CN113373372B - 1300 MPa-grade magnet yoke steel for manufacturing hydro-generator rotor and production method - Google Patents
1300 MPa-grade magnet yoke steel for manufacturing hydro-generator rotor and production method Download PDFInfo
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- CN113373372B CN113373372B CN202110575034.3A CN202110575034A CN113373372B CN 113373372 B CN113373372 B CN 113373372B CN 202110575034 A CN202110575034 A CN 202110575034A CN 113373372 B CN113373372 B CN 113373372B
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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
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- 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
- C21D8/1222—Hot rolling
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- 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
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- 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
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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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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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
- C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
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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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- 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
- C21D2211/004—Dispersions; Precipitations
-
- 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
Abstract
A1300 MPa-grade magnet yoke steel for manufacturing a hydro-generator rotor comprises the following chemical components in percentage by weight: c: 0.15 to 0.25%, Si: 0.45-0.55%, Mn: 1.8-2.0%, Nb: 0.04-0.06%, Mo: 0.20-0.30%, P: less than or equal to 0.015%, S: less than or equal to 0.002%, B: 0.002-0.003%, Als: 0.02-0.10%, RE: 0.30-0.40%; the production method comprises the following steps: continuously casting into a blank after smelting in a converter and refining by LF and RH; heating a casting blank; hot rolling after descaling; laminar cooling; coiling; quenching; tempering; and naturally cooling to room temperature. The yield strength of the steel is more than or equal to 1300MPa, the tensile strength of the steel is more than or equal to 1350MPa, the elongation of the steel is more than or equal to 10 percent, the magnetic induction performance B50 is more than or equal to 1.46T, the elements are simple, the production cost is lower, and the steel can completely meet the requirement of the steel for the rotor yoke of the hydraulic generator with the capacity of more than 1300MPa required by a single model of 130 ten thousand kilowatts.
Description
Technical Field
The invention relates to steel for a motor and a production method thereof, in particular to steel for a magnetic yoke of a hydraulic generator rotor and a production method thereof, which are more suitable for the use of the hydraulic generator rotor with the single-machine capacity of 130 kilokilowatts at 1300MPa or above.
Background
The rotor magnetic yoke in the hydraulic generator structure is one of the most core components, and the main function of the hydraulic generator structure is to generate rotational inertia and hang and install magnetic poles, and is also a part of a magnetic circuit. High strength, high precision and good magnetic properties are required. With the large-scale development of hydroelectric engineering, the rotor volume is continuously increased, and the safety performance requirement is also continuously improved, so that higher requirements are also provided for the strength of the magnetic yoke steel.
After retrieval: chinese patent application No. ZL201711087052.7 describes 'ultrahigh strength magnet yoke steel and a manufacturing method thereof', and the ultrahigh strength magnet yoke steel comprises the following chemical components in percentage by weight: 0.10 to 0.15, Si: less than or equal to 0.15, Mn: 1.85-2.00, P: 0.015 or less, S: less than or equal to 0.010, Ti: 0.20 to 0.30, Nb: 0.05 to 0.07, Mo: 0.35-0.55, B: 0.001 to 0.003, Als: 0.02-0.10, N: less than or equal to 0.010 percent, and the balance of Fe and inevitable impurities. After the steel plate is subjected to controlled rolling and controlled cooling treatment, the yield strength of the steel plate can only reach 900MPa, and the requirement of a single-machine capacity 130 ten thousand kilowatts hydraulic generator rotor on 1300MPa ultrahigh-strength magnet yoke steel cannot be met.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a magnetic induction property B with the yield strength of more than or equal to 1300MPa, the tensile strength of more than or equal to 1350MPa, the elongation of more than or equal to 9 percent50The yield strength of 1300MPa grade magnetic yoke steel for the hydraulic generator rotor can meet the single-machine capacity of 130 kilo-kilowatts, and the production method thereof.
The measures for realizing the aim are as follows:
a1300 MPa-grade magnetic yoke steel for manufacturing a hydraulic generator rotor comprises the following chemical components in percentage by weight: c: 0.15 to 0.25%, Si: 0.45-0.55%, Mn: 1.8-2.0%, Nb: 0.04-0.06%, Mo: 0.20-0.30%, P:
less than or equal to 0.015 percent, S: less than or equal to 0.002%, B: 0.002-0.003%, Als: 0.02-0.10%, RE: 0.30 to 0.40% by weight, and the balance Fe and inevitable impurities.
Preferably: the weight percentage content of the RE is 0.33-0.39%.
Preferably: the weight percentage of Mn is 1.83-1.93%.
Preferably: the weight percentage content of Nb is 0.045-0.055%.
A production method of 1300 MPa-grade magnet yoke steel for manufacturing a hydraulic generator rotor comprises the following steps:
1) continuously casting into a blank after smelting in a converter and refining by LF and RH;
2) heating a casting blank at 1180-1220 ℃;
3) carrying out hot rolling after descaling, and carrying out finish rolling at the finish rolling temperature of 850-900 ℃ by adopting the traditional two-stage rolling;
4) carrying out laminar cooling, and cooling to the coiling temperature at the cooling speed of 20-35 ℃/s;
5) coiling, wherein the coiling temperature is controlled to be 550-600 ℃;
6) quenching, wherein the quenching temperature is controlled to be 910-930 ℃;
7) tempering is carried out, the tempering temperature is controlled to be 300-350 ℃, and heat preservation is carried out for 50-100 min at the temperature;
8) naturally cooling to room temperature.
Preferably: the heating temperature of the casting blank is 1180-1200 ℃.
Preferably: the finishing temperature is 860-880 ℃.
Preferably: the coiling temperature is 550-580 ℃.
The action and mechanism of each element and main process in the invention
The content of carbon (C) is 0.15-0.25%, carbon is one of indispensable elements for improving the strength of steel in steel, and the magnetic induction performance of the steel is influenced by the excessively high content of carbon. The carbon content is limited to 0.15-0.25%, so that the strength of the steel can be improved, and the magnetic induction performance of the steel can be ensured.
The content of silicon (Si) is 0.45-0.55%, Si has solid solution strengthening effect and can improve hardenability. Si can reduce the diffusion speed of carbon in ferrite, so that carbide precipitated during tempering is not easy to gather, the tempering stability is improved, the strength and the hardness of the steel are improved along with the increase of the silicon, and crystal grains are coarsened when the content of the silicon exceeds a certain range, so that the content of the Si is controlled to be 0.45-0.55 percent.
The content of manganese (Mn) is 1.8-2.0%, the manganese can reduce the phase transition temperature of austenite transformed into ferrite, expand the hot working temperature area, be beneficial to refining the ferrite grain size and improve the yield strength and tensile strength of steel. However, if the Mn content is too high, the temper brittleness and center segregation of the steel are increased, so the Mn content is controlled to be 1.8-2.0 percent by the invention.
The content of niobium (Nb) is 0.04-0.06%, and trace niobium can obviously refine grains and improve the tensile strength of the steel. In the controlled rolling process, niobium can improve the recrystallization temperature of steel, reduce the load of a rolling mill and facilitate the control of plate shape. Meanwhile, the austenite grain size can be refined by inhibiting recrystallization and preventing grain growth. In the cooling process after rolling, the small particles of NbC and NbN are separated out, and can play a role in strengthening precipitation. Therefore, the content of niobium (Nb) in the invention is 0.04-0.06%.
The content of molybdenum (Mo) in the invention is 0.20-0.30%, and molybdenum exists in solid solution and carbide of steel and has the function of solid solution strengthening. When molybdenum and niobium are added simultaneously, the molybdenum can increase the inhibition of austenite recrystallization in the controlled rolling process, thereby promoting the refinement of the austenite microstructure. Meanwhile, Mo has better tempering stability, and is beneficial to the performance stability of the steel after tempering. Therefore, the content of molybdenum (Mo) in the invention is 0.20-0.30%
The invention has the phosphorus (P) content less than or equal to 0.015 percent and the sulfur (S) content less than or equal to 0.002 percent, the phosphorus is easy to cause segregation in steel, and the sulfur is easy to combine with manganese to generate MnS inclusion, which are both unfavorable for strength. Therefore, the adverse effects of phosphorus and sulfur on the magnetic properties and strength of the steel should be minimized, and the P, S content of the steel is controlled to be P: 0.015 or less, S: less than or equal to 0.002.
The content of boron (B) is 0.002% -0.003%, B has the main function of improving the hardenability of steel, and boron is taken as a surface active element, is adsorbed on austenite grain boundaries, delays the transformation from austenite to ferrite, and is segregated in the austenite grain boundaries to block the nucleation of ferrite, thereby being beneficial to the formation of martensite and further improving the structure strengthening effect. However, the B content is too high, the hardenability is lowered, and eutectic crystals having a low melting point are formed and concentrated on the grain boundaries, thereby causing hot brittleness. Therefore, the boron content range of the invention is 0.002% -0.003%.
The content of Rare Earth (RE) in the invention is 0.30-0.40%: the strength and magnetic performance of the yoke steel are a pair of spears, because the grain boundary and the precipitated phase have a pinning effect on the movement of a domain wall while the strength of the steel plate is improved through fine grain strengthening and precipitation strengthening, and the magnetic induction performance is reduced. Meanwhile, the magnetism of the rare earth element is derived from an unfilled 4f electron layer, and atoms or molecules containing odd electrons are generally added into steel, so that the magnetism of the steel plate can be improved. Therefore, in order to obtain high strength and high magnetic induction properties at the same time, the RE element having high magnetic properties is added along with the addition of the reinforcing element to obtain high strength and high magnetic induction properties at the same time.
The rare earth has obvious solid solution strengthening effect, the solid solution rare earth is mainly distributed in a crystal boundary, the interfacial tension and the interfacial energy are reduced, and the driving force for the growth of crystal grains is reduced, so that the growth of austenite crystal grains is inhibited, and the crystal grains are refined. Meanwhile, the rare earth can promote the precipitation of microalloy elements, enhance the precipitation strengthening effect, and enrich the grain boundary through a diffusion mechanism, thereby reducing the segregation of impurity elements in the grain boundary and strengthening the grain boundary. In addition, the rare earth has better magnetism, can effectively improve the magnetic property of the steel plate, and comprehensively considers that the RE content range of the invention is 0.30-0.40%.
The heating temperature is controlled to be 1180-1220 ℃, so that complete solid solution and full austenitization of alloy elements are ensured, the temperature uniformity of a plate blank is improved, the deformation resistance and the rolling load are reduced, and the thin-specification magnetic yoke steel is favorably rolled.
The invention controls the finishing temperature to be 850-900 ℃, the coiling temperature to be 550-600 ℃, and the invention mainly refines austenite grains and improves the strength of the steel after heat treatment.
The invention controls the quenching heating temperature to be 910-930 ℃, namely Ac3+ (70-90) DEG C, and mainly coarsens original austenite grains, reduces the barrier effect of austenite grain boundaries on magnetic domain walls, obtains good magnetic performance, and simultaneously avoids oversize structures, thereby obtaining refined quenched martensite structures and improving the strength of steel.
The tempering heating temperature is controlled to be 300-350 ℃ and the heat preservation time is 50-100 min. Supersaturated carbon atoms in the quenched martensite are desolventized to form fine carbide particles through a tempering process, the strength of the steel plate is further improved, the plasticity of the steel is improved, the carbide particles grow rapidly when the tempering temperature is too high or the heat preservation time is too long, and the yield strength of the steel plate can be obviously reduced. And comprehensively considering the strength and the plasticity, finally setting the tempering heating temperature to be 300-350 ℃, and keeping the temperature for 50-100 min.
Compared with the prior art, the invention has the yield strength of more than or equal to 1300MPa, the tensile strength of more than or equal to 1350MPa, the elongation of more than or equal to 9 percent and the magnetic induction property B50The yield strength of the rotor is not less than 1.46T, the elements are simple, and the yield strength can completely meet the requirement of 1300MPa for preparing a hydrogenerator rotor with the capacity of 130 ten thousand kilowatts per unit.
Detailed Description
The present invention is described in detail below:
table 1 is a list of values of the components of each example and comparative example of the present invention;
table 2 is a list of process parameter values and performance tests for each example and comparative example of the present invention.
The preparation method comprises the following steps:
1) continuously casting into a blank after smelting in a converter and refining by LF and RH;
2) heating a casting blank at 1180-1220 ℃;
3) carrying out hot rolling after descaling, and carrying out finish rolling at the finish rolling temperature of 850-900 ℃ by adopting the traditional two-stage rolling;
4) carrying out laminar cooling, and cooling to the coiling temperature at the cooling speed of 20-35 ℃/s;
5) coiling, wherein the coiling temperature is controlled to be 550-600 ℃;
6) quenching, wherein the quenching temperature is controlled to be 910-930 ℃;
7) tempering is carried out, the tempering temperature is controlled to be 300-350 ℃, and heat preservation is carried out for 50-100 min at the temperature;
8) naturally cooling to room temperature.
TABLE 1 list of chemical compositions (wt%) of inventive and comparative examples
TABLE 2 Main Process and test results for examples of the invention and comparative examples
As can be seen from the results in Table 2, the yield strength of the steel plate is more than or equal to 1300MPa, the tensile strength is more than or equal to 1350MPa, the elongation is more than or equal to 10%, the magnetic induction performance B50 is more than or equal to 1.46T, the steel plate has ultrahigh strength and good magnetic performance, and can meet the requirements of 1300 MPa-level magnetic yoke steel plates for manufacturing hydraulic generator rotors.
The above examples are merely preferred examples and are not intended to be exhaustive of the technical aspects of the present invention.
Claims (5)
1. A1300 MPa-grade magnetic yoke steel for manufacturing a hydraulic generator rotor comprises the following chemical components in percentage by weight: c: 0.21 to 0.25%, Si: 0.45-0.55%, Mn: 1.8-2.0%, Nb: 0.052-0.06%, Mo: 0.21-0.29%, P: less than or equal to 0.015 percent, S: less than or equal to 0.002%, B: 0.0026 to 0.003%, Als: 0.04-0.10%, RE: 0.30-0.40%, and the balance of Fe and inevitable impurities;
the production method comprises the following steps:
1) continuously casting into a blank after smelting in a converter and refining by LF and RH;
2) heating a casting blank at 1180-1220 ℃;
3) carrying out hot rolling after descaling, and carrying out finish rolling at the finish rolling temperature of 850-900 ℃ by adopting the traditional two-stage rolling;
4) carrying out laminar cooling, and cooling to the coiling temperature at the cooling speed of 20-35 ℃/s;
5) coiling, wherein the coiling temperature is controlled to be 550-600 ℃;
6) quenching, wherein the quenching temperature is controlled to be 910-930 ℃;
7) tempering is carried out, the tempering temperature is controlled to be 300-348 ℃, and heat preservation is carried out for 50-100 min at the temperature;
8) naturally cooling to room temperature.
2. A 1300MPa grade yoke steel for manufacturing a hydro-generator rotor according to claim 1, wherein: the weight percentage content of the RE is 0.33-0.39%.
3. A 1300MPa grade yoke steel for manufacturing a hydro-generator rotor according to claim 1, wherein: the weight percentage of Mn is 1.83-1.93%.
4. A production method of 1300MPa grade yoke steel for manufacturing hydro-generator rotor according to claim 1, comprising the steps of:
1) continuously casting into a blank after smelting in a converter and refining by LF and RH;
2) heating a casting blank at 1180-1220 ℃;
3) carrying out hot rolling after descaling, and adopting the traditional two-stage rolling, wherein the finish rolling temperature is 850-900 ℃;
4) carrying out laminar cooling, and cooling to the coiling temperature at the cooling speed of 20-35 ℃/s;
5) coiling, wherein the coiling temperature is controlled to be 550-600 ℃;
6) quenching, wherein the quenching temperature is controlled to be 910-930 ℃;
7) tempering is carried out, the tempering temperature is controlled to be 300-348 ℃, and heat preservation is carried out for 50-100 min at the temperature;
8) naturally cooling to room temperature.
5. The production method of 1300MPa grade yoke steel for manufacturing a hydro-generator rotor according to claim 4, wherein: the coiling temperature is 550-580 ℃.
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Citations (2)
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CN1840723A (en) * | 2005-03-30 | 2006-10-04 | 宝山钢铁股份有限公司 | Superhigh strength steel plate with yield strength more than 1100Mpa and method for producing same |
CN107794448A (en) * | 2017-11-07 | 2018-03-13 | 武汉钢铁有限公司 | A kind of high-strength steel sheet and its manufacture method with excellent magnetic energy |
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CN1840723A (en) * | 2005-03-30 | 2006-10-04 | 宝山钢铁股份有限公司 | Superhigh strength steel plate with yield strength more than 1100Mpa and method for producing same |
CN107794448A (en) * | 2017-11-07 | 2018-03-13 | 武汉钢铁有限公司 | A kind of high-strength steel sheet and its manufacture method with excellent magnetic energy |
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