Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • 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
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
• • 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
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
  • C21D8/1233—Cold rolling
• • 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
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
  • C21D8/1255—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest with diffusion of elements, e.g. decarburising, nitriding
• • 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
  • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
• • 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

Definitions

• the present invention relates to the field of black metal ⁇ p ⁇ in and can be used in the production of cold rolled anisotropic electrical steel.
• the technical result of obtaining steel with high magnetic induction is achieved by that. that continuous casting and iodveri steel containing, in mass. % from 2.5 to 4.5 silicon, from 0.015 to 0.075. preferably og 0.025 to 0.050 carbon, 0.03 to 0.40. preferably from 0.05 to 0.20 mar ⁇ anza. less than 0.012. preferably from 0.005 to 0.007 sulfur, from 0.010 to 0.040. preferably 0.02 to 0.035 soluble aluminum, from 0.003 to 0.012. preferably from 0.006 to 0.010 nitrogen, less than 0.005. preferably less than 0.003 piana, iron and the minimum amount of unavoidable impurities remaining.
• High temperature annealing of the slabs is carried out at a temperature of about 1200 to 1320 ° C ⁇ preferably from 1270 to 1310 0 C, after hot rolling the sheet is cooled to a temperature of less than 700 0 C.
• a quick heating of the hot-rolled sheet first to a temperature of from 1000 up to 1,150 ° C, prefer gels io 1060 to 1,130 ° C. followed by cooling, exposure to tcm ->
• the primary recrystallization decarburizing annealing of the cold-rolled sheet is carried out at a temperature of from 800 to 950 0 C for a time of 50 to 350 s in a humid nitrogen-hydrogen atmosphere, at Pn: / Pn: ⁇ > in the range from 0.3 to 0.7.
• continuous nitriding annealing is performed at a temperature of from 850 to 1050 0 C for a time of 15 to 120 s when a gas is fed into the furnace based on a nitrogen-hydrogen mixture containing NH3 in an amount of from 1 to 35 standard liters per kg of sheet, with water vapor content from 0.5 to 100 r / m ⁇
• Secondary crystallization annealing at the final stage of processing is performed at a temperature of from 700 to 1200 0 C for a period of time from 2 to 10 hours, preferably less than 4 hours.
• the continuous casting slabs preferably have the following controlled composition: from 2.5 to 3.5 mass. % silicon, from 0.025 to 0.055 mass. % carbon, or 0.08 to 0.15 wt. % manganese, from 0.025 to 0.035 mass. % soluble aluminum, oi (). (K) 6 to 0.010 mass. % nitrogen, from 0.006 to 0.008 mass. % sulfur and less than 0.004 mass. % of the guitar, the rest is iron and the minimum amount of inevitable impurities, a quick search on a hot-rolled sheet is performed at a temperature of 1060 to 1 130 0 C. The hot-rolled sheet is cooled to a temperature of 900-950 0 C.
• cold rolling is preferably carried out in one step, while maintaining the rolling temperature of at least 180 ° C. for at least one part of the passes: in particular in two intermediate rolling passes, the temperature> pa is from 200 to 220 ° C.
• the decarburization temperature is preferably from 830 up to 880 0 C, while nitriding annealing is performed preferably at 950 0 C or higher; the secondary crystallization annealing at the final stage is carried out at a heating temperature of from 700 to 1200 0 C for a period of time from 2 to 10 hours, preferably less than 4 hours
• the unreleased cooling rate during annealing of a stretched strip in the temperature range from 1000-1 150 to 800-950 0 C, and the cooling rate during rolling, which leads to a spread in the parameters of the structural and text> pnoro state of the strip and can adversely affect the mechanical properties hot rolled metal, breaks during cold rolling and the level of the magnetic properties of the finished steel.
• the high-quality anisotropic electrical steel used in the manufacture of various types of magnetic cores for critical electrical devices has the following basic requirements for magnetic properties: it must have high magnetic permeability and, accordingly, high magnetic induction, and at the same time minimal losses due to magnetization.
• the finished steel must have certain parameters of the grain structure — the perfect texture ⁇ 1 10 ⁇ ⁇ 001> and the optimal grain size, which are formed during secondary crystallization during high-temperature annealing.
• the problem to which the proposed technical solution is directed is to improve the magnetic properties of anisotropic electrical steel.
• the method of production of anisotropic-electrical steel involves the smelting of steel containing, by weight. % oi 2.5 to 3.5 silicon, from 0.045 to 0.065 carbon, from 0.03 to 0.40 manganese, from 0.004 to 0.013 nitrogen, less than 0.012 sulfur, from 0.01 to 0.040 acid-soluble aluminum, less than 0.005 titanium, iron and unavoidable impurities, rest, continuous casting into a slab, heating slabs in a heating furnace, hot rolling, annealing hot rolled strips, cold rolling, continuous crystallization annealing decarburizing annealing of cold rolled strips in a moist nitrogen-hydrogen atmosphere and nitriding, applying a separating heat-resistant coating, high temperature annealing for pro conducting secondary recrystallization.
• steel is continuously poured onto the thickness of the finished slab 200-270 mm.
• slabs in a cooking oven will be interfered with at a surface temperature of slabs of at least 450 ° C. heated before hot rolling to a temperature of I l (K) - 12 (K) 0 C.
• the hot-rolled strip is annealed with heating and holding at a temperature of 1070 to 1200 0 C. then it is cooled at a speed of about 6 to 12 0 C / s to a temperature of from 900 to 980 0 C. maintained at this temperature, then sharply cooled from a temperature of 800-950 0 C at a speed of from 20 to 50 "Oc with water having a temperature of from 35 to 65 0 C,
• cold rolling is carried out in one or more stages.
• continuous annealing of the cold-rolled strip is carried out at a heating rate from 16 to 60 ° C / s to a temperature of 750-800 0 C, is kept at a decarburization temperature, nitriding is performed at a temperature of about 750 g to 850 ° C "in a nitrogen-hydrogen atmosphere containing ammonia NH 3 .
• Cold rolling is carried out in two stages, at the first stage cold rolling is carried out with a total reduction of 60 to 80% and additional heat treatment at a temperature of 150 to 300 0 C with a holding time of 3 minutes to 20 hours.
• Nitriding is carried out at the final stage of decarburization or after decarburization is completed at a temperature of from 770 to 820 0 C in a nitrogen-hydrogen atmosphere with a hydrogen content of more than 20%. water more than 0.5% ⁇ with a concentration of ammonia NH3 from 0.5 to 30%.
• the atmosphere for nitriding is obtained by passing nitrogen-hydrogen o i aia through an aqueous solution of ammonia NH3 with a concentration of 6-25% in the solution or by mixing gaseous ammonia NIh with the nitrogen-hydrogen atmosphere of the furnace.
• the temperature> pa of heating the slabs before hot rolling to 1,100 - 1,200 0 C improves the electromagnetic properties of anisotropic steel, and reduces scale formation at on the other hand in heating furnaces before hot rolling, to increase the productivity of the hot rolling mill, reduce fuel consumption when heating slabs, reduce metal consumption in steel production.
• a regulated cooling rate from a temperature of 1070-1200 0 C to a temperature of 900 to 980 0 C.
• continuous recrystallization decarburization annealing of cold-rolled strips in a humid nitrogen-hydrogen atmosphere and nitriding not only increase the share of higher grades in the total production volume, but also reduce the cost of production of anisotropic electrical engineering, and make it possible to receive ADVANCED income.
• the main second phase the inhibitor is aluminum nitrile.
• the formation of the conditions necessary to obtain the required parameters of the dispersed phase occurs at all technological stages, from smelting to high-temperature annealing for secondary recrystallization. In the proposed method, it is possible to distinguish three main stages of the formation of the dispersed phase of the required quantity and quality.
• the first stage is smelting, continuous casting into slabs, hot rolling.
• the second stage is the annealing of the hot rolled strip.
• the third stage is the continuous annealing of the cold-rolled strip. during which primary recrystallization, decarburization and nitriding are performed.
• the release and coagulation of aluminum nitride particles occurs.
• the parameters of the precipitated phase depend on the chemical composition of the steel, in particular, on the mass fraction of utrol. cooling rates and slab temperatures.
• the cooling rate is determined by the design features of the cooling system of the continuous slab casting (HPC). casting speed and slab thickness. By changing these parameters it is possible to influence the characteristics of the dispersed phase. However, as a rule, at already operating plants, a change in the casting regime, in addition to the thickness of the slabs, is possible within fairly narrow limits.
• the temperature of the heating of the slab should be 1200-1300 0 C.
• phase-forming elements can be obtained at a heating temperature of slabs before hot rolling to 1,100 - 1,200 0 C with the following process parameters: mass fraction of carbon in the metal during smelting from 0.045 lo 0.065 mass. % the thickness of the slabs is from 200 to 270 mm. the surface temperature of the slabs before being placed in the oven is not less than 450 0 C.
• Mass fraction of carbon in the range from 0.045 to 0.065 wt.%. allows you to get an increased amount of ⁇ -phase during the cycle cooling - heating and preservation of nitrogen in solution, i.e., its solubility in the ⁇ phases is much higher than in the ⁇ phase.
• the thickness of the slab from 200 to 270 mm provides the optimum cooling rate during casting, which prevents the formation of ⁇ ubmx inclusions of aluminum nitriles, and also due to the low thermal conductivity of silicon steel, at a surface temperature of at least 450 0 C allows you to keep the temperature from 700 0 in the central layers of the slab C and, accordingly, keep a sufficient number of phase-forming elements in the solution.
• the heating of slabs before hot rolling to a temperature of 1 100 - 1200 0 C. i.e. in the range corresponding to the maximum amount of the ⁇ -phase in the metal volume it allows you to translate and save a sufficient number of phase-forming elements in the solution.
• heating slabs before yarn rolling to a temperature of 1 100 - 1200 0 C allows to reduce scale formation during heating of slabs in a heating furnace, to reduce the time it takes to stop the heating furnace to clean the scale, and to increase the productivity of the hot rolling mill.
• the particles of the dispersed phase are modified, the carbon content is redistributed between the structural components, and the microstructure of the metal changes.
• inventive annealing parameters - temperature of heating and holding of 1100 lo 1200 ° C ⁇ a cooling rate of 6 to 12 ° C / c to temperatures of 900 to 980 0 C, holding at this temperature and rapid cooling from temperatures of 800 to 950 0 C at a rate of 20 to 50 ° C / c with water having a temperature of 35 to 65 0 C.
• a series of processes take place sequentially that provide the necessary structural state of the bell-string before cold rolling. Heating and holding at temperatures from 1,100 to 1,200 0 C.
• the cooling rate from 6 to 12 ° C / s to temperatures from 400 to 98O 0 C and exposure at this temperature provides the process of partial recovery of the nitride dispersed phase and the formation of its optimal size, as well as the redistribution of carbon content between ctp / ctyr components, what is necessary for the successful completion of the final stage of annealing - quenching.
• the claimed modes in addition to creating conditions for anisotropic articles with high magnetic properties, provide a strip with high ductility, which makes it possible to stabilize the cold rolling process, overhangs and to a minimum breaks of the strip, which are characteristic of cold rolling of high-silicon steel, and finally N NONE IF the productivity of the cold-rolling mill, to reduce the consumption of metal and> to improve the quality of the utility steel.
• the structure of the hot rolled strip is in a metastable state and the exposure between the operations of burning the hot rolled strip and cold rolling for more than 120 hours leads to the partial decomposition of the supersaturated solid solution and the formation of finely dispersed carbides. > ro leads, not only to a deterioration in the magnetic properties of the finished anisotropic electrical steel, but also to a deterioration in ductility and an increase in breakage during cold rolling.
• a certain texture state of a cold-rolled strip is an important condition for a number of texture transformations during the subsequent continuous annealing following cold rolling and, ultimately, for the formation of a perfect rib texture in finished steel.
• aging has a favorable effect on the texture of cold kneading and, ultimately, the level of magnetic properties of the finished steel — the precipitation of carbides on defects in the crystal lattice — performed between passes during cold rolling.
• the initiation of aging is achieved both by heat treatment of the strip in an intermediate thickness, rolled with reductions of 60 to 80% at a temperature of 150 to 300 0 C with a holding time of 3 minutes to 20 hours, and maintaining the temperature of the strip from 190 to 230 0 C due to heat strain in at least two passes.
• the heating of the strip during continuous annealing at a rate of from 16 to 60 0 CVc to a temperature of from 750 to 800 0 C prevents the coagulation and dissolution of the complex of fine particles of the second phase, the presence of which is necessary in the deformed matrix at the initial stage of primary recrystallization.
• Particles of the dispersed phase inhibit the growth of oriented grains. which differs from the Goss texture ⁇ 1 10 ⁇ ⁇ 001> and contribute to the formation of microregions with an orientation close to (1 10 ⁇ ⁇ 001>. which, transforming, ultimately provide grain growth with the indicated orientation during secondary recrystallization.
• the inhibitory phase contributes to the reduction of different grain sizes in the microstructure and thereby contributes to the controlled growth of primary recrystallization grains.
• a microstructure is formed with optimal grain size, different grain size and texture state.
• the amount of dispersed aluminum nitrides is insufficient to ensure that subsequent High-temperature annealing as a result of secondary recrystallization formed grains with a sharp Goss texture ⁇ 1 10 ⁇ ⁇ 001>.
• nitriding is carried out at a temperature of from 750 to 850 0 C. preferably at a temperature of r> 770 to 820 0 C in a nitrogen-hydrogen atmosphere with a hydrogen content of more than 20%. water more than 0.5%, ammonia concentration from 0.5 to 30%.
• the atmosphere containing ammonia is fed into the observation zone ⁇ coking in the final section, when the intensity of the dehydrocarburization process dies out and, at the same time, two processes occur - stripping of the carbon content at a decreasing rate up to its minimum content in the metal and saturation of the metal with nitrogen .
• each of these methods allows achieving the same result from the point of view of the magnetic properties of the finished article, but the unit in which the annealing is carried out. may have a different design. So. for example, in the first case, there may be no special zone with a furnace section for nitriding.
• Obtaining a nitrogen-hydrogen atmosphere for nitriding containing ammonia in the framework of the proposed method is possible by mixing the nitrogen-hydrogen atmosphere with pure ammonia or by passing the nitrogen-hydrogen atmosphere through an aqueous solution of ammonia with a concentration of 6-25% in the solution.
• the second method is the use of aqueous ammonia solution is simpler to implement and does not require compliance with a number of stringent conditions And special safety requirements required when using pure l ⁇ -shaped ammonia. Examples of carrying out the invention
• the first stage with a compression of 60 to 80% was performed in four stands in a m continuous four-roll cold rolling mill, intermediate processing was carried out in a continuous feed mill or in a baking furnace, the second cold rolling step was carried out on a reversing four-roll cold rolling mill continuous burning of the cold-rolled strip during which recrystallization was carried out, decarburization and nitriding were carried out in a continuous heat treatment unit, divided into zones and having a system for preparing and supplying a protective nitrogen-hydrogen atmosphere and ammonia to the furnace, a heat-resistant release coating was applied on a stand-alone unit, high-temperature ore was carried out at a temperature of 1200 0 C for 20 hours in a cage oven.

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• 2009
  • 2009-08-03 RU RU2009129885/02A patent/RU2407809C1/ru active
• 2010
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