacuum ending temperature is controlled to be 1536-1546 ℃;
in the continuous casting and blank forming step, the alkalinity of the selected crystallizer casting powder is 0.55-0.75, the viscosity at 1300 ℃ is 0.107-0.207 Pa.S, the melting point is 944-1044 ℃, the taper of the crystallizer is set to be 1.18-1.22%, the cooling water flow rate of the wide surface of the crystallizer is 3400-3600L/min, and the cooling water flow rate of the narrow surface is 600-620L/min; the superheat degree of casting is controlled to be 5-15 ℃, and the temperature of the tundish is controlled to be 1511-1521 ℃; the casting speed of the drawn blank is controlled to be 0.9-1.1 m/min, and the fluctuation range of the molten steel surface of the crystallizer is controlled to be within +/-3 mm;
in the continuous casting and blank forming step, the surface temperature of the casting blank is controlled in sections according to different casting flow lengths, wherein the casting flow lengths are sequentially 0, 0.333, 0.417, 0.5, 0.667, 0.833, 0.967, 1.367, 2.333, 3.4, 4.833, 7.167, 9.0, 20.5 and 40m, and the casting blank surface temperature control ranges are sequentially 1343-1349, 1105-1111, 1087-1093, 1072-1078, 1053-1059, 1039-1045, 1029-1035, 1017-1023, 1001-1007, 987-993, 975-981, 961-967, 954-960, 929-935 and 897-903;
in the rolling step, the plate blank is heated to 1280-1320 ℃, then is subjected to heat preservation and soaking, and is rolled, the rough rolling temperature is 1080-1120 ℃, and the finish rolling temperature is 860-900 ℃; the coiling temperature is 110-150 ℃.
CN202310614197.7A 2023-05-29 2023-05-29 High-strength lightweight wear-resistant steel for stirring tank and manufacturing method thereof Pending CN116694992A (en)

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