A wide-width Fe-Ni-Mo alloy for use in extremely weak magnetic field shielded rooms, its preparation method and application

Abstract

The application discloses a wide-width Fe-Ni-Mo alloy for an extremely weak magnetic field shielding room and a preparation method and application thereof. Raw materials of the alloy include the following components in percentage by weight: Ni 78.0-78.5 wt%, Mo 4.2-4.7 wt%, Si 0.10-0.15 wt%, Mn 0.10-0.20 wt%, C≤0.01 wt%, S≤0.01 wt%, P≤0.01 wt%, M 0.3-1.0 wt%, and the balance is Fe and inevitable impurities; M is two or three of Cr, Y, V and Nb, and Mo+M≤5.1 wt%. The wide-width Fe-Ni-Mo alloy for the extremely weak magnetic field shielding room takes Fe-Ni-Mo as a matrix, realizes material composition design, production process of excellent and stable mechanical properties and magnetic properties through compounding of different element contents and special heat treatment tooling and methods, and the prepared material has stable high magnetic permeability, low coercive force, high hardness and high strength.

Description

Technical Field

[0001] This invention relates to an alloy, and more particularly to a wide-width Fe-Ni-Mo alloy for use in extremely weak magnetic field shielding rooms, its preparation method, and its application. Background Technology

[0002] Fe-Ni-Mo soft magnetic alloys, also known as permalloy, possess high permeability and low coercivity, making them the best-performing high-permeability alloy materials in the field of magnetic field applications, especially advantageous in magnetic shielding. Fe-Ni-Mo soft magnetic alloys not only have excellent cold-working properties, but also allow for the creation of a wide variety of permalloys with different characteristics through changes in composition, the addition of one or more alloying elements, and process control. Their diversity is unparalleled among soft magnetic materials. These alloys are widely used in the radio electronics industry, precision instruments, and remote control and automatic control systems, primarily for energy conversion and information processing, making them an important material in the national economy.

[0003] Currently, the soft magnetic properties of permalloy include initial permeability, maximum permeability, and coercivity. Magnetic shielding rooms require the lowest possible coercivity and the highest possible initial and maximum permeability. The use of magnetic shielding rooms necessitates sufficient strength and alternating magnetic properties, requiring heat treatment to regulate performance. Therefore, high-nickel-content multi-element alloys are needed to ensure both magnetic and mechanical properties, a challenging task given the difficulty of simultaneously guaranteeing both. Existing permalloy materials include 1J85 and 1J79, whose magnetic properties generally meet the requirements. However, after heat treatment in the fabrication of magnetic shielding rooms, their mechanical properties decrease, leading to deformation and weakened shielding effectiveness. Furthermore, under extremely weak magnetic fields, the magnetic properties of 1J85 and 1J79 are low and unstable, limiting the use of magnetic shielding rooms in such conditions. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a wide-width Fe-Ni-Mo alloy for use in extremely weak magnetic field shielding rooms with excellent mechanical and magnetic properties; another purpose of this invention is to provide a method for preparing and applying this wide-width Fe-Ni-Mo alloy for use in extremely weak magnetic field shielding rooms.

[0005] Technical Solution: The wide-width Fe-Ni-Mo alloy for extremely weak magnetic field shielding rooms described in this invention comprises the following components by weight percentage: Ni 78.0-78.5wt%, Mo 4.2-4.7wt%, Si 0.10-0.15wt%, Mn 0.10-0.20wt%, C≤0.01wt%, S≤0.01wt%, P≤0.01wt%, M 0.3-1.0wt%, with the balance being Fe and unavoidable impurities; wherein M is two or three of Cr, Y, V, and Nb, and Mo+M≤5.1wt%.

[0006] The preparation method of the wide-width Fe-Ni-Mo alloy for extremely weak magnetic field shielding rooms according to the present invention includes the following steps:

[0007] (1) The raw materials are smelted in a vacuum induction furnace and vacuum continuous casting is carried out to obtain flat alloy billets.

[0008] (2) Hot rolling: Hold at 1260-1300℃ for 30-60 minutes and hot roll into hot rolled billet;

[0009] (3) Cold rolling: Multiple cold rolling and intermediate annealing processes are carried out to roll the finished strip into finished strip;

[0010] (4) Cutting and leveling;

[0011] (5) Machining tooling holes;

[0012] (6) Hydrogen-protected heat treatment.

[0013] Preferably, in step (1), the thickness of the flat alloy billet is 100-150 mm and the width is 800-1200 mm.

[0014] Preferably, the thickness of the hot-rolled billet in step (2) is 6-8 mm and the width is 800-1200 mm.

[0015] Preferably, in step (3), the total deformation rate of cold rolling is controlled at 70%-80%, and the cold rolling deformation rate of the finished product is controlled at 66%-70%; the thickness of the finished strip is 1-2 mm, and the width is 800-1200 mm; the intermediate annealing process is as follows: under hydrogen protection, the temperature is raised to 1000-1080℃, and continuous annealing is performed at a speed of 1.5-5.5 m / min.

[0016] Preferably, the cutting specifications in step (4) are 1-2mm in thickness, 800-1200mm in width, and 2000-2100mm in length.

[0017] Preferably, the tooling holes processed in step (5) are designed to be suitable for both splicing and placement of heat treatment process tooling.

[0018] Preferably, the hydrogen protective heat treatment step (6) is as follows: in a hydrogen atmosphere with a dew point of less than -60°C, heat to a temperature of 1160-1200°C, hold for 4-6 hours, then cool to 600-650°C at a cooling rate of 180°C-220°C / h, hold for 1-2 hours, and then cool to below 200°C at a rate of greater than 400°C / h before being removed from the furnace.

[0019] Preferably, the installation process of the material heat treatment in step (6) is to use a special hook to pass through the tooling hole and then place the pieces one by one on the tooling in a hanging manner.

[0020] The application of the wide-width Fe-Ni-Mo alloy for extremely weak magnetic field shielding rooms described in this invention in magnetic shielding rooms.

[0021] Preferably, the magnetically shielded room is a rectangular room.

[0022] Preferably, the rectangular room is a rectangular room composed of four layers of alloy materials, including: a first layer, which is made of heat-treated sheet alloy strips riveted together piece by piece, with an insulating adhesive brushed on the outer surface, and then covered with a second layer, with the riveting points staggered, that is, the riveting position of the second layer is not in the same position as the first layer, and so on, until the fourth layer is completed.

[0023] Invention Principle: This invention uses Fe-Ni-Mo as the matrix and adds two or three of Cr, Y, V, and Nb. Through the compounding of different element contents, it achieves excellent mechanical and magnetic properties through material composition design. While improving magnetic properties, it can also reduce the gas content of the alloy and improve the purity of the alloy by effectively deoxidizing and desulfurizing. The compounds and precipitates are dispersed in the alloy microstructure, effectively enhancing the microstructure of the alloy and refining the grains, thereby improving strength and magnetic properties. As a result, a high-purity alloy material with stable high permeability, low coercivity, high hardness, and high strength is obtained.

[0024] The effects of alloying elements on the alloy in this invention are as follows:

[0025] Nb and Cr elements: Cr, as an austenitizing element, replaces part of Mo in the matrix and can form NiCr solid solution structure with nickel. The pure austenitic microstructure can directly improve the strength and toughness of the alloy material. During the heat treatment of Fe-Ni-Mo alloy, Ni3Fe is easily formed during the cooling stage from 1160-1200℃ to 600-650℃, and long-range ordered changes occur, which significantly reduces the lattice constant and magnetic properties of the alloy material. The addition of Nb and Cr elements slows down the formation of Ni3Fe, resulting in more solid solution structure and reducing the long-range ordered changes of Ni3Fe. The addition of trace amounts of Nb and Cr to this alloy promotes the formation of a solid solution phase of Mo, which coexists with Mo in the matrix. Nb, Cr, and Mo also strengthen the γ-Fe or γ'-Fe phase through solid solution treatment, forming a cubic texture and resulting in a stable multiphase microstructure. This causes the magnetocrystalline anisotropy constant K1 and magnetostriction coefficient λ1 of the alloy to approach zero after heat treatment, thus significantly improving the magnetic permeability of the alloy. Adding different amounts of Nb reacts with the carbon in the alloy to form stable primary or secondary carbides, reducing the supersaturation of the matrix and precipitating Mo2C and Mo6C, which are dispersed at the grain boundaries, thereby improving the stability of the microstructure and ultimately increasing the strength of the alloy.

[0026] Y: Due to its reactive properties, the addition of trace amounts of yttrium can effectively deoxidize and desulfurize during alloy smelting, reduce the formation of interstitial solid solutions in gaseous spaces, and decrease the formation of non-magnetic inclusions such as Al2O3 and TiO2 by impurity elements like Al and Ti. This reduces domain wall pinning of inclusions, thereby lowering the alloy's coercivity. Trace amounts of residual yttrium agglomerate at grain boundaries, strengthening them and increasing the alloy's strength.

[0027] V: Adding V can refine the alloy grains and improve the uniformity of the alloy grains, making the alloy performance more stable. At the same time, the addition of V also brings the technical effect of improving the tensile strength and elongation of the alloy material. V can also form two nanophases with Ni and C in the alloy, and improve the strength of the alloy material by uniformly dispersing and precipitating them.

[0028] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0029] (1) This invention adds two or three of the elements Cr, Y, V and Nb. Through vacuum furnace smelting, the addition of trace alloying elements effectively controls the gas content and purity of the alloy. Through hot rolling, cold rolling and reasonable heat treatment, the hardness, strength and magnetic properties of the alloy are improved.

[0030] (2) The alloy prepared by this invention, after heat treatment, has an initial magnetic permeability μ0 of 100–160 mH / m and a maximum magnetic permeability μ m ≥450mH / m, coercivity Hc: 0.1~0.3A / m, hardness HV0.2: 250~280, tensile strength: 700~1000MPa, elongation 20~35%, grain size: 200~300μm, grain uniformity <15%.

[0031] (3) This invention combines the material composition ratio and process conditions to design a high-purity alloy strip that has both excellent mechanical and magnetic properties and can be used to prepare materials for magnetic shielding rooms; inside the prepared shielding room, the magnetic field in all directions is <5nT. Attached Figure Description

[0032] Figure 1 The image shows the grain size of the alloy material after heat treatment in Example 1 of this invention.

[0033] Figure 2 These are schematic diagrams of the alloy materials used in Embodiments 1 and 3 of the present invention.

[0034] Figure 3 This is a schematic diagram of the alloy material structure in Embodiments 2 and 4 of the present invention. Detailed Implementation

[0035] The technical solution of the present invention will be further described below with reference to the embodiments and accompanying drawings.

[0036] Example 1: The raw materials of the wide-width Fe-Ni-Mo alloy for extremely weak magnetic field shielding rooms described in this invention, by weight percentage, are as follows: Ni 78.2wt%, Mo 4.5wt%, Si 0.1wt%, Mn 0.10wt%, Cr 0.4wt%, Nb 0.04wt%, V 0.08%, C≤0.01wt%, S≤0.01wt%, P≤0.01wt%, with the balance being Fe and unavoidable impurities.

[0037] The preparation method of the above-mentioned iron-nickel alloy includes the following steps:

[0038] (1) The raw materials are smelted in a vacuum induction furnace and vacuum continuous casting to obtain an alloy billet with a thickness of 100mm.

[0039] (2) Hot rolling: At 1300℃, hold for 60 minutes and hot roll into a hot-rolled billet with a thickness of 6mm and a width of 1000mm;

[0040] (3) Cold rolling: Multiple cold rolling and intermediate annealing are carried out. The total deformation rate of cold rolling is controlled at 70%, and the cold rolling deformation rate of finished product is controlled at 70%. The intermediate annealing process is as follows: Under hydrogen protection, the temperature is raised to 1060-1080℃ and continuous annealing is carried out at a speed of 4.5-5.5m / min. The product is rolled into a finished strip with a thickness of 2mm and a width of 1000mm.

[0041] (4) The cutting specifications are: thickness 2mm, width 1000mm, and length 2000mm;

[0042] (5) According to Figure 2 The hole positions of the machining tooling are designed to be suitable for both splicing and placement of heat treatment process tooling.

[0043] The hydrogen-protected heat treatment process described in (6) is as follows: In a hydrogen atmosphere with a dew point less than -60℃, heat to 1160-1200℃, hold for 4-6 hours, then cool to 600-650℃ at a cooling rate of 180℃-220℃ / hour, hold for 1-2 hours, and then cool to below 200℃ at a rate greater than 400℃ / hour before removing from the furnace. The installation process for the heat-treated material is to use special hooks to pass through the tooling holes, and then place each piece on the tooling in a hanging manner.

[0044] Figure 1 Images of the grains of an alloy material after heat treatment.

[0045] Example 2: The raw materials of the wide-width Fe-Ni-Mo alloy for extremely weak magnetic field shielding rooms described in this invention, by weight percentage, are as follows: Ni 78.5wt%, Mo 4.2wt%, Si 0.15wt%, Mn 0.10wt%, Cr 0.3wt%, Nb 0.08wt%, Y 0.08%, C≤0.01wt%, S≤0.01wt%, P≤0.01wt%, with the balance being Fe and unavoidable impurities.

[0046] The preparation method of the above-mentioned iron-nickel alloy includes the following steps:

[0047] (1) The raw materials were smelted in a vacuum induction furnace and vacuum continuous casting was used to obtain an alloy billet with a thickness of 140mm.

[0048] (2) Hot rolling: At 1300℃, hold for 60 minutes and hot roll into a hot-rolled billet with a thickness of 8mm and a width of 1000mm;

[0049] (3) Cold rolling: Multiple cold rolling and intermediate annealing are carried out. The total deformation rate of cold rolling is controlled at 80%, and the cold rolling deformation rate of finished product is controlled at 68%. The intermediate annealing process is as follows: under hydrogen protection, the temperature is raised to 1060-1080℃ and continuous annealing is carried out at a speed of 4.5-5.5m / min to roll into finished strip with a thickness of 2mm and a width of 1200mm.

[0050] (4) The cutting specifications are: thickness 2mm, width 1200mm, and length 2000mm;

[0051] (5) According to Figure 3 The hole positions of the machining tooling are designed to be suitable for both splicing and placement of heat treatment process tooling.

[0052] The hydrogen-protected heat treatment process described in (6) is as follows: In a hydrogen atmosphere with a dew point less than -60℃, heat to 1160-1200℃, hold for 4-6 hours, then cool to 600-650℃ at a cooling rate of 180℃-220℃ / hour, hold for 1-2 hours, and then cool to below 200℃ at a rate greater than 400℃ / hour before removing from the furnace. The installation process for the heat-treated material is to use special hooks to pass through the tooling holes, and then place each piece on the tooling in a hanging manner.

[0053] Example 3: The raw materials for the wide-width Fe-Ni-Mo alloy for extremely weak magnetic field shielding rooms described in this invention, by weight percentage, are as follows: Ni 78.2wt%, Mo 4.5wt%, Si 0.1wt%, Mn 0.10wt%, Cr 0.4wt%, Nb 0.04wt%, V 0.08%, C≤0.01wt%, S≤0.01wt%, P≤0.01wt%, with the balance being Fe and unavoidable impurities.

[0054] The preparation method of the above-mentioned iron-nickel alloy includes the following steps:

[0055] (1) The raw materials are smelted in a vacuum induction furnace and vacuum continuous casting to obtain an alloy billet with a thickness of 100mm.

[0056] (2) Hot rolling: At 1300℃, hold for 60 minutes and hot roll into a hot-rolled billet with a thickness of 6mm and a width of 800mm;

[0057] (3) Cold rolling: Multiple cold rolling and intermediate annealing are carried out. The total deformation rate of cold rolling is controlled at 70%, and the cold rolling deformation rate of finished product is controlled at 66%. The intermediate annealing process is as follows: under hydrogen protection, the temperature is raised to 1000-1020℃ and continuous annealing is carried out at a speed of 1.5-3.5m / min. The product is rolled into a finished strip with a thickness of 1mm and a width of 800mm.

[0058] (4) The cutting specifications are: thickness 1mm, width 800mm, and length 2000mm;

[0059] (5) According to Figure 2 The hole positions of the machining tooling are designed to be suitable for both splicing and placement of heat treatment process tooling.

[0060] The hydrogen-protected heat treatment process described in (6) is as follows: In a hydrogen atmosphere with a dew point less than -60℃, heat to 1160-1200℃, hold for 4-6 hours, then cool to 600-650℃ at a cooling rate of 180℃-220℃ / hour, hold for 1-2 hours, and then cool to below 200℃ at a rate greater than 400℃ / hour before removing from the furnace. The installation process for the heat-treated material is to use special hooks to pass through the tooling holes, and then place each piece on the tooling in a hanging manner.

[0061] Example 4: The raw materials for the wide-width Fe-Ni-Mo alloy for extremely weak magnetic field shielding rooms described in this invention, by weight percentage, are as follows: Ni 78.2wt%, Mo 4.5wt%, Si 0.1wt%, Mn 0.10wt%, Cr 0.4wt%, Nb 0.04wt%, V 0.08%, C≤0.01wt%, S≤0.01wt%, P≤0.01wt%, with the balance being Fe and unavoidable impurities.

[0062] The preparation method of the above-mentioned iron-nickel alloy includes the following steps:

[0063] (1) The raw materials are smelted in a vacuum induction furnace and vacuum continuous casting to obtain an alloy billet with a thickness of 150mm.

[0064] (2) Hot rolling: Hold at 1300℃ for 60 minutes and hot roll into a hot-rolled billet with a thickness of 8mm and a width of 1200mm;

[0065] (3) Cold rolling: Multiple cold rolling and intermediate annealing are carried out. The total deformation rate of cold rolling is controlled at 80%, and the cold rolling deformation rate of finished product is controlled at 70%. The intermediate annealing process is as follows: Under hydrogen protection, the temperature is raised to 1060-1080℃ and continuous annealing is carried out at a speed of 4.5-5.5m / min. The product is rolled into a finished strip with a thickness of 2mm and a width of 1200mm.

[0066] (4) The cutting specifications are: thickness 2mm, width 1200mm, and length 2100mm;

[0067] (5) According to Figure 3 The hole positions of the machining tooling are designed to be suitable for both splicing and placement of heat treatment process tooling.

[0068] The hydrogen-protected heat treatment process described in (6) is as follows: In a hydrogen atmosphere with a dew point less than -60℃, heat to 1160-1200℃, hold for 4-6 hours, then cool to 600-650℃ at a cooling rate of 180℃-220℃ / hour, hold for 1-2 hours, and then cool to below 200℃ at a rate greater than 400℃ / hour before removing from the furnace. The installation process for the heat-treated material is to use special hooks to pass through the tooling holes, and then place each piece on the tooling in a hanging manner.

[0069] Comparative Example 1: Conventional permalloy material 1J85, by weight percentage, includes the following components: Ni 80wt%, Mo 5.0wt%, Si 0.12wt%, Mn 0.50wt%, C≤0.01wt%, S≤0.01wt%, P≤0.01wt%, with the balance being Fe and unavoidable impurities.

[0070] The preparation method of the above-mentioned iron-nickel alloy includes the following steps:

[0071] (1) The raw materials are smelted in a vacuum induction furnace to obtain alloy ingots;

[0072] (2) Forging: Hold at 1280℃ for 1.5 hours to forge a forging billet with a thickness of 90mm and a width of 500mm;

[0073] (3) Hot rolling: Hold at 1260℃ for 60 minutes and hot roll into a hot-rolled billet with a thickness of 5mm and a width of 500mm;

[0074] (4) Cold rolling: Multiple cold rolling and intermediate annealing are carried out. The total deformation rate of cold rolling is controlled at 70%, and the cold rolling deformation rate of finished product is controlled at 70%. The intermediate annealing process is as follows: Under hydrogen protection, the temperature is raised to 950-1080℃ and continuous annealing is carried out at a speed of 1.5-5.5m / min. The product is rolled into a finished strip with a thickness of 2mm and a width of 500mm.

[0075] (5) Obtain strip with good plate shape by tension straightening, and heat it to 630℃ under inert gas protection, and perform stress relief annealing at a speed of 15m / min.

[0076] The alloy materials from Examples 1, 2, and Comparative Example 1 were combined into a magnetic shielding room according to the circular magnetic shielding room combination method described in this invention. The specific combination method is as follows: a rectangular room is formed by stacking four layers of alloy materials. The first layer is made by riveting heat-treated sheet alloy strips piece by piece, with an insulating adhesive applied to the outer surface. A second layer is then placed on top, with the riveting joints staggered, meaning the riveting position of the second layer is not the same as the first layer. This process continues until the fourth layer is completed. Experimental results show that this invention effectively controls the gas content and purity of the alloy through vacuum furnace smelting, vacuum continuous casting, and the addition of trace alloying elements. Through hot rolling, cold rolling, and reasonable hole design and heat treatment, the hardness, strength, and magnetic properties of the alloy are improved. Inside the prepared shielding room, the magnetic field in all directions is <5nT.

[0077] Table 1. Oxygen, hydrogen, and nitrogen content and material purity of alloy samples after heat treatment.

[0078] Oxygen content ppm Hydrogen content (ppm) Nitrogen content (ppm) Example 1 13 15 14 Example 2 8 10 13 Comparative Example 1 21 28 43

[0079] Table 2 Magnetic properties of finished alloy samples after heat treatment

[0080]

[0081] Table 3 Mechanical properties of finished alloy samples after heat treatment

[0082] Tensile strength (MPa) elongation % Hardness Hv0.2 Average grain size (μm) Example 1 906 30 297 270 Example 2 824 39 289 256 Comparative Example 1 589 26 245 210

[0083] Table 4. Magnetic shielding experimental data for the magnetic shielding room.

[0084] The average magnetic field nT in all directions inside the shielded room Example 1 4 Example 2 3 Comparative Example 1 23

Claims

1. A wide-width Fe-Ni-Mo alloy for an extremely weak magnetic field shield room, characterized by, The raw material of the alloy comprises the following components in percentage by weight: Ni 78.0-78.5wt%, Mo 4.2-4.7wt%, Si 0.10-0.15wt%, Mn 0.10-0.20wt%, C≤0.01wt%, S≤0.01wt%, P≤0.01wt%, M 0.3~1.0wt%, the balance being Fe and inevitable impurities; the M is Cr, V and Nb, or the M is Cr, Y and Nb; Mo+M≤5.1wt%. The preparation method of the wide-width Fe-Ni-Mo alloy for the extremely weak magnetic field shielding room comprises the following steps: (1) The raw material is smelted by a vacuum induction furnace and vacuum continuous casting to obtain a flat alloy casting blank; (2) Hot rolling: hot rolling into a hot-rolled blank at 1260-1300℃ for 30-60 min; (3) Cold rolling: multi-pass cold rolling and intermediate annealing treatment to roll into finished strip; (4) Shearing and flattening; (5) Machining of tooling hole positions; (6) Hydrogen protection heat treatment; In the step (3), the total deformation rate of the cold rolling is controlled to be 70%-80%, and the finished cold rolling deformation rate is controlled to be 66%-70%; the intermediate annealing treatment is as follows: under the condition of hydrogen protection, heating to 1000-1080℃, and continuously annealing at a speed of 1.5-5.5 m / min; In the step (6), the hydrogen protection heat treatment is as follows: heating to a temperature of 1160-1200℃ in a hydrogen atmosphere with a dew point less than -60℃, and then heat preservation for 4-6 h, and then cooling to 600-650℃ at a cooling speed of 180-220℃ / h, and then heat preservation for 1-2 h, and then cooling to below 200℃ at a speed greater than 400℃ / h and discharging.

2. A method of producing a wide Fe-Ni-Mo alloy for use in a very weak magnetic field shield room according to claim 1, characterized by, Comprise the following steps: (1) The raw material is smelted by a vacuum induction furnace and vacuum continuous casting to obtain a flat alloy casting blank; (2) Hot rolling: hot rolling into a hot-rolled blank at 1260-1300℃ for 30-60 min; (3) Cold rolling: multi-pass cold rolling and intermediate annealing treatment to roll into finished strip; (4) Shearing and flattening; (5) Machining of tooling hole positions; (6) Hydrogen protection heat treatment.

3. The method of producing a wide Fe-Ni-Mo alloy for a very weak magnetic field shielding room according to claim 2, characterized by, In the step (1), the thickness of the flat alloy casting blank is 100-150 mm, and the width is 800-1200 mm.

4. The method of claim 2, wherein the wide-width Fe-Ni-Mo alloy for the extremely low field shield room is prepared by the steps of: preparing a master alloy by mixing Fe, Ni, and Mo in a predetermined ratio; and casting the master alloy into a predetermined shape. In the step (2), the thickness of the hot-rolled blank is 6-8 mm, and the width is 800-1200 mm.

5. The method of claim 2, wherein the wide-width Fe-Ni-Mo alloy for the extremely low field shield room is prepared by the steps of: preparing a master alloy by mixing Fe, Ni, and Mo in a predetermined ratio; and casting the master alloy into a predetermined shape. In the step (3), the thickness of the finished strip is 1-2 mm, and the width is 800-1200 mm.

6. The method of claim 2, wherein the wide-width Fe-Ni-Mo alloy for the extremely low field shield room is prepared by the steps of: preparing a master alloy by mixing Fe, Ni, and Mo in a predetermined ratio; and casting the master alloy into a predetermined shape. In the step (4), the shearing specification thickness is 1-2 mm, the width is 800-1200 mm, and the length is 2000-2100 mm.

7. The wide-width Fe-Ni-Mo alloy for the extremely weak magnetic field shielding room of claim 1 is applied in a magnetic shielding room.

8. Use according to claim 7, characterized in that, The magnetic shielding room is a rectangular room.

9. Use according to claim 8, characterized in that, The rectangular house is composed of four layers of alloy material superposition, including: the first layer is riveted by sheet-shaped alloy strip material after heat treatment, the outer surface is brushed with insulating adhesive, and then the second layer is covered, the riveting position of the second layer is staggered with the first time, and so on until the fourth layer is completed.

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