WO2021052315A1 - Tôle/bande d'acier 30crmo laminée à chaud et son procédé de production - Google Patents

Tôle/bande d'acier 30crmo laminée à chaud et son procédé de production Download PDF

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WO2021052315A1
WO2021052315A1 PCT/CN2020/115286 CN2020115286W WO2021052315A1 WO 2021052315 A1 WO2021052315 A1 WO 2021052315A1 CN 2020115286 W CN2020115286 W CN 2020115286W WO 2021052315 A1 WO2021052315 A1 WO 2021052315A1
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strip
hot
steel
rolled steel
30crmo
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PCT/CN2020/115286
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English (en)
Chinese (zh)
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吴建春
方园
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宝山钢铁股份有限公司
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Priority claimed from CN201910888783.4A external-priority patent/CN112522579B/zh
Priority claimed from CN201910889384.XA external-priority patent/CN112522593B/zh
Application filed by 宝山钢铁股份有限公司 filed Critical 宝山钢铁股份有限公司
Priority to DE112020004461.0T priority Critical patent/DE112020004461T5/de
Publication of WO2021052315A1 publication Critical patent/WO2021052315A1/fr

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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
    • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • B22D11/0622—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by two casting wheels
    • 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
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/1206—Accessories for subsequent treating or working cast stock in situ for plastic shaping of strands
    • 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
    • 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
    • C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
    • 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
    • C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
    • C21D1/613—Gases; Liquefied or solidified normally gaseous material
    • 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
    • C21D8/021—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular fabrication or treatment of ingot or slab
    • 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
    • C21D8/021—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular fabrication or treatment of ingot or slab
    • C21D8/0215—Rapid solidification; Thin strip casting
    • 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
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • 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
    • C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
    • 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
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
    • 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
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • 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
    • C21D2211/009—Pearlite
    • 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

Definitions

  • the invention belongs to a continuous casting process, and specifically relates to a 30CrMo hot-rolled steel plate/strip and a production method thereof.
  • tin (Sn) and copper (Cu) are typical residual elements or harmful elements in steel. It is very difficult and very expensive to fully remove Sn and Cu during the steelmaking process. Once the steel contains Sn , Cu, basically can not be completely eliminated, only by diluting molten steel to reduce the content of Sn, Cu, these all cause the increase in the smelting cost of steel products.
  • Traditional thin strip steel is mostly produced by continuous rolling of cast billets with a thickness of 200-250mm through multiple passes.
  • the traditional hot rolling process is: continuous casting + billet reheating and heat preservation + rough rolling + finishing rolling + cooling + Coiling, that is, firstly obtain a cast slab with a thickness of about 200mm through continuous casting. After reheating and holding the cast slab, rough rolling and finishing rolling are performed to obtain a steel strip with a thickness generally greater than 2mm, and finally the steel strip is processed Laminar cooling and coiling complete the entire hot rolling production process. If the steel strip with a thickness of less than 2.0mm (inclusive) is to be produced, it is relatively difficult, and the hot-rolled steel strip is usually subjected to subsequent cold rolling and annealing to complete. In addition, the long process flow, high energy consumption, many units and equipment, and high capital construction costs result in high production costs.
  • the thin slab continuous casting and rolling process is: continuous casting + slab heat preservation and soaking + hot continuous rolling + cooling + coiling.
  • the main difference between this process and the traditional process is that the thickness of the cast slab in the thin slab process is greatly reduced to 50-120mm. Because the cast slab is thin, the cast slab only needs to undergo 1 to 2 passes of rough rolling (the thickness of the cast slab is 70-90mm When the thickness of the cast slab is 50mm, the thickness of the continuous casting slab in the traditional process must be repeatedly rolled to reduce the thickness to the required specifications before the finish rolling; and the thin slab casting process is not necessary to go through rough rolling (when the thickness of the cast slab is 50mm).
  • the billet directly enters the soaking furnace for soaking and heat preservation, or a small amount of temperature compensation, so the thin slab process greatly shortens the process flow, reduces energy consumption, reduces investment, and reduces production costs.
  • the faster cooling rate of thin slab continuous casting and rolling the strength of the steel will increase and the yield ratio will increase, thereby increasing the rolling load, so that the thickness specification of the hot-rolled product can be economically produced and the thickness specification is not too thin, generally ⁇ 1.5mm, see Chinese patent application numbers CN 2 00610123458.1, CN 2 00610035800.2 and CN 2 00710031548.2.
  • ESP all-headless thin slab continuous casting and rolling process
  • the flame cutting of slab and the heating furnace for heat preservation and soaking and slab transition are eliminated, and the length of the entire production line is greatly shortened to about 190 meters.
  • the thickness of the slab casted by the continuous casting machine is 90-110mm, and the width is 1100-1600mm.
  • the continuous casting slab passes through a section of induction heating roller table to keep the slab warm and soak, and then enters the rough rolling one by one. , Finish rolling, layer cooling, and coiling processes to obtain hot-rolled plates.
  • this process can obtain the thinnest hot-rolled sheet with a thickness of 0.8mm, which expands the specification range of the hot-rolled sheet.
  • its single production line output can reach 2.2 million tons/year.
  • the process has been rapidly developed and promoted.
  • the shorter process flow than thin slab continuous casting and rolling is the thin strip continuous casting and rolling process.
  • the thin strip continuous casting technology is a cutting-edge technology in the field of metallurgy and materials research. Its appearance has brought a revolution to the steel industry. It changes the production process of steel strip in the traditional metallurgical industry, integrating continuous casting, rolling, and even heat treatment into one, so that the produced thin strip can be formed into thin steel strip at one time after one online hot rolling.
  • the "one-fire material" of thin steel strip products greatly simplifies the production process and shortens the production cycle. The length of the process line is only about 50m; the equipment investment is also reduced, and the product cost is significantly reduced. It is a low-carbon and environmentally friendly hot rolling Thin strip production process.
  • the twin-roll thin strip continuous casting process is a main form of the thin strip continuous casting process, and it is also the world's only industrialized thin strip continuous casting process.
  • the typical process flow of twin-roll thin strip continuous casting is shown in Figure 1.
  • the molten steel in the ladle 1 is directly poured into one by two through the ladle nozzle 2, the tundish 3, the immersion nozzle 4 and the distributor 5
  • the molten steel solidifies on the rotating circumferential surfaces of the crystallizing rollers 8a, 8b to form a solidified shell and gradually grow, and then the two A 2-5mm thick cast strip 11 is formed at the smallest gap (nip point) of the crystallizing roller.
  • the cast strip is guided to the pinch roll 12 via the guide plate 9 and fed into the rolling mill 13 to be rolled into a thin strip of 0.7-2.5mm, and then passed through the cooling device 14 is cooled, after being cut by the flying shear device 16, it is finally sent to the coiler 19 to be wound into a roll.
  • 30CrMo alloy steel has high strength and toughness, good hardenability, and has excellent comprehensive mechanical properties after quenching low temperature tempering and quenching high temperature tempering. After quenching and tempering, this steel has high strength below 550°C, good low-temperature toughness, no temper brittleness, and good weldability, machinability and machinability.
  • 30CrMo is widely used in machinery manufacturing, petrochemical industry, boiler manufacturing and saw blade die industry, etc. According to market statistics, the market consumption of thin 30CrMo is 100,000 to 150,000 tons/year, and the market usage and future potential are huge.
  • the reasonable combination of Cr and Mo elements in 30CrMo steel enables the steel to have good room temperature and high temperature properties. It can obtain compact structure and high strength without significantly reducing plasticity. At the same time, it also improves the hardenability of steel and increases tempering. Time stability, eliminating temper brittleness and the tendency of grain growth at high temperature.
  • the mainstream production process of 30CrMo steel plate/strip is: converter / electric furnace-refining-conventional thick slab continuous casting-walking heating furnace-rough rolling-multi-stand finishing rolling-laminar cooling-coiling.
  • the 30CrMo steel plate/strip produced by this traditional production process mainly has the following problems: (1) Composition segregation and internal looseness: Due to the high alloy content in the steel, the drawing speed during continuous casting of thick slabs is low, and the molten steel is solidified. Slowly, it is easy to cause serious component segregation and internal looseness in the slab, which will eventually lead to uneven product quality and performance; (2) Surface decarburization: Because of the high carbon content in steel, a walking heating furnace is used to heat the slab.
  • the thin gauge 30CrMo hot-rolled steel sheet/strip has a characteristic thickness of 1.5-3.0mm. Due to the thin thickness of the product, it will be more difficult to use the above-mentioned traditional continuous casting + hot rolling production line for production. Even if thin slab continuous casting and rolling production is adopted, since the thickness of the slab must reach 70-120mm, there is no order of magnitude and essential difference in the size and thickness of the slab from the traditional thick slab continuous casting (slab thickness 200-250mm) Therefore, it is impossible to fundamentally solve the problem of element segregation.
  • the continuous casting slab still has to pass through a tunnel heating furnace or an electromagnetic induction heating section, and the problem of decarburization on the surface of the material cannot be completely eliminated; in addition, thinner specifications are rolled. Will cause the roll consumption of the roll to be larger. Therefore, the traditional thick slab continuous casting or thin slab continuous casting production process cannot completely solve the problems in the production of 30CrMo steel, and the production cost of the thin-gauge 30CrMo hot-rolled steel plate/strip will also be very high.
  • the products produced by thin strip continuous casting will generally have problems such as uneven structure, low elongation, and uneven performance. This is due to the austenite grains in the cast strip. Obvious inhomogeneity will result in uneven structure of the final product obtained after austenite transformation, resulting in unstable product performance, especially elongation and formability; at the same time, thin strip continuous casting is in the production of higher carbon
  • the molten steel is too late to feed, and it is easy to cause internal shrinkage/shrinkage cavities near the center area of the cast strip.
  • the purpose of the present invention is to provide a 30CrMo hot-rolled steel sheet/strip and its production method.
  • N element By adding an appropriate amount of N element, combined with a reasonable online hot rolling process and cooling measures after rolling, the uniformity of the structure is effectively improved, and the internal shrinkage and shrinkage are solved. Hole problem, improve product quality and performance, and realize the "single-fire material" of thin-gauge 30CrMo hot-rolled steel plate/strip.
  • the thin-gauge 30CrMo hot-rolled steel plate/strip produced by the invention is an ideal material for the thin-gauge steel in the field of machinery manufacturing, petrochemical industry, boiler manufacturing industry and saw blade and die industry.
  • the invention makes full use of the residual Sn, Cu and other elements in the scrap steel to smelt molten steel, and selectively adds Mo, Cr and other microalloy elements and B, N and other elements to the steel; during the smelting process, the alkalinity of the slag is controlled, The type and melting point of the inclusions in the steel, the free oxygen content in the molten steel, and the acid-soluble aluminum Als content; then double-roll thin strip continuous casting is carried out to cast a 2.0-5.0mm thick casting strip, and the casting strip directly enters a crystal roll after it exits the crystallizing roller.
  • the strip steel In the lower airtight chamber with non-oxidizing atmosphere, and enter the online rolling mill under airtight conditions to hot-roll the strip steel to 1.5-3.0mm thickness; after rolling, the strip steel is cooled by the gas atomization cooling method, and the gas mist
  • the cooling method can effectively reduce the thickness of the oxide scale on the surface of the strip, improve the uniformity of the strip temperature, and improve the uniformity and surface quality of the strip.
  • the thin-gauge 30CrMo hot-rolled steel plate/strip produced by the method of the present invention has uniform structure and performance, no internal shrinkage/shrinkage, few decarburization layers, good hardenability, good machinability and workability; the present invention
  • the manufacturing method realizes the "one-fire material" of the thin-gauge 30CrMo hot-rolled steel plate/strip, the production efficiency is greatly improved, and the production cost is greatly reduced. It is a low-carbon, green and environmentally friendly product.
  • the 30CrMo hot-rolled steel sheet/strip of the present invention has a composition weight percentage of: C: 0.24-0.34%, Si: 0.1-0.5%, Mn: 0.6-1.5%, P ⁇ 0.03%, S ⁇ 0.007 %, Cr: 0.80-1.50%, Mo: 0.10-0.30%, N: 0.004-0.010%, Als: ⁇ 0.001%, optional B: 0.001-0.006%, total oxygen [O] T : 0.007-0.020% ;
  • the balance is Fe and unavoidable impurities, and at the same time meet:
  • the microstructure of the 30CrMo hot-rolled steel sheet/strip of the present invention is acicular ferrite (AF) + massive ferrite (PF) + pearlite (P), wherein the proportion of AF: 60-80%, The proportion of PF: 10-25%, the proportion of P: 5-20%.
  • AF acicular ferrite
  • PF massive ferrite
  • P pearlite
  • the tensile strength of the hot-rolled steel sheet/strip of the present invention is less than or equal to 900 MPa, and the hardness is less than or equal to HRC 25.
  • the 30CrMo hot-rolled steel sheet/strip of the present invention has a tensile strength of 780-900 MPa, a yield strength of 590-750 MPa, an elongation of 11-23%, and a yield ratio of 0.75-0.83.
  • the 30CrMo hot-rolled steel sheet/strip of the present invention has a composition weight percentage of: C: 0.24-0.34%, Si: 0.1-0.5%, Mn: 0.6-1.5%, P ⁇ 0.03%, S ⁇ 0.007%, Cr: 0.80-1.50%, Mo: 0.10-0.30%, N: 0.004-0.010%, Als: ⁇ 0.001%, B: 0.001-0.006%, total oxygen [O] T : 0.007-0.020%
  • the balance is Fe and unavoidable impurities, and at the same time meets: Containing one or two elements of Cu: 0.10-0.60% and Sn: 0.005-0.04%, Mn/S ⁇ 250.
  • the microstructure of the 30CrMo hot-rolled steel sheet/strip is acicular ferrite (AF) + massive ferrite (PF) + pearlite (P), wherein the proportion of AF: 60-80%, PF The ratio of P: 10-25%, the ratio of P: 5-20%.
  • AF acicular ferrite
  • PF massive ferrite
  • P pearlite
  • the 30CrMo hot-rolled steel sheet/strip of the present invention has a composition weight percentage of: C: 0.24-0.34%, Si: 0.1-0.5%, Mn: 0.6-1.5%, P ⁇ 0.03%, S ⁇ 0.007%, Cr: 0.80-1.50%, Mo: 0.10-0.30%, N: 0.004-0.010%, Als: ⁇ 0.001%, total oxygen [O] T : 0.007-0.020%; the balance is Fe and non Avoid impurities, and meet at the same time: contain one or two elements of Cu: 0.10-0.60% and Sn: 0.005-0.04%, and Mn/S ⁇ 250.
  • Mn/S Preferably, in the 30CrMo hot-rolled steel sheet/strip of the present invention, Mn/S>250.
  • C is the most economical and basic strengthening element in steel.
  • the strength of the steel is improved by solid solution strengthening and precipitation strengthening to ensure quenching hardness and quenching.
  • C is an essential element for the precipitation of cementite during austenite transformation. Therefore, the level of C content determines the strength level of steel to a large extent, that is, a higher C content corresponds to a higher strength level.
  • the C content should not be too high, too high will result in high deformation resistance during rolling, lower toughness after quenching and tempering heat treatment, and also affect welding performance.
  • Si plays a solid solution strengthening effect in steel, and the addition of Si to steel can help deoxidize to form silicate, which helps to improve cutting performance and at the same time improve the purity of steel, but excessive Si content will affect weldability And increase the brittleness of steel. Therefore, the range of Si content used in the present invention is 0.1-0.5%.
  • Mn is one of the cheapest alloying elements. It can improve the hardenability and quenching hardness of steel. It has a considerable solid solubility in steel. It can improve the strength of steel through solid solution strengthening, and at the same time, it can improve the plasticity of steel. There is basically no damage to toughness. It is the most important strengthening element to increase the strength of steel. When combined with Si, it can also play a role in deoxidizing steel. However, if the Mn content is too high, the thermal stress and structural stress of the cast strip will increase, and the strip will be easily broken. Therefore, the range of Mn content used in the present invention is 0.6-1.5%.
  • P High content of P is easy to segregate in grain boundaries, increase the cold brittleness of steel, deteriorate welding performance, reduce plasticity, and deteriorate cold bending performance.
  • the solidification and cooling rate of the cast strip is extremely fast, which can effectively inhibit the segregation of P, thereby effectively avoiding the disadvantages of P and giving full play to the advantages of P. Therefore, in the present invention, a higher P content than the traditional production process is adopted, the P element content is appropriately relaxed, and the dephosphorization process is eliminated in the steelmaking process. In actual operation, there is no need to deliberately perform the dephosphorization process, and no additional process is required. Add phosphorus, the range of P content is ⁇ 0.03%.
  • S Under normal circumstances, S is a harmful element in steel, causing steel to produce hot brittleness, reducing the ductility and toughness of steel, and causing cracks during rolling. S also reduces welding performance and corrosion resistance. Therefore, in the present invention, S is controlled as an impurity element, and its content range is ⁇ 0.007%; in some embodiments, the S content is ⁇ 0.006%. And, Mn/S ⁇ 250. In some embodiments, Mn/S>250.
  • the N element can improve the strength of steel through interstitial solid solution.
  • the present invention uses the effect of N and B in the steel to generate the precipitated phase of BN, which requires a certain amount of N in the steel.
  • an appropriate amount of N can promote the precipitation of carbonitrides during the quenching and tempering heat treatment process, and improve the red hardness of the steel during cutting and machining; but too high N content will damage the toughness of the steel and increase the brittleness of the cast strip. Reduce manufacturability. Therefore, the range of N content used in the present invention is 0.004-0.010%.
  • Cr not only is an element that improves the hardenability of steel, it can also effectively improve the high-temperature oxidation resistance and creep resistance of steel. Adding Cr to thin-gauge 30CrMo hot-rolled steel is used to improve the hardenability of steel. , High temperature strength and creep strength, and secondly, it also has secondary hardening effect, which can improve the hardness and wear resistance of steel without making the steel brittle; the combination of Cr and Cu in scrap steel can also improve the corrosion resistance of steel. . However, if its content is too high, it will result in high deformation resistance during rolling, and reduced toughness after quenching and tempering heat treatment, which will affect the cutting process of users. In the present invention, the content of Cr is limited to 0.80-1.50%.
  • Mo can refine grains and improve strength and toughness. Part of Mo is solid-dissolved in ferrite to strengthen the ferrite matrix, and the other part is dispersed in the steel as carbides. Therefore, the Mo-containing steel has both solid solution strengthening and carbide dispersion strengthening. Because Mo diffuses slowly in ferrite at high temperatures, it can also significantly improve the high-temperature strength and tempering stability of steel. However, excessively high Mo will significantly increase the raw material smelting cost of steel. Therefore, in the present invention, the Mo content is limited to 0.10-0.30%.
  • Cu It mainly plays a solid solution and precipitation strengthening effect in steel.
  • the combined effect of Cu and Cr can also improve the corrosion resistance of 30CrMo steel, making the steel of the present invention suitable for some corrosive occasions, and weather resistance is not easy to rust.
  • the present invention uses scrap steel as a raw material, and there is no need to add Cu during smelting. Since Cu is an easily segregated element, the Cu content is generally strictly controlled in the traditional process. Using the rapid solidification effect of thin strip continuous casting, the present invention increases the upper limit of Cu to 0.60%. The increase of Cu content can make full use of scrap steel in a certain sense.
  • Sn It is also one of the main residual elements in scrap steel. It is recognized as a harmful element in steel. Because Sn is an element that is easy to segregate, a small amount of Sn will be enriched at the grain boundary, resulting in cracks and other defects. The content of Sn element in the process is strictly controlled. Due to the characteristics of rapid solidification of thin strip continuous casting, the segregation of elements in the dendrites is greatly reduced, which can greatly increase the amount of solid solution of the elements. Therefore, under the conditions of the thin strip continuous casting process, the range of Sn elements can be expanded, so it can greatly Reduce steelmaking costs.
  • Figure 2 is the relationship between the Sn element and the average heat flux. It can be seen from Fig.
  • FIG. 3 shows the relationship between Sn content and surface roughness. Because the cracks on the surface of the cast strip are usually produced at the uneven wrinkles on the surface of the cast strip, the surface roughness is used to characterize the occurrence of surface cracks. If the roughness is large, the probability of occurrence of cracks is high. It can be seen from Fig. 3 that the increase of Sn content does not adversely affect the surface quality of the cast strip under the conditions of rapid solidification. From the results of Fig. 2 and Fig. 3, it can be seen that Sn has no adverse effect on the solidification and surface quality of the cast strip. Therefore, in the present invention, the requirements for the content of Sn can be further relaxed. When Sn is contained, the content of Sn is designed to be in the range of 0.005-0.04%.
  • B The significant effect of B in steel is: a very small amount of boron can double the hardenability of steel, and B can preferentially precipitate coarse BN particles in high-temperature austenite, thereby inhibiting the precipitation of fine AlN and weakening the fineness
  • the pinning effect of AlN on grain boundaries improves the growth ability of grains, thereby coarsening and homogenizing austenite grains, which is beneficial to improve the machinability of steel coil products, and is beneficial to subsequent users for cutting or machining;
  • B The combination with N can effectively prevent the appearance of the low melting point phase B 2 O 3 of the grain boundary, thereby avoiding thermal embrittlement.
  • B is a lively and easily segregated element, which is easy to segregate in the grain boundary.
  • the B content is generally controlled very strictly, generally around 0.001-0.003%; while in the thin strip continuous casting process, solidification and cooling The speed is faster, which can effectively inhibit the segregation of B and solid-solve more B content, so the B content can be appropriately relaxed; it can also be controlled by a reasonable process to generate coarse BN particles, inhibit the precipitation of fine AlN, and achieve nitrogen fixation effect.
  • Studies have also shown that when B is added in combination with Mo, it will get better results, will reduce the segregation tendency of C atoms, and avoid the precipitation of grain boundary Fe23(C,B)6, so you can add more B. Therefore, in some embodiments of the present invention, a higher B content than the traditional process is used, and the range is 0.001-0.006%.
  • the production method of 30CrMo hot-rolled steel sheet/strip according to the present invention includes the following steps:
  • the MnO/SiO 2 (mass ratio) in the SiO 2 -Al 2 O 3 ternary inclusions is controlled at 0.5-2, preferably 1 to 1.8;
  • the free oxygen [O] Free content in the molten steel is: 0.0005 to 0.005%; Mn/S>250;
  • the continuous casting adopts double-roll thin strip continuous casting to form a 2.0-5.0mm thick cast strip (preferably, the thickness of the cast strip is formed at the smallest gap between the two crystallizing rolls; the diameter of the crystallizing roll is 500-1500mm, and the preferred roll diameter is 800mm, the inside of the crystallizing roll is cooled by water; the casting speed of the casting machine is 40-100m/min; the ladle opening temperature is controlled at 1580-1610°C; the continuous casting cloth flow adopts a two-stage molten steel distribution flow system, namely tundish + cloth flow Device.
  • the temperature of the casting belt is 1360-1430°C, and it enters the lower closed chamber directly.
  • the lower closed chamber is filled with non-oxidizing gas.
  • the oxygen concentration in the lower closed chamber is controlled at ⁇ 5%.
  • the casting belt at the exit of the lower closed chamber The temperature is between 1150-1280°C;
  • the cast strip is sent to the rolling mill via pinch rolls in the lower enclosed chamber and rolled into strip steel with a thickness of 1.5-3.0mm.
  • the rolling temperature is 1100-1250°C and the hot rolling reduction rate is 10-50%.
  • hot rolling The reduction rate is 30-50%;
  • Cooling the strip steel after online hot rolling the cooling adopts gas atomization cooling method, and the cooling rate of gas atomization cooling is 10-100°C/s;
  • the cooled hot-rolled steel strip is coiled into a coil, and the coiling temperature of the hot-rolled steel strip is controlled to be 700-760°C.
  • step 6 tempering heat treatment: oil quenching at 840-880°C, tempering at 400-440°C.
  • tempering heat treatment oil quenching at 840-880°C, tempering at 400-440°C.
  • the user performs cutting and machining according to the size of the final product, and finally performs the quenching and tempering heat treatment.
  • the quenching and tempering heat treatment can ensure that the material obtains a uniform sorbite structure and hardness distribution, and can reduce the deformation of the sheet.
  • the required material hardness can be obtained after quenching and tempering heat treatment: HRC35 ⁇ 2.
  • the smelting raw material can be made of 100% scrap steel without pre-screening, and the molten steel smelting adopts electric furnace steelmaking, which greatly reduces the raw material cost; or, the smelting adopts converter steelmaking, and the scrap steel accounts for more than 20% of the smelting raw material It is added to the converter without pre-screening, which maximizes the scrap ratio of the converter and greatly reduces the smelting cost and energy consumption; then enters the LF furnace, VD/VOD furnace or RH furnace for refining.
  • the non-oxidizing gas includes inert gas, N 2 , CO 2 gas obtained by sublimation of dry ice, and a mixed gas of N 2 and H 2.
  • the gas-water ratio of the gas atomization cooling is 15:1-10:1, the air pressure is 0.5-0.8 MPa, and the water pressure is 1.0-1.5 MPa.
  • air-water ratio refers to the flow ratio of compressed air and water, and the unit of flow is m 3 /h.
  • the coiling adopts the form of a double coiler, or adopts the form of a Carrousel coiling.
  • step 5 after the cooled hot-rolled steel strip is cut by a cutting head to remove the poor quality head, it is directly coiled into a coil, and the coiling temperature of the hot-rolled steel strip is controlled to be 700-760°C.
  • MnO-SiO 2 -Al 2 O 3 ternary inclusions In order to improve the castability of thin strip continuous casting molten steel, it is necessary to obtain low melting point MnO-SiO 2 -Al 2 O 3 ternary inclusions, as shown in the shaded area in Figure 4, MnO-SiO 2 -Al 2 O 3 ternary inclusions
  • the MnO/SiO 2 in the composition is controlled to be 0.5-2, preferably 1 to 1.8.
  • oxygen (O) in the steel is an essential element for the formation of oxidized inclusions.
  • the present invention requires the formation of low melting point ternary inclusions of MnO-SiO 2 -Al 2 O 3 ,
  • the required free oxygen [O] Free range in molten steel is: 0.0005-0.005%.
  • the diameter of the crystallization roller of the present invention is between 500-1500mm, preferably 800mm; the inside of the crystallization roller is cooled by water.
  • the casting speed of the casting machine ranges from 40-100m/min.
  • the liquidus temperature of the 30CrMo steel grade designed by the invention is about 1500°C, and the ladle opening temperature range is 1580-1610°C.
  • the temperature of the casting belt is 1360-1430°C, and it enters the lower closed chamber directly.
  • the lower closed chamber is protected by non-oxidizing gas to protect the casting belt from oxidation. It can be N 2 , Ar can also be other non-oxidizing gases, such as CO 2 gas obtained by sublimation of dry ice, a mixed gas of N 2 and H 2 , etc.
  • the oxygen concentration in the lower enclosed chamber is controlled to ⁇ 5%.
  • the lower airtight chamber protects the cast strip from oxidation to the entrance of the rolling mill 13.
  • the temperature of the casting strip at the outlet of the lower closed chamber is 1150-1280°C.
  • thermodynamic equations of boron and nitrogen, aluminum and nitrogen in ⁇ -Fe in steel are as follows:
  • the initial precipitation temperature of BN in steel is about 1280°C, and the precipitation of BN tends to be balanced at 980°C, while the precipitation of AlN has just begun (the precipitation temperature of AlN is about 980°C).
  • the precipitation of BN has priority over AlN.
  • the invention completes the combination of B and N in the lower closed chamber to generate coarse BN particles, thereby inhibiting the precipitation of fine AlN, weakening the pinning effect of fine AlN on grain boundaries, improving the growth ability of grains, and thereby coarsening austenite
  • the grains make the austenite grains more uniform, which is beneficial to improve the cutting performance and machinability of the material; in addition, the combination of B and N can effectively prevent the appearance of the low melting point phase B 2 O 3 at the grain boundary.
  • the cast strip is sent to the rolling mill via pinch rolls in the lower enclosed chamber and rolled into a thin strip with a thickness of 1.5-3.0mm.
  • the rolling temperature is 1100-1250°C, and a higher rolling temperature can effectively solve the problem of edge cracks that are easy to occur in traditional processes.
  • the hot rolling reduction rate is 10-50%.
  • the hot rolling reduction rate is in the range of 30-50%.
  • the larger reduction rate of a single stand can completely solve the problem near the center area of the cast strip caused by the higher C content. Internal shrinkage/shrinkage problem.
  • the cooling method adopts gas atomization cooling method.
  • the gas atomization cooling method can effectively reduce the thickness of the oxide scale on the surface of the strip, improve the temperature uniformity of the strip, and improve the performance and surface of the strip. quality.
  • the gas-water ratio of gas atomization cooling is 15:1 ⁇ 10:1, the air pressure is 0.5 ⁇ 0.8MPa, and the water pressure is 1.0 ⁇ 1.5MPa.
  • high-pressure water mist is sprayed on the surface of the steel strip. On the one hand, it can reduce the temperature of the steel strip. On the other hand, the water mist will form a dense gas film covering the surface of the steel strip, which can prevent the strip from being oxidized.
  • This cooling method can avoid the problems caused by traditional spraying or laminar cooling, make the surface temperature of the strip drop uniformly, improve the uniformity of the strip temperature, and achieve the effect of homogenizing the internal microstructure; at the same time, the uniform cooling can improve the strip The shape quality and performance stability of the steel; effectively reduce the thickness of the oxide scale on the surface of the strip.
  • the cooling rate of gas atomization cooling is in the range of 10-100°C/s.
  • the cooled hot-rolled steel strip is cut by the cutting head to remove the poor quality head, and then directly coiled into a coil.
  • Control the coiling temperature of the hot-rolled strip from 700 to 760°C.
  • the high coiling temperature can ensure that the steel of the present invention obtains the lowest possible tensile strength (less than 900MPa) and hardness (under HRC25), so that it can be coiled smoothly; for downstream manufacturing users, it is also easier to perform various cutting and Machining.
  • the coiling adopts the form of double coiling machine, and can also adopt the form of Carrosel coiling to ensure the continuous production of strip steel.
  • the coiling adopts the Carrousel coiling form, which can make the length of the production line shorter and more compact.
  • the most obvious feature of the present invention which is different from the existing thin strip continuous casting technology is the roll diameter of the crystallizing roll and the corresponding flow distribution method.
  • the technical feature of EUROSTRIP is ⁇ 1500mm large diameter crystallizing roller, large crystallizing roller, large molten steel capacity in molten pool, easy flow distribution, high cost of crystallizing roller manufacturing and operation and maintenance.
  • the technical feature of CASTRIP is the ⁇ 500mm small diameter crystallizing roller, the crystallizing roller is small, the molten steel volume is small, and the flow distribution is very difficult, but the cost of manufacturing and operation and maintenance of the casting machine is low.
  • CASTRIP adopts a three-stage molten steel distribution flow system (tundish + transition bag + flow distributor).
  • the use of a three-stage flow distribution system directly leads to an increase in the cost of refractory materials; more importantly, the three-stage flow distribution system makes the path of molten steel flow longer and the temperature drop of molten steel is also greater.
  • the tapping temperature needs to be greatly increased. The increase in the tapping temperature will cause problems such as increased steelmaking costs, increased energy consumption, and shortened life of refractory materials.
  • the crystal roll with a diameter of 500-1500mm, preferably 800mm adopts a two-stage molten steel distribution system (tundish + flow distributor).
  • the molten steel flowing out of the distributor forms different distribution patterns along the roller surface and the two end surfaces, and flows in two paths without interfering with each other. Due to the use of a two-stage flow distribution system, compared with a three-stage flow system, the cost of refractory materials is greatly reduced; the shortening of the molten steel flow path reduces the temperature drop of the molten steel, which can lower the tapping temperature, compared with the three-stage flow system , The tapping temperature can be reduced by 30-50°C.
  • the lowering of the tapping temperature can effectively reduce the cost of steelmaking, save energy and extend the life of refractory materials.
  • the invention is matched with a crystallizing roller with a roller diameter of ⁇ 800mm and adopts a two-stage molten steel distribution system, which not only realizes the requirement of stable molten steel distribution, but also realizes the goals of simple structure, convenient operation and low processing cost.
  • Cia Patent Publication No. CN101773929B discloses a method for producing 30CrMo hot-rolled steel plate.
  • the method is based on the thin slab continuous casting and rolling process, which mainly includes: smelting, refining, thin slab continuous casting, soaking, high-pressure water descaling, hot continuous Rolling, cooling, coiling and other steps.
  • Its composition is C: 0.26-0.34%, Si: 0.17-0.37%, Mn: 0.40-0.70%, P: ⁇ 0.035%, S ⁇ 0.035%, Cr: 0.80-1.10, Mo: 0.15-0.25%, the rest is Fe and unavoidable impurities.
  • the 30CrMo hot-rolled steel plate produced by this patent has the characteristics of uniform structure and performance, high thermal stability and high strength, and its quality has been significantly improved.
  • the essential difference between this patent and the 30CrMo steel and production method proposed by the present invention is that the production process used is different.
  • the present invention adopts the twin-roll thin strip continuous casting process, and the designed composition is also different, so that no segregation and no surface can be obtained. Decarburized layer, products with better quality and performance.
  • Chinese Patent Publication No. CN107419192A discloses a 30CrMo steel strip and its production method.
  • the invention is also based on the thin slab continuous casting and rolling process, which mainly includes: converter smelting, LF refining, thin slab continuous casting, heating, hot rolling and coiling. Take the process. Its composition is C: 0.26-0.34%, Si: 0.17-0.30%, Mn: 0.40-0.70%, P: ⁇ 0.025%, S ⁇ 0.025%, Als ⁇ 0.010%, Cr: 0.80-1.10%, Mo: 0.15 -0.25%, Ni ⁇ 0.30%, Cu ⁇ 0.30%, the balance is Fe and unavoidable impurities.
  • the invention eliminates the central segregation and central shrinkage of the continuous casting billet, reduces surface decarburization, and can produce 2.5-4.0mm thick hot-rolled thin gauge steel strip, realizing the low cost of 30CrMo steel produce.
  • the patent and the 30CrMo steel and production method proposed by the present invention are also essentially different in the production process.
  • the present invention adopts the twin-roll thin strip continuous casting process, which simplifies the production process, and the design composition is different, which can be obtained A product with no segregation, no surface decarburization layer, and better quality performance.
  • Chinese Patent Publication No. CN100366779C discloses a stone cutting saw blade steel and its manufacturing method. Its chemical composition weight percentage is C 0.45-0.60%, Si 0.1-0.6%, Mn 1.3-1.8%, P ⁇ 0.02%, S ⁇ 0.01%, V 0.05-0.20%, Cr 0.15-0.30%, N 0.005-0.020%, Ca 0-0.0050%, Al 0.005-0.040%, the rest are Fe and unavoidable impurities.
  • the method includes: smelting, casting, and continuous casting billets adopt hot charging and hot delivery processes to ensure that the temperature of the slab before heating is above 300°C, the slab heating temperature is above 1150°C, and the final rolling temperature is controlled to be above 900°C during hot rolling.
  • Air-cooled coiling after rolling, the coiling temperature is above 700°C.
  • the inventive steel has high hardenability, and is particularly suitable for manufacturing saw blades for stone cutting with a diameter of more than 1000 mm.
  • This patent is different from the steel type involved in the present invention.
  • the carbon content of the patent is 0.45-0.60%, and the carbon content of the present invention is 0.24-0.34%. There are essential differences in the production process. The casting process further simplifies the production process.
  • Chinese Patent Publication No. CN102345071B discloses a structural steel 30CrMo plus B steel plate for alloys and its production method.
  • the plate contains the following mass percentages of chemical composition: C: 0.28-0.33%, Si: 0.20-0.35%, Mn: 0.60- 0.80%, P: ⁇ 0.018%, S: ⁇ 0.005%, Cr: 0.90-1.10%, Mo: 0.15-0.25%, Als: 0.20-0.40%, B: 0.0008-0.0015%, the rest is Fe and residual elements.
  • the production methods adopted include: converter steelmaking, LF refining, vacuum refining, pouring, billet/steel heating, rolling, slow cooling, heat treatment, and successfully developed high-strength 30CrMo plus B steel ⁇ 100mm.
  • this invention also adds a trace amount of B, because it uses the most traditional and backward mold casting process, the solidification rate is very slow, B is easy to segregate, and the low melting point B 2 O 3 phase is easy to appear in the grain boundary to cause hot cracks. Therefore, the addition amount of B is very low, only 0.0008-0.0015%, and the effect is very small.
  • the thickness specifications of the produced products are also relatively thick, with thicknesses of 50 mm and 100 mm.
  • the invention adopts an advanced twin-roll thin strip continuous casting process to directly produce a 1.5-3.0mm steel plate/belt.
  • the addition amount of B can reach 0.006%, and the quality performance is more excellent. It has the same composition and production method as the patent. The difference.
  • the present invention uses thin strip continuous casting technology to produce thin gauge 30CrMo hot-rolled steel containing tin (Sn), copper (Cu)/tin (Sn), copper (Cu), nitrogen (N) and optionally boron (B) There is no report so far.
  • Sn tin
  • Cu copper
  • Cu copper
  • N nitrogen
  • B optionally boron
  • the present invention eliminates the need for complex processes such as slab heating and multi-pass repeated hot rolling. Through double-roll thin strip continuous casting + one online hot rolling process, the production process is shorter, the efficiency is higher, and the investment cost of the production line is reduced. The production cost is greatly reduced.
  • the present invention omits many complicated intermediate steps in the traditional production process. Compared with the traditional production process, the energy consumption and CO 2 emission of production are greatly reduced, and it is a green and environmentally friendly product.
  • the present invention adopts thin strip continuous casting process to produce thin gauge 30CrMo hot-rolled steel. Due to the advanced nature of the process, it can completely solve the problems of surface decarburization, element segregation and edge cracking in the traditional process.
  • the speed of continuous casting of thin strip reaches 80-150m/min, the solidification speed of molten steel reaches 10 2 -10 4 °C/s, and the thickness of continuous casting is only 2-5mm.
  • the alloying elements in 30CrMo steel are in a short time ( 0.1-0.2s) It is completely solidified before the segregation occurs. This rapid solidification effect effectively eliminates the problem of element segregation;
  • the continuously cast steel strip quickly enters the lower closed room with a protective atmosphere, and then directly enters the online hot rolling mill for hot rolling.
  • the whole process of protection casting and rolling makes the surface of the strip steel hardly decarburized. ;
  • the thin strip continuous casting and rolling process organically integrates the traditional continuous casting, heating, hot continuous rolling and other independent processes.
  • the production cycle is greatly shortened, the production efficiency is greatly improved, the energy consumption is greatly reduced, and the product quality and performance are greatly improved. .
  • the invention adopts the addition of a trace amount of N element, which can promote the precipitation of carbonitrides during the quenching and tempering heat treatment of the invention steel, effectively improve the red hardness of 30CrMo steel in the cutting and machining process, and is beneficial to prolong the service life of the final product .
  • the present invention makes full use of scrap steel in raw materials without screening, and uses scrap steel containing Cu and Sn, combined with the sub-rapid solidification effect of thin strip continuous casting, to play the role of alloying residual elements , Greatly reduce the cost of smelting, "turn harm into profit" for Cu and Sn in steel, realize full utilization of existing scrap steel or low-quality inferior mineral resources (high tin ore, high copper ore), and promote the recycling of scrap steel Utilize, reduce production costs, and realize the sustainable development of the steel industry.
  • the smelting of the invention adopts electric furnace steelmaking, and the raw materials for smelting can realize 100% scrap steel smelting in a true sense without pre-screening, which greatly reduces the cost of raw materials; if the smelting adopts converter steelmaking, the scrap steel accounts for more than 20% of the smelting raw materials.
  • the converter is added without pre-screening, which maximizes the scrap ratio of the converter and greatly reduces the smelting cost and energy consumption.
  • the present invention adopts the strip steel gas atomization cooling method after rolling, which can avoid the problems caused by traditional spraying or laminar cooling, so that the surface temperature of the strip can be uniformly reduced, and the uniformity of the strip temperature can be improved, thereby achieving uniform internal microcosmic
  • uniform cooling can improve the shape quality and performance stability of the strip; effectively reduce the thickness of the oxide scale on the surface of the strip.
  • the precipitation of alloying elements occurs during the cooling process of the traditional slab, and the utilization rate of the alloying elements is often reduced due to insufficient re-dissolution of the alloying elements when the slab is reheated.
  • the high-temperature cast strip is directly hot-rolled, and the added alloy elements mainly exist in a solid solution state, which can improve the alloy utilization rate.
  • the present invention uses a hot-rolled steel strip Carrousel coiler, which effectively shortens the length of the production line; at the same time, the co-coiling can greatly improve the control accuracy of the coiling temperature and improve the stability of the product performance.
  • Figure 1 is a schematic diagram of the process layout of the twin-roll thin strip continuous casting process
  • Figure 2 is a schematic diagram of the relationship between Sn content and average heat flux
  • Figure 3 is a schematic diagram of the relationship between the Sn content and the surface roughness of the cast strip
  • Figure 4 is a ternary phase diagram of MnO-SiO 2 -Al 2 O 3 (shaded area: low melting point area);
  • Figure 5 is a schematic diagram of the thermodynamic curves of the precipitation of BN and AlN.
  • the molten steel in accordance with the chemical composition design of the present invention is directly poured in a large ladle 1, through a ladle nozzle 2, a tundish 3, an immersion nozzle 4, and a distributor 5, which is rotated by two relative rotations and can be quickly
  • the molten steel solidifies on the rotating circumferential surfaces of the crystallizing rollers 8a, 8b, and then forms a solidified shell and gradually grows on the two crystallizing rollers.
  • a 2.0-5.0mm thick cast strip 11 is formed; after the cast strip 11 exits the crystallizing rollers 8a, 8b, the temperature of the cast strip is 1360-1430°C, directly enters the lower airtight chamber 10, and is airtight.
  • the chamber 10 is protected by an inert gas to protect the strip steel from oxidation.
  • the atmosphere for the anti-oxidation protection can be N 2 , Ar or other non-oxidizing gases, such as a mixture of N 2 and H 2
  • the oxygen concentration in the lower airtight chamber 10 is controlled to be less than 5%, such as CO 2 gas obtained by sublimation of dry ice and dry ice.
  • the lower airtight chamber 10 protects the cast strip 11 from oxidation to the entrance of the rolling mill 13.
  • the temperature of the cast strip at the outlet of the lower closed chamber 10 is 1150-1280°C; then the cast strip is sent to the hot rolling mill 13 through the swinging guide plate 9, the pinch roll 12, and the roller table 15.
  • the gas atomization rapid cooling device 14 is used to cool the hot rolled strip steel in a gas atomization cooling manner to improve the temperature uniformity of the strip steel.
  • the cutting head falls into the flying shear pit 18 along the flying shear guide plate 17, and the hot-rolled strip after the cutting head enters the Carrousel coiler 19 for coiling. After the steel coil is removed from the coiler, it is naturally cooled to room temperature.
  • the user performs cutting and mechanical processing according to the size of the final product, and finally applies a quenching and tempering heat treatment: 840-880°C oil quenching, 400-440°C tempering, adjustment
  • the hardness of the material obtained after the quality heat treatment is within the range of HRC35 ⁇ 2, which ensures the required hardness distribution of the material, and can reduce the deformation of the sheet, and meets and exceeds the performance requirements of the thin-gauge 30CrMo traditional hot-rolled steel.
  • the chemical composition of the embodiment of the present invention is shown in Table 1, and its composition balance is Fe and other unavoidable impurities.
  • the process parameters are shown in Table 2, and the mechanical properties of the finally obtained hot-rolled strip are shown in Table 3.
  • the present invention utilizes thin strip continuous casting technology and makes full use of scrap steel.
  • the 30CrMo hot-rolled steel plate/strip manufactured according to the steel grade composition design range provided by the present invention has a tensile strength of less than 900MPa and a hardness of less than HRC25. , It can be coiled smoothly, and for downstream manufacturing users, it is easy to carry out various cutting and machining.
  • the thin-gauge 30CrMo hot-rolled steel plate/strip produced by the method of the present invention has uniform structure and performance, no internal shrinkage/shrinkage, less decarburization layer, good hardenability, good machinability and machinability, and is a mechanical It is an ideal material for thin-gauge steel in manufacturing, petrochemical, boiler manufacturing, and saw blade die industry.
  • Table 1 The chemical composition of the example steel (wt.%)
  • Example 1 0.24 0.34 1.45 0.018 0.005 0.0087 0.0093 0.0009 1.25 0.23 0.36
  • Example 2 0.26 0.15 0.95 0.023 0.003 0.0073 0.0110 0.0006 1.13 0.21
  • Example 3 0.28 0.10 1.38 0.005 0.004 0.0066 0.0150 0.0004 1.05 0.19 0.10 0.013
  • Example 4 0.30 0.27 1.20 0.016 0.004 0.0055 0.0130 0.0008 1.14 0.28 0.26 0.040
  • Example 5 0.32 0.48 0.66 0.008 0.002 0.0054 0.0120 0.0007 0.93 0.18 0.48
  • Example 6 0.28 0.46 0.69 0.015 0.002 0.0048 0.0070 0.0008 0.86 0.15 0.55
  • Example 7 0.27 0.19 0.86 0.016 0.003 0.0040 0.0100 0.0005 1.02 0.10 0.12 0.025
  • Example 8 0.26 0.36 1.10 0.027 0.004 0.0100 0.0085 0.0006
  • the chemical composition of the B-containing steel examples of the present invention is shown in Table 3, and the composition balance is Fe and unavoidable impurities.
  • the process parameters are shown in Table 4, and the mechanical properties of the finally obtained hot-rolled strip are shown in Table 5.
  • the 30CrMo hot-rolled steel plate/strip manufactured by the thin strip continuous casting process technology according to the steel grade composition design range provided by the present invention has a tensile strength of less than 900 MPa and a hardness of less than HRC 25, which can be successfully coiled and has a downstream effect. For manufacturing users, it is easy to perform various cutting and machining processes.
  • the user performs cutting and mechanical processing according to the size of the final product, and finally applies a quenching and tempering heat treatment: 840-880°C oil quenching, 400-440°C tempering, adjustment
  • the hardness of the material obtained after the quality heat treatment is within the range of HRC35 ⁇ 2, which ensures the required hardness distribution of the material, and can reduce the deformation of the sheet, and meets and exceeds the performance requirements of the thin-gauge 30CrMo traditional hot-rolled steel.
  • the thin-gauge 30CrMo hot-rolled steel plate/strip produced by the method of the present invention has uniform structure and performance, no internal shrinkage/shrinkage, less decarburization layer, good hardenability, good machinability and machinability, and is a mechanical It is an ideal material for thin-gauge steel in manufacturing, petrochemical, boiler manufacturing, and saw blade die industry.
  • the invention can also realize the "one-fire material" of the thin-gauge 30CrMo hot-rolled steel plate/strip, the production cost is greatly reduced, and it is a low-carbon, green and environment-friendly product.
  • Example C Si Mn P S N O Als Cr Mo Cu Sn B 15 0.28 0.25 1.35 0.008 0.005 0.0077 0.0093 0.0009 1.15 0.20 0.37

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Abstract

L'invention concerne une tôle/bande d'acier 30CrMo laminée à chaud et son procédé de production, qui comprend les composants suivants en pourcentage en poids : C : 0,24-0,34 %, Si : 0,1-0,5 %, Mn : 0,6-1,5 %, P≤0,03 %, S≤0,007 %, Cr : 0,80-1,50 %, Mo : 0,10-0,30 % ; N : 0,004-0,010 %, éventuellement B : 0,001-0,006 % : Als<0,001%, oxygène total [O]T: 0,007-0,020 %, un ou deux éléments choisi(s) entre Cu : 0,10-0,60 % et Sn : 0,005-0,04 %, Mn/S≥250, le reste étant du Fe et des impuretés inévitables. Dans la présente invention, des éléments résiduels tels que Sn et Cu d'acier de rebut sont entièrement utilisés pour la fusion, et des éléments tels que Mo, Cr et N sont ajoutés de manière sélective ; l'alcalinité du laitier, le type et le point de fusion d'inclusions dans l'acier, et la teneur en oxygène libre ainsi que la teneur en Als (aluminium soluble dans l'acide) de l'acier fondu sont contrôlés ; une bande coulée est obtenue à l'aide d'un procédé de coulée continue à bande mince entre cylindres, et est ensuite laminée à chaud sur chaîne de production pour former une bande d'acier. La présente invention permet de réaliser un "laminage à chauffage unique" d'une tôle/bande mince d'acier 30CrMo laminée à chaud, d'améliorer considérablement l'efficacité de production et de réduire considérablement les coûts de production.
PCT/CN2020/115286 2019-09-19 2020-09-15 Tôle/bande d'acier 30crmo laminée à chaud et son procédé de production WO2021052315A1 (fr)

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CN201910888783.4A CN112522579B (zh) 2019-09-19 2019-09-19 一种利用废钢的30CrMo热轧钢板/带及其生产方法
CN201910889384.XA CN112522593B (zh) 2019-09-19 2019-09-19 一种薄规格30CrMo热轧钢板/带及其生产方法
CN201910888783.4 2019-09-19

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CN114686753A (zh) * 2022-04-20 2022-07-01 张家港宏昌钢板有限公司 40Mn热轧钢材的生产方法、40Mn热轧钢材及其用途
CN114717481A (zh) * 2022-04-19 2022-07-08 安阳钢铁股份有限公司 一种经济型旋挖钻机套筒用热轧钢带及其生产方法
CN115233081A (zh) * 2022-06-30 2022-10-25 张家港中美超薄带科技有限公司 一种基于双辊铸轧生产30CrMo热轧薄带钢的方法
CN115404332A (zh) * 2022-09-20 2022-11-29 东北大学 一种极薄高强板带钢热处理补温装置及补温方法
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CN116179936A (zh) * 2021-11-26 2023-05-30 江苏新华合金有限公司 一种新型板材及其生产工艺
CN114645190A (zh) * 2022-02-09 2022-06-21 包头钢铁（集团）有限责任公司 一种astm4130钢及其生产方法
CN114717481A (zh) * 2022-04-19 2022-07-08 安阳钢铁股份有限公司 一种经济型旋挖钻机套筒用热轧钢带及其生产方法
CN114717481B (zh) * 2022-04-19 2023-08-04 安阳钢铁股份有限公司 一种经济型旋挖钻机套筒用热轧钢带及其生产方法
CN114686753A (zh) * 2022-04-20 2022-07-01 张家港宏昌钢板有限公司 40Mn热轧钢材的生产方法、40Mn热轧钢材及其用途
CN115233081A (zh) * 2022-06-30 2022-10-25 张家港中美超薄带科技有限公司 一种基于双辊铸轧生产30CrMo热轧薄带钢的方法
CN115233081B (zh) * 2022-06-30 2023-11-10 张家港中美超薄带科技有限公司 一种基于双辊铸轧生产30CrMo热轧薄带钢的方法
CN115404332A (zh) * 2022-09-20 2022-11-29 东北大学 一种极薄高强板带钢热处理补温装置及补温方法
CN115404332B (zh) * 2022-09-20 2024-01-16 东北大学 一种极薄高强板带钢热处理补温装置及补温方法

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