CN115627425A - Metal material and preparation and application thereof - Google Patents

Metal material and preparation and application thereof Download PDF

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Publication number
CN115627425A
CN115627425A CN202211146047.XA CN202211146047A CN115627425A CN 115627425 A CN115627425 A CN 115627425A CN 202211146047 A CN202211146047 A CN 202211146047A CN 115627425 A CN115627425 A CN 115627425A
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ferrite
region
nitriding
metal material
area
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王华君
叶平元
李九鼎
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Wuhan Liangyi Materials Co ltd
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Wuhan Liangyi Materials Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • 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
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/24—Nitriding
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/02—Details of the magnetic circuit characterised by the magnetic material
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/22—Rotating parts of the magnetic circuit
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K15/00—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines
    • H02K15/02—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies
    • 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
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/64—Electric machine technologies in electromobility

Abstract

The invention belongs to the technical field of metal materials, and particularly provides a metal material and preparation and application thereof, wherein the preparation method comprises the steps of selecting a local area on a plate only containing a ferrite area to carry out solid solution nitriding to obtain the metal material, and forming a non-ferrite area in the local area after the solid solution nitriding; wherein the ferrite content in the ferrite region is more than 90%, the main elements in the ferrite region comprise Fe, cr, mn and Mo, the Cr content is 20-26 wt.%, the Mn content is 2-8 wt.%, and the Mo content is 0.5-2 wt.%; the interface between the ferritic and non-ferritic regions is a strong bond with phase transformation in grain size. The metal material is used for the motor rotor lamination, so that the magnetic flux loss of the motor rotor lamination can be reduced, and the mechanical strength of the motor rotor lamination is improved.

Description

Metal material and preparation and application thereof
Technical Field
The invention relates to the technical field of metal materials, in particular to a metal material and preparation and application thereof, and specifically relates to a near ferrite stainless steel plate material and preparation and application thereof in motor rotor lamination.
Background
The need for high power density and high efficiency electric machines has long been prevalent in a variety of applications, particularly in hybrid and electric vehicle traction applications. The development trend of the application of the traction motor of the hybrid power and electric automobile at present is to improve the power density of the motor by increasing the rotating speed, thereby reducing the quality and the cost of the motor. However, it is recognized that there are significant tradeoffs between power density, efficiency, and the constant power speed range of the machine when the electric machine is used in hybrid and electric vehicle traction applications, which present many design challenges.
The power density of the machine can be increased by increasing the machine size, improving thermal management, increasing the rotor speed, or by increasing the field utilization. The traditional motor rotor is formed by laminating silicon steel sheets, the outer circle outline of the laminated sheets is in a tooth shape, air or fluid exists in a gap between the rotor and the stator during the working process, and a large amount of mechanical loss is generated due to the stirring of the air or the fluid in the air gap between the rotor and the stator, and the loss is more obvious particularly in some high-speed working motors. In order to reduce the mechanical loss caused by such reasons, a magnetic bridge structure is generally used to reduce the stirring of the gas, but the magnetic bridge structure leaks magnetic flux, resulting in the loss of magnetic flux.
The motor with the magnetic bridge structure is used as a novel motor, and the technical key for improving the performance of the motor is to reduce magnetic leakage and improve the salient pole ratio of the laminated sheet. The current solution to the magnetic leakage problem includes the use of a multi-layer rotor and a magnetic bridge to thin the rotor, and both of these approaches seek a high salient pole ratio, reduce the magnetic leakage and bring about the problem of mechanical strength.
In view of this, the present invention is proposed.
Disclosure of Invention
The invention provides a metal material with local solid solution nitriding, a preparation method and an application thereof, in particular to a near ferrite stainless steel plate material, a preparation method and an application thereof in a motor rotor lamination, which are used for solving the defect that a magnetic bridge of a motor rotor lamination in the prior art cannot simultaneously meet the requirements of laminations in a high-power-density motor and a high-rotating-speed motor on a salient pole ratio, magnetic leakage and mechanical strength.
The present invention provides a metal material comprising: a ferrite region and a non-ferrite region;
the ferrite area contains more than 90% of ferrite, wherein the main elements of the ferrite comprise Fe, cr, mn and Mo, the content of Cr is 20-26 wt.%, the content of Mn is 2-8 wt.%, the content of Mo is 0.5-2 wt.%, and other elements are as follows: 0.001-0.04 wt.% of C, 0.1-0.5 wt.% of Al, 0.5-1 wt.% of Si, and the balance of Fe; the other phases in the ferrite region are a small amount of austenite or martensite.
In the raw materials, cr is an element with strong affinity with nitrogen, so that the nitriding process can be promoted, and the nitriding efficiency can be improved; meanwhile, cr belongs to an element defined by Cr equivalent, the element defined by Cr equivalent is a ferrite generating element, and the Cr content can ensure that a base material before nitriding is a ferrite structure.
Mn is an element with strong affinity with nitrogen, can promote the occurrence of a nitriding process and improve the nitriding efficiency; mn belongs to an element defined by Ni equivalent, the element defined by Ni equivalent is an austenite generating element, the range of Mn content is reasonably controlled, the base material before nitriding can be ensured to be a ferrite structure, and the solid solution nitriding efficiency is improved.
Mo is an element with strong affinity with nitrogen, can promote the occurrence of a nitriding process and improve the nitriding efficiency, and the Mo element is added for further adjusting the magnetic domain property of the microstructure of the raw material and improving the magnetic permeability and the magnetic induction intensity of the raw material.
The alloy elements Cr, mn and Mo can reduce the martensite transformation line of the alloy, so that the structure obtained by immediately quenching the solution-nitrided coating-free region without seepage control nitrogen is retained as austenite and cannot be transformed into martensite.
The content of austenite in the non-ferrite area is more than 70%, and the nitrogen content in the non-ferrite area is 0.4-1.2 wt% according to different nitriding times; the invention controls the nitrogen content of the non-ferrite area, which is the basic condition for obtaining austenite by local solution nitriding, the original structure can not be fully converted into austenite by the ferrite when the nitrogen content of the non-ferrite area is lower than the value, the nitrogen content in the matrix structure can be supersaturated when the nitrogen content is higher than the value, and the nitrogen element and the alloy element Cr and the like can further obtain nitrides such as chromium nitride, iron nitride and the like. Furthermore, the local austenite region is also a key factor for improving the mechanical property and the magnetic property of the motor rotor lamination, so that the nitrogen content is required to be controlled to ensure the obtained high-nitrogen austenite.
The boundary between the ferrite area and the non-ferrite area is firmly combined by phase transformation on grain size.
According to the metal material provided by the invention, the ferrite area is a matrix structure described by a specific area in a Schaeffer stainless steel structure phase diagram, and the specific area means that the equivalent ratio occupied by each element of the ferrite area satisfies the following formula: cr (chromium) component Equivalent weight ＝Cr％+Mo％+1.5×(Si％+V％)+0.8W％+0.5Nb％+4Ti％+3.5Al％；
Ni Equivalent weight ＝Ni％+Co％+30×(C％+N％)+0.5Mn％+0.33Cu％。
The invention relates to a slave motor rotorStarting from the requirements of the tissue composition and magnetism of the lamination, establishing a material selection basis suitable for the motor rotor lamination by combining with the Schaeffer stainless steel tissue phase diagram, and according to the Schaeffer stainless steel tissue phase diagram and Cr Equivalent weight And Ni Equivalent weight The microstructure of the material at room temperature can be influenced, so that the equivalent ratio occupied by each element in the ferrite is set to satisfy the following formula:
Cr equivalent weight ＝Cr％+Mo％+1.5×(Si％+V％)+0.8W％+0.5Nb％+4Ti％+3.5Al％；
Ni Equivalent weight ＝Ni％+Co％+30×(C％+N％)+0.5Mn％+0.33Cu％。
According to the metal material provided by the invention, the Cr in the ferrite region Equivalent weight More than 20wt.% and less than 30wt.%, ni Equivalent weight Greater than 1wt.% and less than 8wt.%.
In the invention, cr is arranged Equivalent weight And Ni Equivalent weight Within the above range, this makes the soft magnetic property of the ferrite region of the present invention more excellent, wherein when there is higher Cr equivalent and lower Ni equivalent, the structure is ferrite only, and the soft magnetic property is better, and the high Cr equivalent and the proper Ni equivalent are controlled to adjust the matrix material to obtain high nitrogen solubility, and the higher Cr and proper Mn, mo content are favorable for nitriding efficiency, and oxidation and the like caused by too long high temperature time of the plate are avoided, and here, the overall optimization based on material composition, solution treatment process and material property is performed.
According to the metal material provided by the invention, the non-ferrite area is obtained by the ferrite area through a local solution nitriding mode, and the amount of other elements except nitrogen in the non-ferrite area is not changed before and after nitriding.
According to the metal material provided by the invention, the metal material is a plate, and the interface of the ferrite area and the non-ferrite area penetrates through the thickness direction of the plate.
According to the metal material provided by the invention, the boundary of the ferrite area and the non-ferrite area is formed by the local solution nitriding process.
The invention also provides a preparation method of the metal material, which is characterized in that a local area is selected on the surface of the plate only containing the ferrite area to carry out solid solution nitriding to obtain the metal material;
the local region forms a non-ferrite region after solution nitriding.
Solution nitriding is a process in which nitrogen is added to a steel matrix, which can be made austenitic at room temperature when the nitrogen content reaches a certain level, and austenite is a non-magnetic phase. The motor rotor lamination is subjected to local solid solution nitriding, the magnetic bridge is austenitized to obtain a non-magnetic bridge, and the addition of nitrogen can enhance the bonding force of a crystal boundary, prevent crystal grains from growing and achieve the effect of solid solution strengthening, so that the strength and toughness of the magnetic bridge are improved, and the magnetic bridge is prevented from being broken and damaged in high-speed rotation. However, pure iron and silicon steel have very low solubility to nitrogen, so it is important to study the relationship between alloy elements, structure and material magnetism and determine the material basis suitable for solid solution nitriding. The invention optimizes the material components of the plate only containing ferrite area, and can obtain the material with double-phase area of magnetic conduction and non-magnetic conduction through the solution nitriding of local area.
The preparation method of the metal material provided by the invention comprises the following specific steps: firstly, coating a part of area on the surface of a plate only containing a ferrite area with a nitrogen impermeable coating or copper plating, then putting the coated plate into a nitrogen-filled high-temperature and high-pressure environment for solid solution and nitriding, taking out and immediately quenching;
the high-temperature and high-pressure environment is generally a high-temperature and high-pressure furnace;
and continuously introducing nitrogen with the purity of more than 99.99 percent in the solid solution nitriding process.
Said partial area and said partial area constitute the entire surface of said block.
The nitrogen is dried nitrogen with the purity of 99.99 percent, the nitrogen is always in a flowing state in the solid solution nitriding process, the nitrogen pressure is 0.25MPa, and the method is a rapid solid solution nitriding technology with high-pressure gas circulation.
In order to obtain stable austenite structure at room temperature of the magnetic bridge and avoid generating harmful nitride precipitated phase, the magnetic bridge is rapidly cooled immediately after the solution nitriding, wherein the rapid cooling can adopt air quenching, water quenching and oil quenching, the invention selects a proper cooling method according to the thickness of the plate, for example, a thin plate with the thickness of 0.1 mm-0.8 mm can adopt air quenching or high-pressure gas quenching, and a plate with the thickness of 0.8 mm-1.5 mm can adopt water quenching or oil quenching.
According to the preparation method of the metal material provided by the invention, the temperature range in the high-temperature and high-pressure environment is 1000-1200 ℃, and the pressure range is 0.1-0.5 MPa; the time range of the solid solution nitriding is 0.3 h-4 h.
The process can realize different nitriding layer depths of 0.1 mm-1.5 mm.
The thicker the plate is, the longer the selected solid solution nitriding heat preservation time is, at least 70% of tissues in the nitrided area are subjected to austenite transformation, the maximum magnetic permeability is about 1, and the magnetic induction intensity is about 0.
According to the preparation method of the metal material provided by the invention, the plate is a rolled plate with the thickness of 0.1-1.5 mm. The heat treatment process of rolling can adopt annealing treatment, the annealing temperature is 550-650 ℃, and the heat preservation time is 1-2h.
The thickness of the motor rotor lamination is consistent with that of the traditional motor rotor lamination, and the nitriding depth in the whole thickness direction is obtained in the solid solution nitriding process of 0.3-4 h.
According to the preparation method of the metal material provided by the invention, before the solid solution nitriding, the surface of the rolled plate is polished by adopting a polishing machine or a sand blasting mode to remove a surface oxidation layer, and then the rolled plate is cleaned by absolute ethyl alcohol and dried by blowing.
According to the preparation method of the metal material provided by the invention, quenching is carried out immediately after solid solution nitriding is finished, then annealing treatment is carried out on the plate, and then the residual nitrogen-impermeable coating on the surface of the plate is brushed or soaked in an acid solution to remove the nitrogen-impermeable coating.
Annealing treatment eliminates internal stress, improves magnetism, increases maximum magnetic conductivity and magnetic induction intensity, removes residual anti-seepage nitrogen coating on the surface of the plate, and removes oxides on the surface.
According to the preparation method of the metal material provided by the invention, the copper plating refers to plating the copper with the thickness ranging from 0.035mm to 0.06mm on the surface of the plate except the position of the local area, so as to avoid nitriding in the non-nitriding area.
According to the preparation method of the metal material provided by the invention, the step of coating the anti-nitriding coating is to adopt spraying, dip-coating or brush-coating anti-nitriding coating at the position of the non-local area of the plate, then put the plate into an oven, keep the temperature for 0.5 to 1 hour at 100 to 150 ℃, and carry out solid solution nitriding on the local area after the coating is dried;
the coating material used by the invention is high-temperature anti-seepage nitrogen paint, and the coating has the high temperature resistance of 1100 +/-100 ℃, and can prevent nitrogen atoms from reacting with metal in the area coated with the coating.
The invention also provides the application of the metal material, which is applied to the motor rotor lamination;
the non-ferrite area is used as a magnetic bridge of a motor rotor lamination;
the magnetic bridge is high-nitrogen austenite which is non-magnetic and high in mechanical strength, so that the motor rotor lamination does not have magnetic leakage and magnetic flux loss in the working process; the tensile strength of the magnetic bridge is improved by more than 50%, and the magnetic bridge is corrosion-resistant and high-temperature-resistant, and does not break or lose efficacy when rotating at high speed.
According to the metal material and the preparation and application thereof, the components of the metal material are optimized, a local solid solution nitriding process is adopted to austenitize a target region, and soft magnetism is reserved in other regions.
Compared with the common silicon steel, the metal material plate contains more alloy elements, and has good mechanical property and corrosion resistance.
The motor rotor lamination made of the metal material plate has the advantages that the austenite magnetic bridge and the ferrite of the lamination are combined by grain size phase change instead of welding and cementing in the traditional mode, the strength of the magnetic bridge is further improved, and the magnetic bridge is prevented from breaking and losing efficacy at high rotating speed.
Compared with the traditional silicon steel lamination with a magnetic bridge structure, the traditional silicon steel lamination has magnetic leakage, and the invention selects near ferrite (ferrite area in Schaeffer diagram and tissues near the ferrite area) in order to utilize the soft magnetism of ferrite, but the nitriding efficiency of the traditional pure iron and low alloy ferrite materials is extremely low, and the materials are difficult to austenitize after solution nitriding, and an alloy material with high chromium, manganese and molybdenum is selected here, and the saturated solubility of nitrogen of the material components is high, so that the material can be subjected to solution nitriding in a local area, and the nitriding can cause nitrogen addition in the magnetic bridge area of the motor rotor lamination to generate lattice recombination, thereby obtaining a nonmagnetic magnetic bridge with a stable austenite structure at room temperature, and further solving the magnetic flux loss of the motor rotor lamination structure.
The motor rotor lamination made of the metal material plate has better magnetic property after complete annealing, particularly the magnetic bridge area is high-nitrogen austenite without magnetism leakage, so that the magnetic flux of the motor rotor lamination is not lost, the reluctance torque and the power density are higher, the motor rotor lamination has stronger mechanical strength, the defect that the magnetic conductivity of the initial material is not as good as that of silicon steel is overcome, finally, the overall magnetic property of the motor lamination is superior to that of the traditional silicon steel lamination, and a material selection scheme and a heat treatment process thereof are provided for a high-power-density motor, a high-rotating-speed motor and a motor in a corrosion-resistant environment.
Drawings
In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic distribution diagram of the Schaeffer stainless steel texture phase diagram of the areas in the plate of the present invention;
FIG. 2 is a schematic structural view of a motor rotor lamination of the present invention;
FIG. 3 is an SEM image of a cross section of a metal material of the present invention;
FIG. 4 is an XRD pattern of the sheet of the present invention before and after solution nitriding;
FIG. 5 is a tensile strength curve of the inventive sheet before and after solution nitriding;
FIG. 6 is hardness of the plate of the present invention before solution nitriding;
FIG. 7 is the hardness of the plate of the invention after 3h solution nitriding;
FIG. 8 is a magnetic pole observation sheet result of the plate of the present invention before solution nitriding;
FIG. 9 is a magnetic pole observation sheet result of the plate of the present invention after 3h of solution nitriding;
FIG. 10 is a hysteresis loop of a plate of the present invention before solution nitriding;
FIG. 11 is a hysteresis loop of the plate of the present invention after solution nitriding for 3 hours;
reference numerals:
1: magnetic bridge, 2: magnetic conduction structure, 3: an air gap.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
A metal material of the present invention, its preparation and use are described below with reference to fig. 1 to 11.
The test method of the invention is as follows:
the phase composition of the non-ferritic regions of the sheet is determined by X-ray diffraction analysis (XRD);
the nitrogen content of the nitrided plate is tested by a nitrogen element chemical test method, and the method is more accurate compared with the traditional method for testing elements by energy spectrum (EDS);
testing the surface hardness of the plate by a Vickers hardness tester;
testing the tensile strength of the plate before and after the solid solution nitriding of the material through a tensile experiment;
observing the tissue structure of the plate before and after nitriding through a Scanning Electron Microscope (SEM);
the magnetic conductivity of the plate before and after nitriding is observed through a magnetic pole observation sheet;
and testing the magnetic properties of the plate, such as magnetic permeability, coercive force and the like before and after nitriding by using a soft magnetic direct current B-H instrument.
Example 1
A preparation method of a metal material comprises the following specific steps:
(1) Selecting materials to be rolled into a rolled plate with the thickness of 0.5 mm; the structure schematic diagram of the rolled plate is shown in figure 2, the structure of the rolled plate is the same as that of a motor rotor lamination, the rolled plate consists of a magnetic bridge 1 (nitriding region), an air gap 3 and a magnetic conduction structure 2 (non-nitriding region), the rolling heat treatment process is annealing treatment, the annealing temperature is 600 ℃, and the heat preservation time is 1.5 hours.
The elemental composition of the selected material is: fe. Cr, mn, mo and other elements, and the value range of Cr is 22wt.%, the value range of Mn is 4wt.%, the value range of Mo is 0.75wt.%, and the other elements are: 0.001wt.% C, 0.1wt.% Al, 0.5wt.% Si, balance Fe; as shown in fig. 1, the material of example 1 is described in connection with the phase diagram of the Schaeffer stainless steel structure, and the structure of the obtained plate is ferrite with a content of more than 99%, and the rest phase is a small amount of austenite or martensite.
The magnetic properties of the rolled sheet were tested and the results were: the maximum magnetic permeability is 1000 and the magnetic induction intensity is 1T.
(2) And polishing the surface of the rolled plate by adopting a sand blasting mode, removing a surface oxide layer, cleaning by using absolute ethyl alcohol and drying by blowing.
(3) Firstly coating a nitrogen seepage prevention coating on a non-nitriding area on a rolled plate, then putting the whole plate into a high-temperature high-pressure furnace filled with nitrogen for solution nitriding, taking out and immediately quenching;
wherein, the nitrogen seepage preventing coating is a high-temperature nitriding preventing coating sold in the market; coating the anti-nitriding coating means that firstly, spraying, dip-coating or brush-coating the anti-nitriding coating on the plate except the position of a local area, then putting the plate into an oven, keeping the temperature for 0.5h at 100 ℃, and carrying out solid solution nitriding on the local area after the coating is dried;
continuously introducing nitrogen with the flow purity of 99.99 percent in the solid solution nitriding process; the temperature in the high-temperature and high-pressure environment is 1100 +/-100 ℃, and the pressure is 0.2MPa; the time of solid solution nitriding is 3h;
the quenching mode is that the plate after the solid solution nitriding is immediately put into water for water quenching, and the plate is taken out after being completely cooled to the room temperature.
(4) And annealing the plate, and brushing the residual anti-seepage nitrogen coating on the surface of the plate to obtain the metal material.
The metal material was tested:
the results of the phase analysis method according to XRD are: as shown in fig. 4, only the diffraction peak of ferrite in the non-nitrided region is consistent with the phase analysis result of XRD of the sheet in step (1), and the region is still the material and the structure of the sheet in step (1) (i.e., ferrite region); the nitriding region has an austenite diffraction peak, and the content of austenite in the region is calculated to be more than 70 percent (namely a non-ferrite region) by using XRD analysis software MDI Jade 6 according to the intensity of the XRD diffraction peak; the interface of the ferrite area and the non-ferrite area is formed by the solid solution nitriding process, and the interface of the ferrite area and the non-ferrite area penetrates through the thickness direction of the plate.
According to the method for chemically testing nitrogen elements, the test result is as follows: the ferritic region contains no nitrogen, while the non-ferritic region after nitriding contains 0.6wt.%.
According to the test of the soft magnetic B-H measuring instrument, the test result is as follows: the magnetic properties of the ferrite region are: the maximum magnetic permeability is 1000, and the magnetic induction intensity is 1.3T, which shows that the soft magnetic performance of the substrate material after annealing is better. The magnetic properties of the non-ferrite region are: the maximum magnetic permeability is 1, and the magnetic induction intensity is 0, which shows that the non-ferrite area is a non-magnetic austenite structure after local solution nitriding.
Microstructure observation by SEM, as shown in fig. 3, the test results were: the grains of ferrite and austenite are clearly visible under 500 times electron microscope observation, and it is also observed that the interface of the ferrite area and the non-ferrite area is a strong bond of phase transformation in grain size.
The hardness test is carried out by a Vickers hardness tester, as shown in figures 6 and 7, points are randomly selected on the plate when the hardness test is carried out, and the test result shows that: the average hardness of the plate before nitriding is 287HV0.5, the average hardness of the plate after nitriding is 417HV0.5, and the hardness of the material can be obviously improved through solution nitriding treatment.
(5) Applying the prepared metal material as a motor rotor lamination; wherein the non-ferrite area is used as a magnetic bridge of the motor rotor lamination; the magnetic bridge has no magnetic leakage and no magnetic flux loss; the magnetic bridge is corrosion resistant and high temperature resistant.
Example 2
A preparation method of a metal material comprises the following specific steps:
(1) Selecting materials to be rolled into a rolled plate with the thickness of 0.5mm, wherein the rolling heat treatment process is annealing treatment, the annealing temperature is 600 ℃, the heat preservation time is 1.5h, and cutting the plate with the thickness of 40mm multiplied by 100mm to carry out a solution nitriding experiment.
The elemental composition of the selected material is: fe. Cr, mn, and Mo, wherein the value range of Cr is 21wt.%, the value range of Mn is 6.5wt.%, the value range of Mo is 1wt.%, and the other elements are: 0.001wt.% C, 1wt.% Si, balance Fe; the material of example 2 is described in connection with the Schaeffer stainless steel microstructure phase diagram, and the structure of the produced plate is more than 99% of ferrite, and the rest phase is a small amount of austenite or martensite.
(2) And polishing the surface of the rolled plate by adopting a polishing machine to remove a surface oxide layer, and then cleaning and drying the rolled plate by using absolute ethyl alcohol.
(3) Firstly, plating copper in a non-nitriding area on a rolled plate, then putting the whole plate into a high-temperature high-pressure furnace filled with nitrogen for solution nitriding, taking out and immediately etching for water quenching;
the copper plating is to plate copper with a thickness of 0.06mm (thicker as the solution nitriding time is longer) on the surface of the plate except for the local region.
Continuously introducing nitrogen with the purity of 99.99 percent in the solid solution nitriding process; the temperature in the high-temperature and high-pressure environment is 1150 +/-50 ℃, and the pressure is 0.25MPa; the time of solution nitriding is 3h.
(4) And (3) annealing the plate, removing the residual copper plating layer on the surface without influencing the use, and cleaning the residual oxide and oil stain on the surface of the plate to obtain the metal material.
The metal material was tested:
the phase analysis test method according to XRD, like example 1, results in: the non-nitrided region is still 99% or more of ferrite (i.e., ferrite region); the content of austenite in a nitriding region is more than 70% (namely a non-ferrite region); the boundary of the ferrite area and the non-ferrite area is formed by the solid solution nitriding process, and the interface of the ferrite area and the non-ferrite area penetrates through the thickness direction of the plate.
According to the method for chemical testing of nitrogen element, the test result is as follows: the original ferrite contained no nitrogen, while the nitrogen content of the non-ferrite region after nitriding was 0.8wt.%.
According to the microstructure test method of SEM, as in example 1, the test results were: the grains of ferrite and austenite are clearly visible under 500 times electron microscope observation, and it is also observed that the interface of the ferrite area and the non-ferrite area is a strong bond of phase transformation in grain size.
According to the tensile test, the original sample and the sample of the cut nitriding region are subjected to uniaxial tension, as shown in fig. 5, and the test results are as follows: the tensile strength of the metal material in the ferrite region was 435Mpa (broken line corresponding to the original sample), the tensile strength of the metal material in the austenite region was 741Mpa (solid line corresponding to 3g nitriding), and the strength was improved by 1.7 times.
The magnetic performance of the material is observed by adopting the magnetic pole observation sheet, and as a result, under the magnetic pole observation sheet, the magnetic conduction position is grey-white development, but the non-magnetic conduction position is not developed, and as can be seen from figures 8 and 9, the tissue (non-ferrite area) after the solution nitriding is not developed, namely is not magnetic conduction; the structure (ferrite area) under the anti-seepage nitrogen area is grey white development, namely the magnetic conductivity is good;
further according to the soft magnetic B-H measuring instrument test, as shown in FIGS. 10 and 11, the test results are: before nitriding, the magnetic polarization strength of the material is 1.002T, and the maximum magnetic permeability is 208.4; the magnetic polarization strength of the nitrided material is 0.004253T, and the maximum magnetic permeability is 1.167; it was found that the magnetic induction before nitriding was 236 times after nitriding and the magnetic permeability before nitriding was 178 times after nitriding.
(5) Applying the prepared metal material as a motor rotor lamination; wherein the non-ferrite area is used as a magnetic bridge of a motor rotor lamination; the magnetic bridge has no magnetic leakage and no magnetic flux loss; the magnetic bridge is corrosion resistant and high temperature resistant.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (10)

1. A metallic material, comprising: a ferrite region and a non-ferrite region;
the ferrite content in the ferrite area is more than 90%, wherein the main elements of ferrite comprise Fe, cr, mn and Mo, the Cr content is 20-26 wt.%, the Mn content is 2-8 wt.%, and the Mo content is 0.5-2 wt.%;
the content of austenite in the non-ferrite area is more than 70%, and the nitrogen content of the non-ferrite area is 0.4-1.2 wt%;
the boundary between the ferrite area and the non-ferrite area is the combination of ferrite and austenite transformation on grain size.
2. The metal material according to claim 1, wherein the ferrite region is a matrix structure described by a specific region in a Schaeffer stainless steel structure phase diagram, and the specific region means that an equivalent ratio occupied by each element of the ferrite region satisfies the following formula:
Cr equivalent weight ＝Cr％+Mo％+1.5×(Si％+V％)+0.8W％+0.5Nb％+4Ti％+3.5Al％；
Ni Equivalent weight ＝Ni％+Co％+30×(C％+N％)+0.5Mn％+0.33Cu％；
Cr in the ferrite region Equivalent weight More than 20wt.% and less than 30wt.%, ni Equivalent weight Greater than 1wt.% and less than 8wt.%.
3. A metal material according to claim 1 or 2, characterized in that the non-ferritic region is obtained by local solution nitriding of the ferritic region, and that the amount of the remaining elements other than nitrogen in the non-ferritic region does not change before and after nitriding.
4. A metal material according to claim 1, wherein the metal material is a plate material, and the interface between the ferrite region and the non-ferrite region extends through the thickness direction of the plate material.
5. A metal material according to claim 4, wherein the interface between the ferritic region and the non-ferritic region is formed by the localized solution nitriding process.
6. A method for producing a metallic material as defined in any one of claims 1 to 5, wherein said metallic material is obtained by subjecting a plate surface containing only ferrite regions to solution nitriding in selected local regions;
the localized region forms a non-ferritic region after solution nitriding.
7. The method for preparing the metal material according to claim 6, comprising the following steps: firstly, coating a part of area on the surface of a plate only containing a ferrite area with a nitrogen permeation prevention coating or copper plating, then putting the whole coated plate in a high-temperature and high-pressure environment full of nitrogen for solid solution nitriding, taking out and immediately quenching;
and continuously introducing nitrogen with the purity of more than 99.99 percent in the solid solution nitriding process.
8. The method for preparing a metal material according to claim 7, wherein the temperature in the high-temperature and high-pressure environment is 1000 ℃ to 1200 ℃, and the pressure is 0.1MPa to 0.5MPa; the time range of the solid solution nitriding is 0.3 h-4 h.
9. The method of claim 8, wherein the sheet is a rolled sheet having a thickness of 0.1 to 1.5 mm.
10. Use of a metallic material according to any of claims 1-5, characterised in that the metallic material is applied to a rotor lamination of an electric machine;
the non-ferrite area is used as a magnetic bridge of a motor rotor lamination;
the magnetic bridge has no magnetic leakage and no magnetic flux loss.
CN202211146047.XA 2022-09-20 2022-09-20 Metal material and preparation and application thereof Pending CN115627425A (en)

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