A core-spun wire outer sheath steel strip and a manufacturing method thereof

Abstract

The application discloses a kind of pure iron core wire outer cladding steel strip and manufacturing method thereof, belong to metallurgical technical field.Its chemical composition and mass percentage are as follows: C≤0.0030%, Mn≤0.030%, S≤0.005%, P≤0.005%, Si≤0.005%, Alt≤0.010%, N≤0.0035%, Ti≤0.0050%, Nb≤0.0050%, Cr≤0.010%, Ni≤0.010%, Cu≤0.010%, Fe≥99.94%, remainder is inevitable impurity element;Its manufacturing method includes smelting, continuous casting, heating, hot rolling, cooling coiling, cover retreats and flattens process.The application uses high-purity industrial pure iron slab as raw material, the obtained steel strip is used as core wire outer cladding, because the content of impurity element is very low, after adding core wire in refining process, it is guaranteed to remove inclusions, and the production requirement of high-purity steel is satisfied.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of metallurgy, and relates to a pure iron cored wire outer cladding steel strip and a manufacturing method thereof. BACKGROUND

[0002] How to obtain high-purity products is a difficulty in the production of steel enterprises at present and is also a development direction of metallurgical technology. The most widely used inclusion treatment technology at present is calcium treatment of aluminum deoxidized steel. By injecting aluminum-calcium or silicon-calcium cored wire into molten steel, Al2O3 inclusions in the steel are converted into low-melting-point calcium-aluminum compounds through calcium treatment, which promotes the floating of the inclusions, reduces the number of oxide inclusions in the steel, improves the cleanliness of the molten steel, improves the casting performance of the molten steel, reduces the problem of nozzle clogging in the tundish, ensures the smooth continuous casting, improves the quality of the steel, improves the alloy yield, and reduces the production cost.

[0003] The cored wire for calcium treatment at present is divided into aluminum-calcium cored wire and silicon-calcium cored wire. The production method is to use aluminum-calcium and silicon-calcium alloys as raw materials, and press them into cored wires with appropriate particle size and particle size according to the composition requirements. Most of them use low-carbon steel cold-rolled steel strips as outer cladding alloy. Although the content of alloying elements in the low-carbon steel cold-rolled steel strip is low, the addition of the cored wire in the refining process still causes fluctuations in the content of some elements, resulting in unstable composition of the molten steel and failing to meet the requirements of high-purity steel. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a pure iron cored wire outer cladding steel strip and a manufacturing method thereof. High-purity industrial pure iron slabs with a content of iron of 99.94% or more are used as raw materials, and cold-rolled steel strips are rolled as outer cladding of the cored wire. Because the content of impurity elements is extremely low, after the cored wire is added in the refining process, the removal of inclusions and the improvement of the purity of the molten steel are ensured, and the composition of the molten steel is more stable, which meets the production requirements of high-purity steel.

[0005] To achieve the above-mentioned application purposes, the technical solutions adopted by the present application are as follows:

[0006] A pure iron cored wire outer cladding steel strip, the chemical composition and mass percentage content of which are as follows: C≤0.0030%, Mn≤0.030%, S≤0.005%, P≤0.005%, Si≤0.005%, Alt≤0.010%, N≤0.0035%, Ti≤0.0050%, Nb≤0.0050%, Cr≤0.010%, Ni≤0.010%, Cu≤0.010%, Fe≥99.94%, and the balance is inevitable impurity elements.

[0007] The thickness of the steel strip is 0.33-0.50 mm, and the width is 35-60 mm.

[0008] The steel belt has tensile strength of 280-340 MPa, yield strength of 160-220 MPa, elongation after breaking of 35-42%, and hardness of 90-105 HV.

[0009] The manufacturing method of the pure iron cored wire outer cladding steel belt comprises smelting, continuous casting, heating, hot rolling, cooling and coiling, cover annealing and flattening processes.

[0010] In the smelting process, an industrial pure iron slab with Fe content of greater than or equal to 99.94% by weight is used as raw material.

[0011] In the heating process, the cast slab stays in the heating furnace for 90-180 minutes, and the temperature of the cast slab out of the heating furnace is 1180-1270 DEG C.

[0012] In the hot rolling process, the cast slab is subjected to five rough rolling passes, the temperature of the five rough rolling passes is 1060-1090 DEG C, the thickness of the rough rolling intermediate slab is 34-40 mm, and after the rough rolling, the cast slab is coiled in a hot coiling box, and after descaling, the cast slab is subjected to hot continuous finishing rolling by a seven-stand lubricated rolling mill, the rough rolling temperature is 1020-1045 DEG C, and the finish rolling temperature is 900-930 DEG C.

[0013] In the cooling and coiling process, a one-stage cooling mode is adopted, and the steel belt is subjected to water cooling laminar cooling at a speed of 50-60 DEG C / s to a coiling temperature of 690-750 DEG C.

[0014] In the cover annealing and flattening process, the annealing temperature of the cover annealing furnace is 600-620 DEG C, and the flattening reduction is 0.5-1.0%.

[0015] The technical scheme of the present application has the following beneficial effects:

[0016] 1. The present application uses an industrial pure iron slab with iron content of greater than or equal to 99.94% by weight as raw material, and rolls the industrial pure iron slab into a cold-rolled steel belt as the outer cladding of the cored wire, so that the content of impurity elements is extremely low, the composition of the molten steel is more stable after the cored wire is added in the refining process, the production requirements of high-quality and high-purity steel are met, and the problem of unstable composition after the cored wire is added in the prior art is solved.

[0017] 2. The pure iron cored wire outer cladding steel belt produced by the present application has tensile strength of 280-340 MPa, yield strength of 160-220 MPa, elongation after breaking of 35-42%, and hardness of 90-105 HV, and has excellent mechanical properties, which meets the use requirements of the outer cladding of the cored wire. DETAILED DESCRIPTION

[0018] The present application will be further described in detail below with reference to the embodiments.

[0019] Embodiment 1

[0020] The thickness of the outer cladding steel strip of the pure iron cored wire produced in the embodiment is 0.33 mm, and the width is 35 mm. The chemical composition and mass percentage are shown in Table 1. The manufacturing method comprises smelting, continuous casting, heating, hot rolling, cooling and coiling, cover annealing and leveling processes. The specific process steps are as follows:

[0021] (1) Smelting and continuous casting process: using industrial pure iron slab with Fe content ≥ 99.94wt% as raw material, the chemical composition of the base plate obtained by smelting and continuous casting and its mass percentage are shown in Table 1;

[0022] (2) Heating process: the holding time of the cast blank in the heating furnace is 160 min, and the cast blank temperature out of the heating furnace is 1250℃;

[0023] (3) Hot rolling process: the 200mm thick slab is roughed by five passes, and the roughing intermediate blank thickness is 37mm. The roughing five-pass temperature is 1060℃. After roughing, it is coiled in a hot coiling box. After descaling, it is hot finished by seven rack lubrication rolling mills. The roughing temperature is 1020℃, and the finish rolling temperature is 900℃;

[0024] (4) Cooling and coiling process: one-stage cooling mode is adopted, and the strip steel is water-cooled laminarly at a speed of 60℃ / s to a coiling temperature of 690℃;

[0025] (5) Cover annealing and leveling process: the cold rolling hard coil enters the cover annealing furnace, the annealing temperature is 600℃, and the leveling reduction is 0.5%.

[0026] The outer cladding steel strip of the pure iron cored wire produced in the embodiment has a tensile strength of 340MPa, a yield strength of 217MPa, an elongation after fracture of 35%, and a hardness of 105HV.

[0027] Example 2

[0028] The thickness of the outer cladding steel strip of the pure iron cored wire produced in the embodiment is 0.34 mm, and the width is 40 mm. The chemical composition and mass percentage are shown in Table 1. The manufacturing method comprises smelting, continuous casting, heating, hot rolling, cooling and coiling, cover annealing and leveling processes. The specific process steps are as follows:

[0029] (1) Smelting and continuous casting process: using industrial pure iron slab with Fe content ≥ 99.94wt% as raw material, the chemical composition of the base plate obtained by smelting and continuous casting and its mass percentage are shown in Table 1;

[0030] (2) Heating process: the holding time of the cast blank in the heating furnace is 165 min, and the cast blank temperature out of the heating furnace is 1255℃;

[0031] (3) Hot rolling process: after five passes of rough rolling, the thickness of the rough rolling intermediate billet is 35 mm, the rough rolling five-pass temperature is 1070°C, and after rough rolling, the hot coil box is coiled, and after descaling, the strip is hot continuous finish-rolled by a seven-stand lubricated rolling mill, the finish-rolling opening rolling temperature is 1030°C, and the finish-rolling temperature is 910°C;

[0032] (4) Cooling and coiling process: one-stage cooling mode is adopted, and the strip is water-cooled laminarly at a speed of 58°C / s to a coiling temperature of 700°C;

[0033] (5) Cover annealing and leveling process: the cold-rolled hard coil enters the cover annealing furnace, the annealing temperature is 600°C, and the leveling reduction is 0.6%.

[0034] The pure iron cored wire outer cladding steel strip produced in this embodiment has a tensile strength of 330 MPa, a yield strength of 220 MPa, an elongation after fracture of 40%, and a hardness of 100 HV.

[0035] Example 3

[0036] The thickness of the pure iron cored wire outer cladding steel strip produced in this embodiment is 0.40 mm, and the width is 45 mm. The chemical composition and mass percentage are shown in Table 1. The manufacturing method includes smelting, continuous casting, heating, hot rolling, cooling and coiling, cover annealing and leveling processes, and the specific process steps are described as follows:

[0037] (1) Smelting and continuous casting process: using industrial pure iron slab with Fe content ≥ 99.94wt% as raw material, the chemical composition of the base plate obtained by smelting and continuous casting and its mass percentage are shown in Table 1;

[0038] (2) Heating process: the holding time of the cast billet in the heating furnace is 140 min, and the cast billet temperature out of the heating furnace is 1180°C;

[0039] (3) Hot rolling process: after five passes of rough rolling, the thickness of the rough rolling intermediate billet is 34 mm, the rough rolling five-pass temperature is 1080°C, and after rough rolling, the hot coil box is coiled, and after descaling, the strip is hot continuous finish-rolled by a seven-stand lubricated rolling mill, the finish-rolling opening rolling temperature is 1040°C, and the finish-rolling temperature is 900°C;

[0040] (4) Cooling and coiling process: one-stage cooling mode is adopted, and the strip is water-cooled laminarly at a speed of 55°C / s to a coiling temperature of 710°C;

[0041] (5) Cover annealing and leveling process: the cold-rolled hard coil enters the cover annealing furnace, the annealing temperature is 610°C, and the leveling reduction is 0.7%.

[0042] The pure iron cored wire outer cladding steel strip produced in this embodiment has a tensile strength of 310 MPa, a yield strength of 190 MPa, an elongation after fracture of 41%, and a hardness of 98 HV.

[0043] Example 4

[0044] The pure iron cored wire outer cladding steel strip produced in this example has a thickness of 0.50 mm and a width of 55 mm, and its chemical composition and mass percentage are shown in Table 1. Its manufacturing method includes smelting, continuous casting, heating, hot rolling, cooling and coiling, cover annealing and leveling processes, and the specific process steps are described as follows:

[0045] (1) Smelting and continuous casting process: using industrial pure iron slab with Fe content ≥ 99.94wt% as raw material, the chemical composition of the base plate obtained by smelting and continuous casting and its mass percentage are shown in Table 1;

[0046] (2) Heating process: the holding time of the cast blank in the heating furnace is 110 min, and the cast blank temperature out of the heating furnace is 1230℃;

[0047] (3) Hot rolling process: the 200mm thick slab is roughed by five passes, and the roughing intermediate blank thickness is 36mm. The roughing five-pass temperature is 1090℃, and after roughing, it is coiled in a hot coiling box. After descaling, it is hot finished by seven rack lubricated rolling mills. The roughing temperature is 1045℃, and the finishing temperature is 930℃;

[0048] (4) Cooling and coiling process: using one-stage cooling mode, the strip is water-cooled laminarly at a speed of 58℃ / s to a coiling temperature of 750℃;

[0049] (5) Cover annealing and leveling process: the cold rolling hard coil enters the cover annealing furnace, the annealing temperature is 620℃, and the leveling reduction is 0.8%.

[0050] The pure iron cored wire outer cladding steel strip produced in this example has a tensile strength of 290MPa, a yield strength of 170MPa, an elongation after fracture of 40%, and a hardness of 93HV.

[0051] Example 5

[0052] The pure iron cored wire outer cladding steel strip produced in this example has a thickness of 0.35 mm and a width of 50 mm, and its chemical composition and mass percentage are shown in Table 1. Its manufacturing method includes smelting, continuous casting, heating, hot rolling, cooling and coiling, cover annealing and leveling processes, and the specific process steps are described as follows:

[0053] (1) Smelting and continuous casting process: using industrial pure iron slab with Fe content ≥ 99.94wt% as raw material, the chemical composition of the base plate obtained by smelting and continuous casting and its mass percentage are shown in Table 1;

[0054] (2) Heating process: the holding time of the cast blank in the heating furnace is 90 min, and the cast blank temperature out of the heating furnace is 1206℃;

[0055] (3) Hot rolling process: after five passes of rough rolling, the thickness of the rough rolling intermediate billet is 38 mm, the rough rolling five-pass temperature is 1080°C, and after rough rolling, the hot coiler is coiled, and after descaling, the hot continuous finishing rolling is carried out by seven lubricated rolling mills, the rough rolling temperature is 1040°C, and the finish rolling temperature is 920°C;

[0056] (4) Cooling and coiling process: one-stage cooling mode is adopted, and the strip is water-cooled laminarly at a speed of 56°C / s to a coiling temperature of 730°C;

[0057] (5) Cover annealing and leveling process: the cold-rolled hard coil enters the cover annealing furnace, the annealing temperature is 620°C, and the leveling reduction rate is 1.0%.

[0058] The pure iron cored wire outer cladding steel strip produced in this embodiment has a tensile strength of 280 MPa, a yield strength of 160 MPa, an elongation after fracture of 42%, and a hardness of 95HV.

[0059] Example 6

[0060] The thickness of the pure iron cored wire outer cladding steel strip produced in this embodiment is 0.33 mm, and the width is 40 mm. The chemical composition and mass percentage are shown in Table 1. The manufacturing method includes smelting, continuous casting, heating, hot rolling, cooling and coiling, cover annealing and leveling processes, and the specific process steps are as follows:

[0061] (1) Smelting and continuous casting process: using industrial pure iron slab with Fe content ≥ 99.94wt% as raw material, the chemical composition of the base plate obtained by smelting and continuous casting and its mass percentage are shown in Table 1;

[0062] (2) Heating process: the holding time of the cast billet in the heating furnace is 170 min, and the cast billet temperature out of the heating furnace is 1260°C;

[0063] (3) Hot rolling process: after five passes of rough rolling, the thickness of the rough rolling intermediate billet is 40 mm, the rough rolling five-pass temperature is 1085°C, and after rough rolling, the hot coiler is coiled, and after descaling, the hot continuous finishing rolling is carried out by seven lubricated rolling mills, the rough rolling temperature is 1035°C, and the finish rolling temperature is 910°C;

[0064] (4) Cooling and coiling process: one-stage cooling mode is adopted, and the strip is water-cooled laminarly at a speed of 59°C / s to a coiling temperature of 710°C;

[0065] (5) Cover annealing and leveling process: the cold-rolled hard coil enters the cover annealing furnace, the annealing temperature is 615°C, and the leveling reduction rate is 0.8%.

[0066] The pure iron cored wire outer cladding steel strip produced in this embodiment has a tensile strength of 310 MPa, a yield strength of 200 MPa, an elongation after fracture of 36%, and a hardness of 94HV.

[0067] Example 7

[0068] The pure iron cored wire produced in this embodiment has an outer steel strip thickness of 0.40 mm and a width of 40 mm. Its chemical composition and mass percentage are shown in Table 1. The manufacturing method includes smelting, continuous casting, heating, hot rolling, cooling and coiling, and shearing and leveling processes. The specific process steps are as follows:

[0069] (1) Smelting and continuous casting process: Using industrial pure iron slabs with Fe content ≥99.94wt% as raw materials, the chemical composition and mass percentage of the substrate obtained by smelting and continuous casting are shown in Table 1;

[0070] (2) Heating process: The billet stays in the heating furnace for 180 minutes and the billet temperature when it exits the heating furnace is 1270℃;

[0071] (3) Hot rolling process: After five passes of rough rolling, the thickness of the intermediate slab of the 200mm thick slab is 35mm. The temperature of the five passes of rough rolling is 1060℃. After rough rolling, it enters the hot coil box for coiling. After descaling, it is hot continuous finishing rolled by a seven-stand lubricated rolling mill. The starting rolling temperature of finishing rolling is 1035℃ and the finishing rolling temperature is 925℃.

[0072] (4) Cooling and coiling process: a single-stage cooling mode is adopted, and the strip is water-cooled at a rate of 53℃ / s to the coiling temperature of 735℃;

[0073] (5) Annealing and leveling process: The cold-rolled hard coil enters the bell-type annealing furnace, the annealing temperature is 605℃, and the leveling reduction rate is 0.6%.

[0074] The pure iron cored wire produced in this embodiment has the following outer steel strip: tensile strength 300MPa, yield strength 190MPa, elongation after fracture 37%, and hardness 90HV.

[0075] Example 8

[0076] The pure iron cored wire produced in this embodiment has an outer steel strip thickness of 0.45 mm and a width of 60 mm. Its chemical composition and mass percentage are shown in Table 1. The manufacturing method includes smelting, continuous casting, heating, hot rolling, cooling and coiling, and shearing and leveling processes. The specific process steps are as follows:

[0077] (1) Smelting and continuous casting process: Using industrial pure iron slabs with Fe content ≥99.94wt% as raw materials, the chemical composition and mass percentage of the substrate obtained by smelting and continuous casting are shown in Table 1;

[0078] (2) Heating process: The billet stays in the heating furnace for 150 minutes and the billet temperature when it exits the heating furnace is 1245℃;

[0079] (3) Hot rolling process: the 200mm-thick slab is rolled by five rough rolling passes, and the rough rolling intermediate billet thickness is 36mm, the rough rolling five-pass temperature is 1065°C, and after rough rolling, the rough rolling intermediate billet is wound in a hot coiler, and after descaling, the rough rolling intermediate billet is hot continuous finish-rolled by seven lubricated rolling mills, the finish-rolling opening rolling temperature is 1040°C, and the finish-rolling final rolling temperature is 915°C;

[0080] (4) Cooling and coiling process: a one-stage cooling mode is adopted, and the strip steel is water-cooled laminarly at a speed of 50°C / s to a coiling temperature of 740°C;

[0081] (5) Batch annealing and skin-passing process: the cold-rolled hard coil is put into a batch annealing furnace, the annealing temperature is 615°C, and the skin-passing reduction is 0.7%.

[0082] The outer cladding steel strip of the pure iron cored wire produced in the embodiment has a tensile strength of 320MPa, a yield strength of 180MPa, and an elongation after fracture of 38%, and a hardness of 96HV.

[0083] Table 1 Chemical composition and mass content (%) of the outer cladding steel strip of the pure iron cored wire in each embodiment

[0084]

Claims

1. A core-spun wire outer sheath steel strip of pure iron characterized in that, The chemical composition and mass percentage content are: C≤0.0015%, Mn≤0.013%, S≤0.005%, P≤0.005%, Si≤0.005%, Alt≤0.004%, N≤0.0035%, Ti≤0.0050%, Nb≤0.0050%, Cr≤0.007%, Ni≤0.004%, Cu≤0.005%, Fe≥99.94%, and the rest is inevitable impurity elements; The steel strip has tensile strength of 280-340 MPa, yield strength of 160-220 MPa, elongation after fracture of 35-42%, and hardness of 90-105 HV. The manufacturing method of the steel strip comprises smelting, continuous casting, heating, hot rolling, cooling and coiling, cover annealing and skin pass rolling processes. In the smelting process, the industrial pure iron slab with Fe content of ≥99.94wt% is used as raw material. In the hot rolling process, after five-pass rough rolling, the rough rolling five-pass temperature is 1060-1090℃, and after rough rolling, the rough rolled piece is coiled in a hot coiling box, and after descaling, the piece is subjected to finish rolling, the finish rolling opening rolling temperature is 1020-1045℃, and the finish rolling temperature is 900-930℃; the rough rolling intermediate piece thickness is 34-40mm, and after descaling, the piece is subjected to hot continuous finish rolling by seven lubricated rolling mills. In the cooling and coiling process, one-stage cooling mode is adopted, and the steel strip is subjected to water cooling laminar cooling at a speed of 50-60℃ / s to a coiling temperature of 690-750℃. In the cover annealing and skin pass rolling process, the annealing temperature of the cover annealing furnace is 605-620℃, and the skin pass rolling reduction is 0.5-1.0%.

2. The pure iron cored wire overcoated steel strip according to claim 1, characterized in that, The steel strip has a thickness of 0.33-0.50mm and a width of 35-60mm.

3. The method of manufacturing a coreless wire outer clad steel strip of pure iron according to claim 1 or 2, characterized in that, The manufacturing method comprises smelting, continuous casting, heating, hot rolling, cooling and coiling, cover annealing and skin pass rolling processes. In the smelting process, the industrial pure iron slab with Fe content of ≥99.94wt% is used as raw material. In the hot rolling process, after five-pass rough rolling, the rough rolling five-pass temperature is 1060-1090℃, and after rough rolling, the rough rolled piece is coiled in a hot coiling box, and after descaling, the piece is subjected to finish rolling, the finish rolling opening rolling temperature is 1020-1045℃, and the finish rolling temperature is 900-930℃; the rough rolling intermediate piece thickness is 34-40mm, and after descaling, the piece is subjected to hot continuous finish rolling by seven lubricated rolling mills. In the cooling and coiling process, one-stage cooling mode is adopted, and the steel strip is subjected to water cooling laminar cooling at a speed of 50-60℃ / s to a coiling temperature of 690-750℃. In the cover annealing and skin pass rolling process, the annealing temperature of the cover annealing furnace is 605-620℃, and the skin pass rolling reduction is 0.5-1.0%.

4. The method of manufacturing a coreless wire outer clad steel strip of pure iron according to claim 3, characterized in that, In the heating process, the cast blank stays in the heating furnace for 90-180min, and the cast blank temperature out of the heating furnace is 1180-1270℃.

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