Preparation method of high-strength non-magnetic round steel for large submarine cable armor

Abstract

The application discloses a preparation method of high-strength non-magnetic round steel for large submarine cable armor, which comprises the following steps: S1, smelting and blank preparation: adopting a converter+LF furnace+slab continuous casting mode to obtain Fe-Mn-Al-C series AM05 non-magnetic steel continuous casting slab with a thickness of 220 mm; S2, blooming rolling: after the continuous casting slab obtained in the step S1 is heated to 1220-1240 DEG C in a heating furnace, blooming rolling is carried out; S3, cutting: using tongs, the slab obtained in the step S2 is placed on a cutting machine rack and tightly pressed; S4, hot rolling: after the cut square billet is rolled in a high-speed wire rod production line, it is concentrated into a heating furnace according to batches, and passes through a rough rolling non-punching unit, a medium rolling punching unit, pre-precision rolling, precision rolling and a reducing sizing unit; and S5, wire drawing: the diameter φ6.5-φ8mm hot-rolled round strip drawing material is treated by skin film and dried on a wire drawing machine to carry out single or multi-pass drawing.

Description

Technical Field

[0001] This invention relates to the field of submarine cable technology, and in particular to a method for preparing high-strength non-magnetic round steel for armoring large submarine cables. Background Technology

[0002] Adding an armor layer to large power transmission cables enhances their tensile and compressive strength, providing mechanical protection and extending their service life. It also offers good resistance to low-frequency interference and magnetic shielding, effectively reducing the AC resistance of the cable conductor and shield, thus providing shielding, protection, and improved current-carrying capacity. However, currently used non-magnetic materials like copper and aluminum for the outer armor layer have excellent magnetic properties but low strength and are expensive. Austenitic stainless steel generates magnetism during cold drawing, but its strength is low and nonexistent. For offshore wind power and island connection projects, which often involve deep-sea laying, the increased weight of submarine cables means that ordinary non-magnetic armored steel wires cannot meet the high tension requirements of the laying process.

[0003] High-manganese non-magnetic steel is a high-aluminum, high-manganese alloy steel with extremely low magnetic properties. Its main components are iron, manganese, aluminum, vanadium, and other elements. Its magnetic permeability is much lower than that of ordinary steel, giving it excellent magnetic shielding performance and effectively blocking the influence of external magnetic fields on equipment. It not only has high strength and hardness but also excellent corrosion resistance and heat resistance, making it a highly cost-effective choice for armoring steel with excellent mechanical properties.

[0004] However, the high Mn and Al content in Fe-Mn-Al-C non-magnetic steel makes the continuous casting process of square billets extremely difficult, thus limiting the production of Fe-Mn-Al-C non-magnetic round steel. In the prior art, invention patent application number 202410192156.8 discloses a method for preparing zero-magnetic steel bars for special non-magnetic concrete structures. Zero-magnetic steel bars produced by this method possess multiple advantages, including zero magnetism, high strength, good ductility, corrosion resistance, and shock resistance, and are reasonably priced, making them suitable for industrial production and large-scale use. However, this method still obtains Fe-Mn-Al-C zero-magnetic steel bars through ingot casting, which is complex, costly, inefficient, and the ingot casting method cannot effectively guarantee the steel's performance. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing high-strength non-magnetic round steel for armoring large submarine cables.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for preparing high-strength non-magnetic round steel for armoring large submarine cables includes the following steps:

[0008] S1. Smelting and billet preparation: Using a converter + LF furnace + slab continuous casting method, a Fe-Mn-Al-C system AM05 non-magnetic steel continuous casting slab with a thickness of 220mm is obtained.

[0009] S2. Initial rolling: The continuous casting slab obtained in step S1 is heated to 1220-1240℃ in a heating furnace and then rolled. The initial rolling thickness is controlled at 140-160mm to obtain a slab with an initial rolling thickness of 140-160mm.

[0010] S3. Cutting: Use clamps to place the slab obtained in step S2 on the cutting machine stand and tighten it. According to the width of the slab after initial rolling, take N points at equal intervals of 150-160mm on each of the two end faces of the slab. Adjust the position of the flame cutting gun and control the kerf width to ≤8mm. The cut square billet with a width of 145-155mm is then cut off. After the billet is cut off, deburring is performed.

[0011] S4. Hot rolling: The cut square billets are rolled on a high-speed wire rod production line, and then fed into a heating furnace in batches. After being heated to 1180-1220℃, they are taken out of the furnace and rolled into hot-rolled round bar wire rods with a diameter of φ6.5-φ8mm through a roughing mill without holes, a medium mill with holes, a pre-finishing mill, a finishing mill, and a sizing mill.

[0012] S5. Wire drawing: The hot-rolled round bar wire with a diameter of φ6.5~φ8mm is treated with a coating and dried. It is then drawn in one or more passes on a wire drawing machine. After annealing, grinding, polishing and galvanizing, AM05 non-magnetic round steel with a diameter of φ3~φ6mm is finally obtained.

[0013] The AM05 non-magnetic round steel obtained in step S5 has the following composition by weight percentage: C: 0.05-0.20%, Si: 0.15-0.30%, Mn: 18-25%, Al: 1.0-2.0%, Nb+V+Ti: 0.04-0.08%, B+Zn: 0.0020-0.0050%, P≤0.045%, S≤0.03%, with the remainder being Fe and unavoidable impurities.

[0014] In step S3, the number of cutting points N of the flame cutting gun is determined based on the width of the slab after initial rolling and the cutting spacing. N = slab width / cutting spacing, where N is an integer.

[0015] In step S3, the cutting machine is a flame cutting machine for processing flat steel rectangular billets. The cutting temperature of the billet is 20-200℃. The energy medium used for cutting is cutting oxygen, cutting gas, or industrial purified water. The cutting kerf is ≤8mm and the surface roughness is ≤2mm.

[0016] In step S4, during the rolling process on the high-speed wire rod production line, the rolling roll gap, material shape, and speed are controlled according to conventional specifications. The wire drawing temperature is controlled at 850℃, and the air-cooling section adopts a front-middle section rapid cooling + rear section air cooling control method.

[0017] The beneficial effects of this invention are:

[0018] 1. The high-strength non-magnetic round steel AM05 produced by this invention, after being drawn, has physical properties that meet the requirements of yield strength Rp0.2≥500MPa, tensile strength Rm≥700MPa, and elongation A / %≥35%. It has excellent mechanical properties and plays a role in protecting and extending service life.

[0019] 2. The high-strength non-magnetic round steel AM05 produced by this invention, after drawing, has a magnetic permeability of 1.000~1.002; a resistivity of 0.68Ω.m at room temperature and 0.75Ω.m at 100℃; an austenite content of ≥99.9% and a grain size of 11.5, and does not demagnetize, thus achieving non-magnetic control.

[0020] 3. This invention improves the chemical corrosion resistance of non-magnetic round steel through drawing, annealing, grinding, polishing, and galvanizing, and is cost-effective, making it suitable for industrial production and large-scale use. Attached Figure Description

[0021] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0022] Figure 1 This is a metallographic diagram of the φ6mm non-magnetic round steel wire for armored cables produced by this invention.

[0023] Figure 2 This is a metallographic diagram of the AM05 high-strength non-magnetic round steel with a diameter of φ3mm produced by the present invention for armored cables. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0025] Example 1

[0026] A method for preparing high-strength non-magnetic round steel for armoring large submarine cables includes the following steps:

[0027] S1. Smelting and billet preparation: Using a converter + LF furnace + slab continuous casting method, a Fe-Mn-Al-C system AM05 non-magnetic steel continuous casting slab with a thickness of 220mm is obtained;

[0028] S2. Initial rolling: The continuous casting slab obtained in step S1 is heated to 1220℃ in a heating furnace and then rolled. The initial rolling thickness is controlled at 140mm to obtain a slab with an initial rolling thickness of 140mm.

[0029] S3. Cutting: Use clamps to place the slab obtained in step S2 on the cutting machine stand and tighten it. According to the width of the slab after initial rolling, take N points at 150mm intervals on each of the two end faces of the slab. Adjust the position of the flame cutting gun and control the kerf width to ≤8mm. The cut square billet has a width of 145mm. After the billet is cut off, deburring is performed.

[0030] S4. Hot rolling: The cut square billets are rolled on a high-speed wire rod production line, and then fed into a heating furnace in batches. After being heated to 1180℃, they are taken out of the furnace and rolled into hot-rolled round bar wire with a diameter of φ6.5mm through a roughing mill without holes, a medium mill with holes, a pre-finishing mill, a finishing mill, and a sizing mill.

[0031] S5. Wire drawing: The hot-rolled round bar wire with a diameter of φ6.5mm is treated with a film and dried. It is then drawn in one or more passes on a wire drawing machine. After annealing, grinding, polishing and galvanizing, AM05 non-magnetic round steel with a diameter of φ3mm is finally obtained.

[0032] The AM05 non-magnetic round steel obtained in step S5 has the following composition by weight percentage: C: 0.05%, Si: 0.15%, Mn: 18%, Al: 1.0%, Nb+V+Ti: 0.04%, B+Zn: 0.0020%, P≤0.045%, S≤0.03%, with the remainder being Fe and unavoidable impurities.

[0033] In step S3, the number of cutting points N of the flame cutting gun is determined based on the width of the slab after initial rolling and the cutting spacing. N = slab width / cutting spacing, where N is an integer.

[0034] In step S3, the cutting machine is a flame cutting machine for processing flat steel rectangular billets. The cutting temperature of the billet is 20°C. The energy medium used for cutting is cutting oxygen, cutting gas, or industrial purified water. The cutting kerf is ≤8mm and the surface roughness is ≤2mm.

[0035] In step S4, during the rolling process on the high-speed wire rod production line, the rolling roll gap, material shape, and speed are controlled according to conventional specifications. The wire drawing temperature is controlled at 850℃, and the air-cooling section adopts a front-middle section rapid cooling + rear section air cooling control method.

[0036] Example 2

[0037] A method for preparing high-strength non-magnetic round steel for armoring large submarine cables includes the following steps:

[0038] S1. Smelting and billet preparation: Using a converter + LF furnace + slab continuous casting method, a Fe-Mn-Al-C system AM05 non-magnetic steel continuous casting slab with a thickness of 220mm is obtained.

[0039] S2. Initial rolling: The continuous casting slab obtained in step S1 is heated to 1240℃ in a heating furnace and then rolled. The initial rolling thickness is controlled at 160mm to obtain a slab with an initial rolling thickness of 160mm.

[0040] S3. Cutting: Use clamps to place the slab obtained in step S2 on the cutting machine stand and tighten it. According to the width of the slab after initial rolling, take N points at equal intervals of 160mm on each of the two end faces of the slab. Adjust the position of the flame cutting gun and control the kerf width to ≤8mm. The cut square billet has a width of 155mm. After the billet is cut off, deburring is performed.

[0041] S4. Hot rolling: The cut square billets are rolled on a high-speed wire rod production line, and then fed into a heating furnace in batches. After being heated to 1220℃, they are taken out of the furnace and rolled into hot-rolled round bar wire with a diameter of φ8mm through roughing mill without holes, intermediate mill with holes, pre-finishing mill, finishing mill and sizing mill.

[0042] S5. Wire drawing: The hot-rolled round bar wire with a diameter of φ8mm is treated with a film and dried. It is then drawn in one or more passes on a wire drawing machine. After annealing, grinding, polishing and galvanizing, AM05 non-magnetic round steel with a diameter of φ6mm is finally obtained.

[0043] The AM05 non-magnetic round steel obtained in step S5 has the following composition by weight percentage: C: 0.20%, Si: 0.30%, Mn: 25%, Al: 2.0%, Nb+V+Ti: 0.08%, B+Zn: 0.0050%, P≤0.045%, S≤0.03%, with the remainder being Fe and unavoidable impurities.

[0044] In step S3, the number of cutting points N of the flame cutting gun is determined based on the width of the slab after initial rolling and the cutting spacing. N = slab width / cutting spacing, where N is an integer.

[0045] In step S3, the cutting machine is a flame cutting machine for processing flat steel rectangular billets. The cutting temperature of the billet is 200℃. The energy medium used for cutting is cutting oxygen, cutting gas, or industrial purified water. The cutting kerf is ≤8mm and the surface roughness is ≤2mm.

[0046] In step S4, during the rolling process on the high-speed wire rod production line, the rolling roll gap, material shape, and speed are controlled according to conventional specifications. The wire drawing temperature is controlled at 850℃, and the air-cooling section adopts a front-middle section rapid cooling + rear section air cooling control method.

[0047] Example 3

[0048] A method for preparing high-strength non-magnetic round steel for armoring large submarine cables includes the following steps:

[0049] S1, Smelting and Billet Preparation: Blast furnace molten iron pretreated with dephosphorization is added to the AOD converter. Coke and lime are added, followed by top-side oxygen blowing. After the main decarburization stage, high-carbon ferromanganese is added at a rate of 65 kg / t steel to achieve primary manganese alloying. After primary manganese alloying, oxygen is blown first, and then the argon-oxygen ratio is adjusted for deep decarburization until the carbon content is controlled at 0.14%. After the decarburization stage, electrolytic manganese at a rate of 195 kg / t steel is added to achieve secondary manganese alloying. During the AOD furnace reduction stage, 20 kg / t aluminum granules are added for aluminum alloying while the composition is finely adjusted. After stirring evenly, the steel is tapped. The molten steel after AOD smelting is hoisted to the LF furnace for heating and desulfurization, and the composition is finely adjusted while 1.2 kg / t ferrovanadium is added for vanadium alloying. The refined molten iron is hoisted to the continuous casting platform for casting. The tundish temperature is 1445℃, and the casting speed is 0.7 m / min, resulting in a 220 mm continuous casting slab.

[0050] S2, billet rolling: The 220mm thick continuous casting slab is heated to 1225℃ in a heating furnace and rolled to 150×1540×8900mm.

[0051] S3, Cutting: Use clamps to place the rolled slab on the cutting machine stand and tighten it. According to the width of the slab after initial rolling, take 8 points at equal intervals of 160mm on each of the two end faces of the slab. Adjust the position of the flame cutting gun and control the kerf width to 8mm. The cut slab is 152mm wide. After the slab is cut off, deburring is performed.

[0052] S4, hot rolling: The cut square billet is rolled on a high-speed wire rod production line, and then fed into a heating furnace in batches. After being heated to 1220℃, it is taken out of the furnace and rolled into hot-rolled round bar wire with a diameter of φ8mm through roughing mill without holes, intermediate mill with holes, pre-finishing mill, finishing mill and sizing mill.

[0053] S5, Wire drawing: The hot-rolled round bar wire with a diameter of φ8mm is treated with a film and dried, and then drawn in one or more passes on a wire drawing machine. After annealing, grinding, polishing and galvanizing, the final product with a diameter of φ6mm is obtained.

[0054] The high-strength non-magnetic round steel AM05 that meets the requirements is prepared by the above steps. The chemical composition, expressed as a weight percentage, is shown in the table below:

[0055] .

[0056] The number of cutting points N of the flame cutting gun in step S3 is determined according to the width of the slab after initial rolling and the cutting spacing: N = slab width / cutting spacing (N is an integer). In this example, the slab width is 1280mm, the cutting spacing is 160mm, and the number of cutting points = 1280 / 160 = 8.

[0057] The cutting machine used in step S3 is a flame cutting machine for processing flat steel rectangular billets. The cutting temperature of the billet is 25°C. The energy medium used for cutting is cutting oxygen. The cutting kerf is 8mm and the surface roughness is ≤2mm.

[0058] In step S4, the rolling roll gap, material shape, and speed are controlled according to conventional specifications during the high-speed wire rod production line rolling process. The wire drawing temperature is controlled at 850℃, and the air cooling section adopts a front-middle section rapid cooling + rear section air cooling control method.

[0059] The mechanical properties of AM05 high-strength non-magnetic round steel produced by this method, after being drawn to 6mm, are shown in the table below:

[0060]

[0061] With an average tensile strength Rm of 729.15 MPa and an elongation A / % of 39.06%, it exhibits excellent mechanical properties, playing a role in protecting and extending service life.

[0062] The non-magnetic round steel AM05 produced by this method, after being drawn to 6mm, has the following permeability test results:

[0063]

[0064] The resistivity of AM05 non-magnetic round steel produced by this method, after being drawn to 6mm, is shown in the table below:

[0065]

[0066] like Figure 1 The image shown is a metallographic diagram of a 6mm diameter non-magnetic round steel wire for armored cables produced by this invention. The austenite content is ≥99.9%, the grain size is 11.5, and it does not demagnetize, thus achieving non-magnetic control.

[0067] After being drawn, annealed, ground, polished, and galvanized, the non-magnetic round steel has improved chemical corrosion resistance and is reasonably priced, making it suitable for industrial production and large-scale use.

[0068] Example 4

[0069] A method for preparing high-strength non-magnetic round steel for armoring large submarine cables includes the following steps:

[0070] S1, Smelting and Billet Preparation: Blast furnace molten iron pretreated with dephosphorization is added to the AOD converter. Coke and lime are added, followed by top-side oxygen blowing. After the main decarburization stage, high-carbon ferromanganese is added at a rate of 60 kg / t steel to achieve primary manganese alloying. After primary manganese alloying, oxygen is blown first, and then the argon-oxygen ratio is adjusted for deep decarburization until the carbon content is controlled at 0.15%. After the decarburization stage, electrolytic manganese at a rate of 200 kg / t steel is added to achieve secondary manganese alloying. During the AOD furnace reduction stage, 18 kg / t aluminum granules are added for aluminum alloying while the composition is finely adjusted. After stirring evenly, the steel is tapped. The molten steel after AOD smelting is hoisted to the LF furnace for heating and desulfurization, and the composition is finely adjusted while 1.1 kg / t ferrovanadium is added for vanadium alloying. The refined molten iron is hoisted to the continuous casting platform for casting. The tundish temperature is 1440℃, and the casting speed is 0.75 m / min, resulting in a 220 mm continuous casting slab.

[0071] S2, billet rolling: The 220mm thick continuous casting slab is heated to 1225℃ in a heating furnace and rolled to 140×1200×9100mm.

[0072] S3, Cutting: Use clamps to place the 140mm thick slab on the cutting machine stand and tighten it. According to the width of the slab after initial rolling, take 8 points at 150mm intervals on each of the two end faces of the slab. Adjust the position of the flame cutting gun and control the kerf width to 5mm. The resulting square billet is 145mm wide. After the billet is cut off, deburring is performed.

[0073] S4, Hot rolling: The 140×145mm square billet after cutting is rolled on a high-speed wire rod production line, and then fed into a heating furnace in batches. After being heated to 1215℃, it is taken out of the furnace and rolled into hot rolled round bar wire with a diameter of φ6.5mm through a roughing mill without holes, a medium rolling mill with holes, a pre-finishing mill, a finishing mill and a sizing mill.

[0074] S5, Wire drawing: The hot-rolled round bar wire with a diameter of φ6.5mm is treated with a film and dried, and then drawn in one or more passes on a wire drawing machine. After annealing, grinding, polishing and galvanizing, the final product with a diameter of φ3mm is obtained.

[0075] The AM05 non-magnetic steel that meets the requirements is prepared by the above steps. The chemical composition of the AM05 non-magnetic round steel, expressed as a weight percentage, is shown in the table below:

[0076]

[0077] The number of cutting points N of the flame cutting gun in step S3 is determined according to the width of the slab after initial rolling and the cutting spacing: N = slab width / cutting spacing (N is an integer). In this example, the slab width is 1200mm, the cutting spacing is 150mm, and the number of cutting points = 1280 / 160 = 8.

[0078] The cutting machine used in step S3 is a flame cutting machine for processing flat steel rectangular billets. The cutting temperature of the billet is 185℃. The energy medium used for cutting is cutting oxygen. The cutting kerf is 5mm and the surface roughness is ≤2mm.

[0079] In step S4, the rolling roll gap, material shape, and speed are controlled according to conventional specifications during the high-speed wire rod production line rolling process. The wire drawing temperature is controlled at 865℃, and the air cooling section adopts a front-middle section rapid cooling + rear section air cooling control method.

[0080] The mechanical properties of AM05 non-magnetic round steel produced by this method, after being drawn to 3mm, are shown in the table below:

[0081]

[0082] With an average tensile strength Rm of 1529.30 MPa and an elongation A / % of 39.84%, it exhibits excellent mechanical properties, playing a role in protecting and extending service life.

[0083] The non-magnetic round steel AM05 produced by this method, after being drawn to 3mm, has the following permeability test results:

[0084]

[0085] The resistivity of AM05 non-magnetic round steel produced by this method, after being drawn to 3mm, is shown in the table below:

[0086]

[0087] like Figure 2 The image shown is a metallographic diagram of a 3mm thick non-magnetic round steel wire for armored cables produced by this invention. The austenite content is ≥99.9%, the grain size is 12.5, and it does not demagnetize, thus achieving non-magnetic control.

[0088] After being drawn, annealed, ground, polished, and galvanized, the non-magnetic round steel has improved chemical corrosion resistance and is reasonably priced, making it suitable for industrial production and large-scale use.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing a high-strength non-magnetic round steel for large submarine cable armor, characterized by, Comprise the following steps: S1, smelting billet: using converter + LF furnace + slab continuous casting mode, get the thickness of 220mm Fe-Mn-Al-C system AM05 non-magnetic steel continuous casting slab; S2, breakdown rolling: the continuous casting slab obtained in step S1 is heated to 1220-1240℃ in a heating furnace, and then subjected to breakdown rolling, and the thickness is controlled to 140-160mm, and a slab with a rough rolling thickness of 140-160mm is obtained; S3, cutting: using tongs to place the slab obtained in step S2 on the cutting machine rack and clamp tightly, according to the slab width after rough rolling, taking N equidistant 150-160mm points on the two end faces of the slab, adjusting the gun position of the flame cutting gun, controlling the slit width ≤8mm, cutting the square billet with a width of 145-155mm, and after cutting, the square billet is discharged and the burr is removed, wherein the cutting point number N of the flame cutting gun is determined according to the slab width after rough rolling and the cutting interval, N = slab width / cutting interval, wherein N is an integer; S4, hot rolling: the cut square billet is rolled on a high-speed wire rod production line, and is concentrated into a heating furnace, heated to 1180-1220℃, and then discharged from the furnace, and is rolled into a diameter φ6.5-φ8mm hot rolled round disc strip drawing material after passing through a non-punching type unit, a punching type unit, a pre-precision rolling unit, a precision rolling unit and a reducing and sizing unit; S5, drawing: the diameter φ6.5-φ8mm hot rolled round disc strip drawing material is treated by skin film and dried on a drawing machine for single or multi-pass drawing, and after annealing, polishing, polishing and galvanizing, a diameter φ3-φ6mm AM05 non-magnetic round steel is finally obtained, the composition of the AM05 non-magnetic round steel is as follows: C: 0.05-0.20%, Si: 0.15-0.30%, Mn: 18-25%, Al: 1.0-2.0%, Nb+V+Ti: 0.04-0.08%, B+Zn: 0.0020-0.0050%, P≤0.045%, S≤0.03%, the rest is Fe and unavoidable impurities.

2. A method of producing high-strength non-magnetic round steel for large submarine cable armorings according to claim 1, characterized in that, In step S4, when rolling on a high-speed wire rod production line, the wire feeding temperature is 850℃, and the air cooling section adopts front and middle section fast cooling + rear section air cooling control mode.

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