A multi-stage relaxation controlled heat treatment apparatus and heat treatment process for metal strip

Abstract

This invention relates to the field of heat treatment technology for thin metal strips, and particularly to a multi-stage relaxation-controlled heat treatment equipment and process for Fe-based and Co-based amorphous alloy strips; it includes a feeding device, a multi-stage relaxation control device, a quenching device, a temperature control device, and a winding device arranged sequentially; the multi-stage relaxation control device includes n+1 sets of high thermal conductivity rollers, where n is an integer greater than or equal to 1, each set of high thermal conductivity rollers includes two high thermal conductivity roller bodies arranged in parallel, and each set of high thermal conductivity rollers is connected to the temperature control device. The multi-stage relaxation-controlled heat treatment equipment for metal strips of this invention can not only accurately control the structural relaxation process of amorphous alloys to obtain the expected performance, but also realize automated continuous and rapid production of amorphous / nanocrystalline strips through programmable control.

Description

Technical Field

[0001] This invention relates to the field of heat treatment technology for thin metal strip materials, and particularly to a multi-stage relaxation-controlled heat treatment equipment and process for Fe-based and Co-based amorphous alloy strips. Background Technology

[0002] Metal heat treatment refers to a process in which pure metals or their alloys are heated to a pre-set temperature in a suitable medium, held at that temperature for a period of time, and then cooled at a certain rate. This process controls the macroscopic properties of the metal by altering its surface or internal microstructure. In the heat treatment of amorphous alloys, the atoms within the alloy rearrange themselves, gradually changing from a completely random, amorphous arrangement to a long-range ordered equilibrium state. The free volume decreases, releasing residual stress within the alloy. This entire transformation process is the structural relaxation process of amorphous alloys. After structural relaxation, Fe-based amorphous alloys exhibit significantly improved resistivity, saturation magnetization, and permeability, while also reducing coercivity and core loss, thus improving their soft magnetic properties.

[0003] There are many controllable parameters in metal heat treatment processes, such as heating rate, heat treatment temperature, holding time, cooling rate, and atmosphere protection. The structure and properties of materials obtained after heat treatment with different process parameters are also different. Annealing Fe-based amorphous alloys at a temperature above the Curie temperature but below the initial crystallization temperature can reduce their relaxation brittleness and release residual stress inside the alloy, thereby reducing coercivity. Appropriate annealing within a temperature range above the initial crystallization temperature but below the second crystallization temperature can cause uniform and fine α-Fe nanocrystals to precipitate in Fe-based amorphous alloys. The interaction coupling between the amorphous phase and the α-Fe nanocrystal phase reduces the average magnetocrystalline anisotropy, thereby improving the saturation magnetization and permeability of the alloy and obtaining excellent soft magnetic properties.

[0004] Currently, commonly used industrial furnace heat treatment equipment cannot precisely control the structural relaxation process of amorphous alloys. Furthermore, the traditional heat treatment process primarily relies on manual labor for tasks such as strip connection, loading, unloading, and furnace entry / exit. In addition, the current industrial practice of winding and stacking strips before heat treatment makes the alloy prone to latent heat of crystallization, and simultaneously generates hard magnetic phase compounds such as Fe3B, which deteriorates the alloy's magnetic properties. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-stage relaxation-controlled heat treatment device and process for metal strips, to solve at least one of the above-mentioned technical problems.

[0006] The technical solution adopted in this invention is as follows:

[0007] A multi-stage relaxation-controlled heat treatment device for metal strip includes a feeding device, a multi-stage relaxation-controlled device, a quenching device, a temperature control device, and a winding device arranged sequentially.

[0008] The multi-stage relaxation control device includes n+1 groups of high thermal conductivity rollers, where n is an integer greater than or equal to 1. Each group of high thermal conductivity rollers includes two high thermal conductivity roller bodies arranged in parallel. Each group of high thermal conductivity rollers is connected to a temperature control device.

[0009] The power shaft of the winding device drives the metal strip to contact the upper and lower surfaces of the high thermal conductivity roller and flow through it quickly, so that the roller-contacting surface and the free surface of the metal strip achieve a uniform heating effect.

[0010] Furthermore, each high thermal conductivity roller includes a high thermal conductivity coating, a heating source core tube, and a high temperature wire. The high thermal conductivity coating is attached to the surface of the heating source core tube, and the high temperature wire is located inside the heating source core tube.

[0011] Furthermore, the high thermal conductivity coating is made of a metalloid element / graphite material, with graphite and the metalloid element bonded together by covalent bonds to form a homogeneous polymorph; the metalloid element in the high thermal conductivity coating is amorphous silicon or crystalline silicon.

[0012] Furthermore, the heating source core tube is composed of alloys and metal oxides.

[0013] Furthermore, the alloy in the heating source core tube is a nickel-chromium-iron alloy, and the metal oxide in the heating source core tube is magnesium oxide.

[0014] Furthermore, the quenching device includes a set of quenching rollers, each consisting of a quenching roller body and a cooling source. The quenching roller body is made of a material with high thermal conductivity, and the cooling source in the quenching roller is selected from one or more of liquid nitrogen and dry ice.

[0015] Furthermore, the temperature control device includes a temperature controller, a relay, and a sheet thermocouple. The temperature controller is connected to the relay, the sheet thermocouple, and a power supply. The relay is connected to a multi-stage relaxation control device and a power supply. The sheet thermocouple is tightly bonded to the surface of the high thermal conductivity roller.

[0016] Furthermore, the winding device includes a winding roller and a drive shaft, with the winding roller mounted on the drive shaft, which is driven by an adjustable speed motor.

[0017] The heat treatment method of the above-mentioned heat treatment equipment includes the following steps:

[0018] The metal strip coil is mounted on the feeding roller of the feeding device. The movable end of the metal strip passes through a multi-stage relaxation control device and a rapid cooling device before being connected to the winding device.

[0019] The power shaft of the winding device drives the metal strip to contact the upper and lower surfaces of each set of high thermal conductivity rollers and flow through them quickly, so that the roller-contacting surface and the free surface of the metal strip achieve a uniform heating effect. It also drives the metal strip to contact the upper and lower surfaces of the quenching rollers and flow through them quickly, so that the roller-contacting surface and the free surface of the metal strip achieve a rapid cooling effect.

[0020] For Fe-Si-B-Nb-Cu-Co metal strips with a thickness of 20~30μm, the surface temperature of multiple sets of high thermal conductivity rollers should be 500~650℃, and the linear velocity of the strip flow should be controlled at 0.05~0.5m / s.

[0021] Furthermore, in the n+1 groups of high thermal conductivity rollers, the surface temperature of the (n+1)th group of high thermal conductivity rollers is greater than that of the nth group of high thermal conductivity rollers, and the surface temperatures of the two high thermal conductivity rollers within the same group are equal. Isothermal annealing above the initial crystallization temperature is beneficial for forming a higher crystallization volume fraction in the amorphous matrix. Annealing at a low temperature below the initial crystallization temperature can effectively release the residual stress inside the alloy, reducing coercivity while maintaining the amorphous structure without crystallization. Then, appropriate annealing at a high temperature above the initial crystallization temperature can cause finer α-Fe nanocrystals to precipitate in the Fe-based amorphous alloy.

[0022] The beneficial effects of adopting the technical solution of the present invention are:

[0023] Compared to commonly used in-furnace heat treatment processes in industry, the multi-stage relaxation-controlled heat treatment equipment for metal strips of this invention can not only precisely control the structural relaxation process of amorphous alloys to achieve the desired performance, but also achieve automated, continuous, and rapid production of amorphous / nanocrystalline strips through programmable control. This offers a strong alternative and optimization to traditional heat treatment processes that currently rely primarily on human labor for strip series connection, loading, unloading, and furnace entry / exit. Furthermore, the current industrial practice of winding and stacking strips before heat treatment easily leads to latent heat of crystallization within the alloy, while simultaneously generating hard magnetic phase compounds such as Fe3B, which deteriorates the alloy's soft magnetic properties. The single-strip flow-type contact heat treatment process of this invention effectively avoids these negative factors. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the multi-stage relaxation-controlled heat treatment equipment for metal strips in this invention.

[0025] Figure 2 Fe, an embodiment of the present invention 72.9 Si 15.8 B 6.9 Nb 3.2 Cu1Co0.2 Differential scanning calorimetry (DSC) curves of quenched amorphous alloys;

[0026] Figure 3 Fe, an embodiment of the present invention 72.9 Si 15.8 B 6.9 Nb 3.2 Cu1Co 0.2 X-ray diffraction (XRD) pattern of amorphous ribbon after heat treatment;

[0027] Figure 4 Fe, an embodiment of the present invention 72.9 Si 15.8 B 6.9 Nb 3.2 Cu1Co 0.2 The change in hysteresis loop (BH) of amorphous ribbon after heat treatment;

[0028] Figure 5 Fe, an embodiment of the present invention 72.9 Si 15.8 B 6.9 Nb 3.2 Cu1Co 0.2 The graph shows the changes in magnetic permeability and coercivity of amorphous ribbons after heat treatment.

[0029] In the figure: 1 feeding device, 11 feeding roller, 12 metal strip, 2 multi-stage relaxation control device, 21 high thermal conductivity roller body, 22 high thermal conductivity coating, 23 heating source core tube, 24 high temperature wire, 3 quenching device, 31 quenching roller, 32 cooling source, 33 quenching roller body, 4 temperature control device, 41 temperature controller, 42 relay, 43 sheet thermocouple, 5 winding device, 51 winding roller, 52 power shaft. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Please see Figure 1The multi-stage relaxation control heat treatment equipment for metal strip 12 in this invention includes a feeding device 1, a multi-stage relaxation control device 2, a rapid cooling device 3, a temperature control device 4, and a winding device 5 arranged sequentially. The feeding device 1 includes a feeding roller 11, on which the metal strip 12 is wound. The movable end of the metal strip 12 is connected to the winding device 5 after passing through the multi-stage relaxation control device 2 and the rapid cooling device 3. The multi-stage relaxation control device 2 includes n+1 sets of high thermal conductivity rollers, where n is an integer greater than or equal to 1. Each set of high thermal conductivity rollers includes two high thermal conductivity roller bodies 21 arranged in parallel. Each set of high thermal conductivity rollers is connected to the temperature control device 4. Multi-stage relaxation control treatment of the metal strip 12 is achieved by adjusting the surface temperature of each set of high thermal conductivity rollers. Multi-stage relaxation control heat treatment can be achieved by precisely controlling the surface temperature of each set of high thermal conductivity rollers. Specifically, each high thermal conductivity roller 21 includes a high thermal conductivity coating 22, a heating source core tube 23, and a high temperature wire 24. The high thermal conductivity coating 22 is attached to the surface of the heating source core tube 23, and the high temperature wire 24 is located inside the heating source core tube 23. The winding device 5 is used to control the flow linear speed of the metal strip 12 and to wind the metal strip 12 after it has been processed by the multi-stage relaxation control device 2 and the rapid cooling device 3. Specifically, in this embodiment, the winding device 5 includes a winding roller 51 and a power shaft 52. The winding roller 51 is sleeved on the power shaft 52, and the power shaft 52 is driven by an adjustable speed motor.

[0032] The drive shaft 52 of the winding device 5 drives the metal strip 12 to contact the upper and lower surfaces of the high thermal conductivity roller 21 and flow through it quickly, so that the roller-contacting surface and the free surface of the metal strip 12 achieve a uniform heating effect. At the same time, the drive shaft 52 of the winding device 5 can drive the metal strip 12 to contact the upper and lower surfaces of the quenching roller 31 and flow through it quickly, so that the roller-contacting surface and the free surface of the metal strip 12 achieve a rapid cooling effect.

[0033] In this embodiment, the high thermal conductivity coating 22 is made of a metalloid element / graphite material. Graphite and the metalloid element are covalently bonded to form a homogeneous polymorph. Specifically, the metalloid element in the high thermal conductivity coating 22 is amorphous silicon or crystalline silicon. The high thermal conductivity coating 22 in this invention is made of a metalloid element / graphite material, which has both high thermal capacity and thermal conductivity as well as wear resistance. This can extend the service life of the high thermal conductivity roller 21 and reduce the cost of use.

[0034] In this embodiment, the heating source core tube 23 is composed of alloys and metal oxides. Specifically, the alloy in the heating source core tube 23 is a nickel-chromium-iron alloy, and the metal oxide in the heating source core tube 23 is magnesium oxide. The heating tube mainly consists of nickel-chromium alloy wire wound on a magnesium oxide rod. The Joule heating effect brought about by the high resistivity of the nickel-chromium alloy is used to raise the temperature by passing electricity. Magnesium oxide is used as an insulating and refractory material to improve the safety of use.

[0035] The rapid cooling device 3 in this embodiment includes a set of rapid cooling rollers 31. The rapid cooling rollers 31 are composed of a cooling source 32 and a rapid cooling roller body 33. The rapid cooling roller body 33 is made of copper, a material with high thermal conductivity. The cooling source 32 in the rapid cooling rollers 31 is selected from one or more of liquid nitrogen and dry ice, depending on the actual needs. Compared with conventional cooling devices, the rapid cooling rollers 31 in this embodiment have a fast cooling speed, resulting in smaller grain sizes growing inside the alloy, which can meet production needs.

[0036] The temperature control device 4 in this embodiment includes a temperature controller 41, a relay 42, and a sheet thermocouple 43. The temperature controller 41 is connected to the relay 42, the sheet thermocouple 43, and a power supply. The relay 42 is connected to the multi-stage relaxation control device 2 and a power supply. The sheet thermocouple 43 is tightly attached to the surface of the high thermal conductivity roller 21, which enables precise control of the temperature of the surface of the high thermal conductivity roller 21.

[0037] The heat treatment method of the above-mentioned heat treatment equipment includes the following steps:

[0038] Twelve coils of metal strip are mounted on the feeding roller 11 of the feeding device 1. The movable end of the metal strip 12 passes through the multi-stage relaxation control device 2 and the rapid cooling device 3 in sequence before being connected to the winding device 5.

[0039] The power shaft 52 of the winding device 5 drives the metal strip 12 to contact the upper and lower surfaces of each group of high thermal conductivity rollers 21 and flow through them quickly, so that the roller-contacting surface and the free surface of the metal strip 12 achieve a uniform heating effect. The metal strip 12 is driven to contact the upper and lower surfaces of the quenching rollers 31 and flow through them quickly, so that the roller-contacting surface and the free surface of the metal strip 12 achieve a rapid cooling effect.

[0040] For metal strip 12 with a thickness of 20~30μm, the surface temperature of multiple sets of high thermal conductivity rollers is 500~650℃, the linear velocity of the strip flow should be controlled at 0.05~0.5m / s, the surface temperature of the (n+1)th set of high thermal conductivity rollers is greater than that of the nth set of high thermal conductivity rollers, and the surface temperatures of the two high thermal conductivity rollers in the same set are equal.

[0041] Fe by means of the device of the present invention 72.9 Si 15.8 B 6.9 Nb 3.2 Cu1Co 0.2 Amorphous alloys undergo multi-stage relaxation-controlled heat treatment, combined with Figure 2 Thermal analysis revealed two exothermic peaks in the DSC curve. The first exothermic peak was due to the precipitation of the α-Fe phase, while the second exothermic peak was related to the precipitation of Fe-based compounds. The onset temperatures (T0) of the two exothermic peaks were... x2 -T x1The large temperature gap of up to 178℃ between these points is beneficial for forming nanostructures with high soft magnetic properties. The heat treatment temperatures should be selected at T... x1 Below (<513℃) or T x1 ~T x2 The temperature range is (513~691℃). Therefore, in this embodiment, the temperatures of multiple sets of high thermal conductivity rollers are set to 500℃ and 610℃ respectively, and the number of roller sets is set to 2. After the alloy strip undergoes multi-stage relaxation-controlled heat treatment at different flow linear velocities (3.3~25.4m / min), it is then transported by... Figure 3 , Figure 4 and Figure 5 Analysis of the experimental results shows that the internal residual stress was gradually released, and a large amount of α-Fe nanocrystalline phase precipitated in the amorphous matrix, which increased the permeability at 10 kHz from 319.29 to 3487.88, decreased the coercivity from 60.21 A / m to 24.85 A / m, and reduced the core loss from 314.40 W / Kg to 84.11 W / Kg, thus significantly improving the soft magnetic properties.

[0042] This invention utilizes multiple sets of high thermal conductivity rollers and quench rollers 31 to perform multi-stage relaxation-controlled heat treatment on metal strips. This not only allows for precise control of the structural relaxation process of amorphous alloys to achieve the desired performance, but also enables automated, continuous, and rapid production, reduces labor costs, and is safe and environmentally friendly. Furthermore, the invention has a simple overall structure and is easy to operate, meeting the needs of large-scale industrial applications and possessing significant implications for practical production.

[0043] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent claim. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A multi-stage relaxation regulation heat treatment method of Fe-Si-B-Nb-Cu-Co metal strip, characterized in that: the heat treatment method uses a device comprising a feeding device, a multi-stage relaxation regulation device, a quenching device, a temperature control device and a winding device arranged in sequence; the multi-stage relaxation regulation device comprises two groups of high thermal conductivity rollers, each group of high thermal conductivity rollers comprises two high thermal conductivity roller bodies and is arranged in parallel, and each group of high thermal conductivity rollers is connected to the temperature control device; the power shaft of the winding device drives the metal strip to contact and quickly flow through the upper end surface and the lower end surface of each high thermal conductivity roller body, so that the roller contact surface and the free surface of the metal strip are uniformly heated; the heat treatment method comprises the following steps: installing the metal strip roll on the feeding roller of the feeding device, and connecting the movable end of the metal strip to the winding device after passing through the multi-stage relaxation regulation device and the quenching device in sequence; the power shaft of the winding device drives the metal strip to contact and quickly flow through the upper end surface and the lower end surface of each group of high thermal conductivity roller bodies, so that the roller contact surface and the free surface of the metal strip are uniformly heated, and the metal strip contacts and quickly flows through the upper end surface and the lower end surface of the quenching roller, so that the roller contact surface and the free surface of the metal strip are quickly cooled; for the Fe-Si-B-Nb-Cu-Co metal strip with a thickness of 20-30 μm, the surface temperature of the first group of high thermal conductivity rollers is 500-513 ℃, the surface temperature of the second group of high thermal conductivity rollers is 600-691 ℃, the surface temperatures of the two high thermal conductivity roller bodies in the same group are equal, and the linear flow speed of the metal strip should be controlled to be 0.05-0.5 m / s. Each high thermal conductivity roller body comprises a high thermal conductivity coating, a heating source core tube and a high temperature wire, the high thermal conductivity coating is attached to the surface of the heating source core tube, and the high temperature wire is located in the heating source core tube. The high thermal conductivity coating is a metalloid element / graphite material, the graphite and the metalloid element are combined by covalent bond to form a homomorphous body, and the metalloid element in the high thermal conductivity coating is amorphous silicon or crystalline silicon. The heating source core tube is composed of an alloy and a metal oxide. The alloy in the heating source core tube is a nickel-chromium-iron alloy, and the metal oxide in the heating source core tube is magnesium oxide. The quenching device comprises a group of quenching rollers, the quenching roller comprises a quenching roller body and a cooling source, the quenching roller body is a high thermal conductivity material, and the cooling source in the quenching roller is selected from one or more of liquid nitrogen and dry ice. The temperature control device comprises a temperature control instrument, a relay and a sheet-shaped thermocouple, the temperature control instrument is connected to the relay, the sheet-shaped thermocouple and a power supply, the relay is connected to the multi-stage relaxation regulation device and the power supply, and the sheet-shaped thermocouple is closely attached to the surface of the high thermal conductivity roller body. The winding device comprises a winding roller and a power shaft, the winding roller is sleeved on the power shaft, and the power shaft is driven by an adjustable speed motor.

2. The multi-stage relaxation control heat treatment method of Fe-Si-B-Nb-Cu-Co metal strip according to claim 1, characterized in that: ​ 3. The multi-stage relaxation control heat treatment method of Fe-Si-B-Nb-Cu-Co metal strip according to claim 2, characterized in that: ​ 4. The multi-stage relaxation control heat treatment method of Fe-Si-B-Nb-Cu-Co metal strip according to claim 2, characterized in that: ​ 5. The multi-stage relaxation control heat treatment method of Fe-Si-B-Nb-Cu-Co metal strip according to claim 4, characterized in that: ​ 6. The multi-stage relaxation control heat treatment method of Fe-Si-B-Nb-Cu-Co metal strip according to claim 1, characterized in that: ​ 7. The multi-stage relaxation-controlled heat treatment method for Fe-Si-B-Nb-Cu-Co metal strip according to claim 1, characterized in that: ​ 8. The multi-stage relaxation control heat treatment method of Fe-Si-B-Nb-Cu-Co metal strip according to claim 1, characterized in that: ​

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