A method for producing steel for ultra-thin low-carbon flux-cored welding wire by pickling and cold rolling

Abstract

The present invention discloses a pickling and cold-rolling production method for steel for ultra-thin low-carbon flux-cored welding wire. By standardizing the quality of hot-rolled raw materials and controlling the process parameters of welding, straightening machines, straightening machines, loopers, pickling, and rolling mills, the rolling process of the steel for ultra-thin low-carbon flux-cored welding wire with a thickness of 0.3 to 0.35 mm is stabilized and smooth, thereby avoiding production accidents.

Description

Technical Field

[0001] The invention relates to the technical field of material forming, in particular to a method for producing steel for pickling and cold rolling of ultra-thin low-carbon flux-cored welding wire. Background Art

[0002] The smaller the diameter of a flux-cored welding wire, the better its penetration, which helps control welding depth. Smaller diameter flux-cored wire is primarily used for welding thin plates and is widely used. To meet this demand, steel mills need to develop thinner, specialized steel strips for welding wire. Thicknesses of 0.35mm are a challenge for pickling and cold-rolling production lines, as this is a critical specification and is prone to cracking and even strip breakage. This invention provides a method for pickling and cold-rolling ultra-thin, low-carbon, flux-cored wire steel to ensure stable and smooth production lines and avoid production accidents. Summary of the Invention

[0003] The 0.35mm gauge presents a significant challenge to pickling and cold-rolling production lines, being a critical gauge and prone to the risk of cracking and even breakage. The present invention aims to provide a method for pickling and cold-rolling steel for ultra-thin, low-carbon, flux-cored welding wire. This method ensures stable and smooth production line operation, avoids production accidents, and ensures that the product surface quality meets the requirements for welding wire processing, providing qualified raw materials for subsequent heat treatment.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a method for producing steel for ultra-thin low-carbon flux-cored welding wire by pickling and cold rolling, comprising:

[0006] Check the appearance quality of the raw steel coils: pyramid shape, loose coils, and edge deformation. The pyramid shape and overflow edge should be ≤50mm on each side, and the straightness should be ≤150I. Ensure that the steel coils on the line meet the raw material feeding standards.

[0007] During the uncoiling process, the pinch rollers and the straightening machine pull the strip head and send the strip from the uncoiling machine to the inlet shear, where a section is cut off as the welding position.

[0008] The tail of the previous steel coil and the head of the next steel coil are welded by a welding machine at a welding speed of 7-14m / min;

[0009] The entrance looping volume is maintained at 70%-90%, and the filling speed is ≤600m / min;

[0010] The elongation of the tension leveler is controlled at 1.2%-1.8%, the pickling temperature is 80±5℃, the free acid concentration of the 1# acid tank is 40-100g / l, the free acid concentration of the 2# acid tank is 80-140g / l, the free acid concentration of the 3# acid tank is 110-180g / l, and the pickling speed is 100±30m / min;

[0011] The pH value of the final rinse water should not be lower than 4.5, and the conductivity of the final rinse water should be less than 25μs / cm;

[0012] The rolling process is carried out using a five-stand UCM six-high rolling mill, with a first-pass reduction ratio of 32%-34%, a rolling force of 760-850 kN, and a rolling speed of 50-180 m / min.

[0013] The rolling process is carried out using a five-stand UCM six-high rolling mill, with the second pass reduction ratio being 42%-44%, a rolling force of 810-930 kN, and a rolling speed of 90-320 m / min.

[0014] The steel is rolled using a five-stand UCM six-high mill, with a third-pass reduction ratio of 36%-39%, a rolling force of 700-780 kN, and a rolling speed of 300-500 m / min.

[0015] The rolling process is carried out using a five-stand UCM six-high rolling mill, with the fourth pass reduction ratio ranging from 29% to 33%, a rolling force of 660-740 kN, and a rolling speed of 450-740 m / min.

[0016] The rolling process is carried out using a five-stand UCM six-high rolling mill, with the fifth pass reduction ratio being 0.5%-1.2%, the rolling force being 380-450KN, and the rolling speed being 550-750m / min.

[0017] Furthermore, a steel sleeve with a diameter of 610 mm and a wall thickness of 10 mm, the same width as the steel strip, is placed on the winding core shaft. After the steel coil is wound and slit, a paper sleeve is placed again for winding.

[0018] Furthermore, the finished steel specification for flux-cored welding wire is 0.35×1250mm, the raw material thickness is 2.3×1250mm, the raw steel coil is 20mm in tower shape, the straightness is 40I, and there is no edge cracking; it is welded with SPCC of the same specification at a welding speed of 9mm / min; the entry looper sleeve volume is maintained at 80%-90%, and the sleeve filling speed is 400m / min; the elongation of the straightening machine is controlled at 1.5%, the pickling temperature is 80℃, the free acid concentration of the 1# acid tank is 50g / l, the free acid concentration of the 2# acid tank is 90g / l, the free acid concentration of the 3# acid tank is 120g / l, and the pickling speed is 80m / min; the pH value of the final rinse water is 5.5, and the conductivity of the final rinse water is 18μs / cm; a five-stand UCM six-high rolling mill is used for rolling, with a first-pass reduction rate of 33.45%, a rolling force of 780-807KN, and a rolling speed of 100m / min. The rolling speed is 50-175m / min; the second pass reduction rate is 42.53%, the rolling force is 816-839KN, and the rolling speed is 95-295m / min; the third pass reduction rate is 37.23%, the rolling force is 706-735KN, and the rolling speed is 313-493m / min; the fourth pass reduction rate is 32.39%, the rolling force is 678-734KN, and the rolling speed is 461-725m / min; the fifth pass reduction rate is 1.0%, the rolling force is 399-401KN, and the rolling speed is 570-713m / min; the coiling mandrel is placed with a steel sleeve with a diameter of 610mm, a wall thickness of 10mm, and a width of 1250mm; the steel for 0.35×1250mm flux-cored welding wire is rolled stably without any cracking or even breakage, and the surface quality is qualified, meeting the relevant delivery conditions.

[0019] Furthermore, the finished steel specification for flux-cored welding wire is 0.35×1160mm, the raw material thickness is 2.3×1160mm, the raw steel coil is 22mm in tower shape, the straightness is 42I, and there is no edge cracking; it is welded with SPCC of the same specification at a welding speed of 9mm / min; the entry looper sleeve volume is maintained at 80%-90%, and the sleeve filling speed is 580m / min; the elongation of the straightening machine is controlled at 1.5%, the pickling temperature is 80℃, the free acid concentration of the 1# acid tank is 45g / l, the free acid concentration of the 2# acid tank is 97g / l, the free acid concentration of the 3# acid tank is 125g / l, and the pickling speed is 100m / min; the pH value of the final rinse water is 5.7, and the conductivity of the final rinse water is 19μs / cm; a five-stand UCM six-high rolling mill is used for rolling, with a first-pass reduction rate of 33.27%, a rolling force of 760-793KN, and a rolling speed of 100m / min. The rolling speed is 60-175m / min; the second pass reduction rate is 42.82%, the rolling force is 810-823KN, and the rolling speed is 135-295m / min; the third pass reduction rate is 38.76%, the rolling force is 700-717KN, and the rolling speed is 327-497m / min; the fourth pass reduction rate is 29.4%, the rolling force is 662-713KN, and the rolling speed is 481-739m / min; the fifth pass reduction rate is 1.11%, the rolling force is 382-397KN, and the rolling speed is 589-735m / min; the coiling mandrel is placed with a steel sleeve with a diameter of 610mm, a wall thickness of 10mm, and a width of 1160mm; the steel for 0.35×1160mm flux-cored welding wire is rolled stably without any cracking or even breakage, and the surface quality is qualified, meeting the relevant delivery conditions.

[0020] Furthermore, the finished steel specification for flux-cored welding wire is 0.35×1160mm, the raw material thickness is 2.3×1160mm, the raw steel coil is 45mm in tower shape, the straightness is 45I, and there is no edge cracking; when welding with SPCC of the same specification, the welding speed is 13mm / min; the entry loop sleeve amount is maintained at 80%-90%, and the sleeve filling speed is 390m / min; the elongation of the straightening machine is controlled at 1.7%, the pickling temperature is 75℃, the free acid concentration of the 1# acid tank is 76g / l, the free acid concentration of the 2# acid tank is 115g / l, the free acid concentration of the 3# acid tank is 157g / l, and the pickling speed is 100m / min; the pH value of the final rinse water is 6.1, and the conductivity of the final rinse water is 13μs / cm; a five-stand UCM six-high rolling mill is used for rolling, the first pass reduction rate is 33.59%, the rolling force is 791-802KN, and the rolling speed is 100m / min. The rolling speed is 110-175m / min; the second pass reduction rate is 43.44%, the rolling force is 839-908KN, and the rolling speed is 181-309m / min; the third pass reduction rate is 37.98%, the rolling force is 707-771KN, and the rolling speed is 389-500m / min; the fourth pass reduction rate is 30.04%, the rolling force is 700-740KN, and the rolling speed is 572-736m / min; the fifth pass reduction rate is 0.55%, the rolling force is 395-405KN, and the rolling speed is 577-742m / min; the coiling mandrel is placed with a steel sleeve with a diameter of 610mm, a wall thickness of 10mm, and a width of 1160mm; the steel for 0.35×1160mm flux-cored welding wire is rolled stably without any cracking or even breakage, and the surface quality is qualified, meeting the relevant delivery conditions.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects:

[0022] The present invention standardizes the quality of hot-rolled raw materials and controls the process parameters of welding, straightening machines, straightening machines, loopers, pickling and rolling mills, thereby achieving a stable and smooth rolling process for thin-gauge 0.3-0.35mm low-carbon flux-cored welding wire steel and avoiding production accidents. The invention provides a pickling and cold rolling method for ultra-thin-gauge flux-cored welding wire steel products. DETAILED DESCRIPTION

[0023] In order to prevent the risk of roller damage or strip breakage during cold rolling, the appearance quality of the raw steel coil for flux-cored welding wire must be inspected. The steel strip is not allowed to have edge cracks, and the tower shape and overflow edge must be ≤50mm on each side. The straightness of the raw steel strip must be ≤150I. If it does not meet the inspection requirements, the raw material must be replaced.

[0024] The uncoiler peels the coil's head from the coil, which is then gripped by the uncoiler's pinch rollers and fed into the straightening machine's pinch rollers. The straightening machine's performance is monitored and its engagement adjusted as necessary. During the uncoiling process, the pinch rollers and straightening machine pull the strip's head from the uncoiler into the inlet shear, where a section is cut off to create a welding position.

[0025] The tail of the previous coil is welded to the head of the next coil using a welder, enabling continuous production in the pickling line. Welding speeds range from 7 to 14 m / min. A crescent shear is used to trim the raised corners of the strip to prevent breakage at the weld point. After the crescent shears have trimmed the strip, the strip is accelerated.

[0026] The entrance looper plays the role of storing steel strips and can coordinate the continuous production between pickling and welding. If a welding failure occurs, it can still ensure the normal operation of the strip in pickling in a short time. Therefore, the looper should be kept in a full state at all times, and the loop volume should be maintained at 70% to 90%. The filling speed should be moderate to achieve the purpose of stable operation of the strip. The filling speed is ≤600m / min.

[0027] The tension leveler and scale breaker is located before the pickling tank. Through the combined action of stretching and bending, the strip undergoes elastic-plastic deformation, which not only removes surface oxide scale but also facilitates the subsequent chemical descaling of loosened iron oxide still attached to the strip, thereby increasing the pickling speed. The stretching and bending also effectively improve the strip shape, making it straight and reducing subsequent strip deviation in the line. The elongation of the tension leveler is 1.2% to 1.8%. During the pickling process, the concentration and temperature of each acid tank directly affect the quality of the cold-rolled coil pickling. Over-pickling, under-pickling, and pickling stop spots must be avoided during the pickling process. The pickling temperature for ultra-thin, low-carbon flux-cored welding wire steel is 80±5°C, the free acid concentration in the first acid tank is 40-100 g / l, the free acid concentration in the second acid tank is 80-140 g / l, and the free acid concentration in the third acid tank is 110-180 g / l. The pickling speed is 100±30 m / min.

[0028] The rinsing tank is used to clean the residual acid on the surface of the strip. The pH value of the final rinsing water should not be lower than 4.5, and the conductivity of the final rinsing water should be less than 25μs / cm.

[0029] The five-stand UCM six-high rolling mill is used for rolling. The first three passes should use a larger reduction. The reduction of the first pass is smaller than that of the second and third passes. The reduction rate of the first pass is 32% to 34%, and the rolling force is 760 to 850 kN. In order to prevent the sudden change of thickness entering the rolling mill and causing rolling instability, a slower rolling speed should be adopted, with a rolling speed of 50 to 180 m / min.

[0030] The five-stand UCM six-high rolling mill is used for rolling. The first three passes should use a larger reduction, and the second pass has the largest reduction to fully utilize the plasticity of the material and improve the thinning rate of the finished product. The second pass reduction rate is distributed between 42% and 44%, the rolling force is 810 to 930 kN, and the rolling speed is 90 to 320 m / min.

[0031] The five-stand UCM six-high rolling mill is used for rolling. The first three passes should use a larger reduction, and the reduction of the third pass is slightly smaller than the second pass to improve the stability of the rolling process. The reduction rate of the third pass is 36% to 39%, the rolling force is 700 to 780 kN, and the rolling speed is 300 to 500 m / min.

[0032] The steel is rolled using a five-stand UCM six-high mill. The fourth pass is mainly used to control the plate shape, with a reduction rate of 29% to 33%, a rolling force of 660 to 740 kN, and a rolling speed of 450 to 740 m / min.

[0033] The five-stand UCM six-high rolling mill is used for rolling. The fifth pass has the lowest reduction, which mainly plays the role of replicating the surface roughness and further fine control of the plate shape. The fifth pass reduction rate is distributed between 0.5% and 1.2%, the rolling force is 380 to 450 kN, and the rolling speed is 550 to 750 m / min.

[0034] To prevent thin-gauge strip steel from collapsing, a sleeve is required on the inner ring of the steel coil. A steel sleeve with a diameter of 610mm, a wall thickness of 10mm, and the same width as the steel strip is placed on the coiling mandrel. After the steel coil is coiled and slit, a paper sleeve is placed again for coiling.

[0035] Example 1

[0036] The finished steel for flux-cored welding wire has a specification of 0.35 x 1250 mm, a raw material thickness of 2.3 x 1250 mm, a 20 mm conical coil shape, a straightness of 40°, and no edge cracking. The welding speed is 9 mm / min for SPCC welding of the same specification. The entry looper is maintained at 80% to 90%, and the filling speed is 400 m / min. The elongation of the straightening machine is controlled at 1.5%, the pickling temperature is 80°C, the free acid concentration in the first acid tank is 50 g / l, the free acid concentration in the second acid tank is 90 g / l, and the free acid concentration in the third acid tank is 120 g / l, and the pickling speed is 80 m / min. The pH value of the final rinse water is 5.5, and the conductivity of the final rinse water is 18 μs / cm. Rolling is carried out on a five-stand UCM six-high mill with a first-pass reduction of 33.45%, a rolling force of 780 to 807 kN, and a rolling speed of 50 to 175 m / min. The second pass achieved a reduction of 42.53%, a rolling force of 816-839 kN, and a rolling speed of 95-295 m / min. The third pass achieved a reduction of 37.23%, a rolling force of 706-735 kN, and a rolling speed of 313-493 m / min. The fourth pass achieved a reduction of 32.39%, a rolling force of 678-734 kN, and a rolling speed of 461-725 m / min. The fifth pass achieved a reduction of 1.0%, a rolling force of 399-401 kN, and a rolling speed of 570-713 m / min. The coiling mandrel was placed on a steel sleeve with a diameter of 610 mm, a wall thickness of 10 mm, and a width of 1250 mm. The 0.35×1250 mm flux-cored welding wire steel was rolled stably, without any cracking or breakage, and with satisfactory surface quality, meeting all relevant delivery requirements.

[0037] Example 2

[0038] The finished steel for flux-cored welding wire has a specification of 0.35 x 1160 mm, a raw material thickness of 2.3 x 1160 mm, a 22 mm conical coil shape, a straightness of 42°, and no edge cracking. The welding speed is 9 mm / min for SPCC welding of the same specification. The entry looper is maintained at 80% to 90%, and the filling speed is 580 m / min. The elongation of the straightening machine is controlled at 1.5%, the pickling temperature is 80°C, the free acid concentration in the first acid tank is 45 g / l, the free acid concentration in the second acid tank is 97 g / l, and the free acid concentration in the third acid tank is 125 g / l, and the pickling speed is 100 m / min. The pH value of the final rinse water is 5.7, and the conductivity of the final rinse water is 19 μs / cm. Rolling is carried out on a five-stand UCM six-high mill with a first-pass reduction of 33.27%, a rolling force of 760 to 793 kN, and a rolling speed of 60 to 175 m / min. The second pass achieved a reduction of 42.82%, a rolling force of 810-823 kN, and a rolling speed of 135-295 m / min. The third pass achieved a reduction of 38.76%, a rolling force of 700-717 kN, and a rolling speed of 327-497 m / min. The fourth pass achieved a reduction of 29.4%, a rolling force of 662-713 kN, and a rolling speed of 481-739 m / min. The fifth pass achieved a reduction of 1.11%, a rolling force of 382-397 kN, and a rolling speed of 589-735 m / min. The coiling mandrel was placed on a steel sleeve with a diameter of 610 mm, a wall thickness of 10 mm, and a width of 1160 mm. The 0.35×1160 mm flux-cored welding wire steel was rolled stably, without any cracking or breakage, and with satisfactory surface quality, meeting all relevant delivery requirements.

[0039] Example 3

[0040] The finished steel for flux-cored welding wire has a specification of 0.35 x 1160 mm, a raw material thickness of 2.3 x 1160 mm, a 45 mm coil shape, a straightness of 45°, and no edge cracking. When welding with SPCC wire of the same specification, the welding speed is 13 mm / min. The inlet looper is maintained at 80% to 90% of the looper, and the filling speed is 390 m / min. The elongation of the straightener is controlled at 1.7%, the pickling temperature is 75°C, the free acid concentration in the first acid tank is 76 g / l, the free acid concentration in the second acid tank is 115 g / l, and the free acid concentration in the third acid tank is 157 g / l. The pickling speed is 100 m / min. The pH value of the final rinse water is 6.1, and the conductivity of the final rinse water is 13 μs / cm. Rolling is performed on a five-stand UCM six-high mill. The first pass achieves a 33.59% reduction, a rolling force of 791-802 kN, and a rolling speed of 110-175 m / min. The second pass achieves a 43.44% reduction, a rolling force of 839-908 kN, and a rolling speed of 181-309 m / min. The third pass achieves a 37.98% reduction, a rolling force of 707-771 kN, and a rolling speed of 389-500 m / min. The fourth pass achieves a 30.04% reduction, a rolling force of 700-740 kN, and a rolling speed of 572-736 m / min. The fifth pass achieves a 0.55% reduction, a rolling force of 395-405 kN, and a rolling speed of 577-742 m / min. The coiling mandrel is supported by a steel sleeve with a diameter of 610 mm, a wall thickness of 10 mm, and a width of 1160 mm. The steel used for the 0.35×1160mm flux-cored welding wire is rolled stably without any cracking or even breakage, and the surface quality is qualified, meeting the relevant delivery conditions.

[0041] Comparative Example 1

[0042] The finished steel for flux-cored welding wire has a specification of 0.35 x 1160 mm, a raw material thickness of 2.3 x 1160 mm, a 45 mm coil shape, a straightness of 45°, and no edge cracking. When welding with SPCC wire of the same specification, the welding speed is 13 mm / min. The inlet looper is maintained at 80% to 90% of the looper, and the filling speed is 390 m / min. The elongation of the straightener is controlled at 1.7%, the pickling temperature is 75°C, the free acid concentration in the first acid tank is 76 g / l, the free acid concentration in the second acid tank is 115 g / l, and the free acid concentration in the third acid tank is 157 g / l. The pickling speed is 40 m / min. The pH value of the final rinse water is 5.7, and the conductivity of the final rinse water is 13 μs / cm. Rolling is performed on a five-stand UCM six-high mill. The first pass achieves a 33.57% reduction, a rolling force of 793-801 kN, and a rolling speed of 112-176 m / min. The second pass achieves a 43.32% reduction, a rolling force of 841-902 kN, and a rolling speed of 180-305 m / min. The third pass achieves a 37.97% reduction, a rolling force of 707-771 kN, and a rolling speed of 399-495 m / min. The fourth pass achieves a 30.05% reduction, a rolling force of 710-740 kN, and a rolling speed of 572-736 m / min. The fifth pass achieves a 0.55% reduction, a rolling force of 397-404 kN, and a rolling speed of 576-732 m / min. The coiling mandrel is supported by a steel sleeve with a diameter of 610 mm, a wall thickness of 10 mm, and a width of 1160 mm. Due to the slow pickling speed, the strip stays in the acid tank for too long, causing the surface of the strip to turn yellow. The strip is severely over-pickled and does not meet the pass conditions.

[0043] Comparative Example 2

[0044] The finished steel for flux-cored welding wire has a specification of 0.35 x 1160 mm, a raw material thickness of 2.3 x 1160 mm, a 23 mm conical coil shape, a straightness of 41°, and no edge cracking. The welding speed is 9 mm / min for SPCC welding of the same specification. The entry looper is maintained at 80% to 90%, and the filling speed is 580 m / min. The elongation of the straightening machine is controlled at 1.5%, the pickling temperature is 80°C, the free acid concentration in the first acid tank is 45 g / l, the free acid concentration in the second acid tank is 97 g / l, and the free acid concentration in the third acid tank is 125 g / l, and the pickling speed is 100 m / min. The pH value of the final rinse water is 5.7, and the conductivity of the final rinse water is 19 μs / cm. Rolling is carried out on a five-stand UCM six-high mill with a first-pass reduction of 38%, a rolling force of 800 to 935 kN, and a rolling speed of 100 to 201 m / min. Due to the large reduction rate distribution in the first pass and the fast rolling speed, the rolling process of 0.35×1160mm flux-cored welding wire steel was unstable, the strip was cracked, and the rolling mill had steel piling, which did not meet the relevant delivery conditions.

[0045] Comparative Example 3

[0046] The finished steel for flux-cored welding wire has a specification of 0.35 x 1250 mm, a raw material thickness of 2.3 x 1250 mm, a 17 mm conical coil shape, a straightness of 39°, and no edge cracking. The welding speed is 9 mm / min for SPCC welding of the same specification. The entry looper is maintained at 80% to 89%, and the filling speed is 400 m / min. The elongation of the straightening machine is controlled at 1.5%, the pickling temperature is 80°C, the free acid concentration in the first acid tank is 50 g / l, the free acid concentration in the second acid tank is 90 g / l, and the free acid concentration in the third acid tank is 120 g / l, and the pickling speed is 88 m / min. The pH value of the final rinse water is 5.5, and the conductivity of the final rinse water is 18 μs / cm. Rolling is carried out on a five-stand UCM six-high mill with a first-pass reduction of 33.45%, a rolling force of 780 to 807 kN, and a rolling speed of 50 to 175 m / min. The second pass had a reduction of 48.5%, a rolling force of 875 to 1000 kN, and a rolling speed of 120 to 305 m / min. Due to the excessive reduction in the second pass, the rolling process of the 0.35 x 1160 mm flux-cored welding wire steel was unstable, resulting in strip cracking and steel buildup in the mill, which did not meet the relevant delivery conditions.

[0047] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for producing steel for ultra-thin low-carbon flux-cored welding wire by pickling and cold rolling, characterized in that: include: Check the appearance quality of the raw steel coils: pyramid shape, loose coils, and edge deformation. The pyramid shape and overflow edge should be ≤50mm on each side, and the straightness should be ≤150I. Ensure that the steel coils on the line meet the raw material feeding standards. During the uncoiling process, the pinch rollers and the straightening machine pull the strip head and send the strip from the uncoiling machine to the inlet shear, where a section is cut off as the welding position. The tail of the previous steel coil and the head of the next steel coil are welded by a welding machine at a welding speed of 7-14m / min; The entrance looping volume is maintained at 70%-90%, and the filling speed is ≤600m / min; The elongation of the tension leveler is controlled at 1.2%-1.8%, the pickling temperature is 80±5℃, the free acid concentration of the 1# acid tank is 40-100g / l, the free acid concentration of the 2# acid tank is 80-140g / l, the free acid concentration of the 3# acid tank is 110-180g / l, and the pickling speed is 100±30m / min; The pH value of the final rinse water should not be lower than 4.5, and the conductivity of the final rinse water should be less than 25μs / cm; The rolling process is carried out using a five-stand UCM six-high rolling mill, with a first-pass reduction ratio of 32%-34%, a rolling force of 760-850 kN, and a rolling speed of 50-180 m / min. The rolling process is carried out using a five-stand UCM six-high mill, with the second pass reduction ratio distributed at 42%-44%, a rolling force of 810-930 kN, and a rolling speed of 90-320 m / min. The steel is rolled using a five-stand UCM six-high mill, with the third pass reduction ratio being 36%-39%, a rolling force of 700-780 kN, and a rolling speed of 300-500 m / min. The rolling process is carried out using a five-stand UCM six-high rolling mill, with the fourth pass reduction ratio ranging from 29% to 33%, a rolling force of 660-740 kN, and a rolling speed of 450-740 m / min. The rolling process is carried out using a five-stand UCM six-high rolling mill, with the fifth pass reduction rate ranging from 0.5% to 1.2%, a rolling force of 380-450KN, and a rolling speed of 550-750m / min.

2. The pickling and cold rolling production method for ultra-thin low-carbon flux-cored welding wire steel according to claim 1, characterized in that: A steel sleeve with a diameter of 610mm and a wall thickness of 10mm, the same width as the steel strip, is placed on the winding core shaft. After the steel coil is wound and slit, a paper sleeve is placed again for winding.

3. The pickling and cold rolling production method for ultra-thin low-carbon flux-cored welding wire steel according to claim 1, characterized in that: The finished steel specification for flux-cored welding wire is 0.35×1250mm, the raw material thickness is 2.3×1250mm, the raw steel coil is 20mm in shape, the straightness is 40I, and there is no edge cracking. When welding with SPCC of the same specification, the welding speed is 9mm / min. The inlet looper is kept at 80%-90%, and the filling speed is 400m / min. The elongation of the straightener is controlled at 1.5%, the pickling temperature is 80℃, the free acid concentration in the first acid tank is 50g / l, the free acid concentration in the second acid tank is 90g / l, and the free acid concentration in the third acid tank is 120g / l. The pickling speed is 80m / min. The pH value of the final rinse water is 5.5 , the conductivity of the final rinse water is 18μs / cm; the rolling is carried out using a five-stand UCM six-high rolling mill, with the first pass reduction rate of 33.45%, rolling force of 780-807KN, and rolling speed of 50-175m / min; the second pass reduction rate of 42.53%, rolling force of 816-839KN, and rolling speed of 95-295m / min; the third pass reduction rate of 37.23%, rolling force of 706-735KN, and rolling speed of 313-493m / min; the fourth pass reduction rate of 32.39%, rolling force of 678-734KN, and rolling speed of 461-725m / min; The fifth pass reduction rate is 1.0%, the rolling force is 399-401KN, and the rolling speed is 570-713m / min. The coiling mandrel is placed with a steel sleeve with a diameter of 610mm, a wall thickness of 10mm, and a width of 1250mm. The steel for 0.35×1250mm flux-cored welding wire is rolled stably without any cracking or even breakage, and the surface quality is qualified.

4. The pickling and cold rolling production method for ultra-thin low-carbon flux-cored welding wire steel according to claim 1, characterized in that: The finished steel specification for flux-cored welding wire is 0.35×1160mm, the raw material thickness is 2.3×1160mm, the raw steel coil is 22mm in shape, the straightness is 42I, and there is no edge cracking. When welding with SPCC of the same specification, the welding speed is 9mm / min. The entry looper weight is maintained at 80%-90%, and the filling speed is 580m / min. The elongation of the straightener is controlled at 1.5%, the pickling temperature is 80°C, the free acid concentration in the first acid tank is 45g / l, the free acid concentration in the second acid tank is 97g / l, and the free acid concentration in the third acid tank is 125g / l. The pickling speed is 100m / min. The pH value of the final rinse water is 5.7 The conductivity of the final rinse water is 19μs / cm; the rolling is carried out using a five-stand UCM six-high rolling mill, with a first-pass reduction rate of 33.27%, a rolling force of 760-793KN, and a rolling speed of 60-175m / min; a second-pass reduction rate of 42.82%, a rolling force of 810-823KN, and a rolling speed of 135-295m / min; a third-pass reduction rate of 38.76%, a rolling force of 700-717KN, and a rolling speed of 327-497m / min; a fourth-pass reduction rate of 29.4%, a rolling force of 662-713KN, and a rolling speed of 481-739m / min; The fifth pass reduction rate is 1.11%, the rolling force is 382-397KN, and the rolling speed is 589-735m / min. The coiling mandrel is placed on a steel sleeve with a diameter of 610mm, a wall thickness of 10mm, and a width of 1160mm. The steel for 0.35×1160mm flux-cored welding wire is rolled stably without any cracking or even breakage, and the surface quality is qualified.

5. The pickling and cold rolling production method for ultra-thin low-carbon flux-cored welding wire steel according to claim 1, characterized in that: The finished steel specification for flux-cored welding wire is 0.35×1160mm, the raw material thickness is 2.3×1160mm, the raw steel coil is 45mm in tower shape, the straightness is 45I, and there is no edge cracking; it is welded with SPCC of the same specification at a welding speed of 13mm / min; the entry looper volume is maintained at 80%-90%, and the filling speed is 390m / min; the elongation of the straightening machine is controlled at 1.7%, the pickling temperature is 75℃, the free acid concentration of the 1# acid tank is 76g / l, the free acid concentration of the 2# acid tank is 115g / l, and the free acid concentration of the 3# acid tank is 157g / l, and the pickling speed is 100m / min; the pH value of the final rinse water is 6.1, and the conductivity of the final rinse water is 13μs / cm; it is rolled on a five-stand UCM six-high rolling mill, with a first-pass reduction rate of 33.59%, a rolling force of 791-802KN, and a rolling speed of 100m / min. The speed is 110-175m / min; the second pass reduction rate is 43.44%, the rolling force is 839-908KN, and the rolling speed is 181-309m / min; the third pass reduction rate is 37.98%, the rolling force is 707-771KN, and the rolling speed is 389-500m / min; the fourth pass reduction rate is 30.04%, the rolling force is 700-740KN, and the rolling speed is 572-736m / min; the fifth pass reduction rate is 0.55%, the rolling force is 395-405KN, and the rolling speed is 577-742m / min; the coiling mandrel is placed with a steel sleeve with a diameter of 610mm, a wall thickness of 10mm, and a width of 1160mm; the steel for 0.35×1160mm flux-cored welding wire is rolled stably, without any cracking or even breakage, and the surface quality is qualified.