CN110760859A - Continuous production method for 400 series stainless steel hot rolled steel strip by fluorine-free acid pickling and special surfactant - Google Patents
Continuous production method for 400 series stainless steel hot rolled steel strip by fluorine-free acid pickling and special surfactant Download PDFInfo
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- CN110760859A CN110760859A CN201911026356.1A CN201911026356A CN110760859A CN 110760859 A CN110760859 A CN 110760859A CN 201911026356 A CN201911026356 A CN 201911026356A CN 110760859 A CN110760859 A CN 110760859A
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
- C23G1/08—Iron or steel
- C23G1/081—Iron or steel solutions containing H2SO4
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G3/00—Apparatus for cleaning or pickling metallic material
- C23G3/02—Apparatus for cleaning or pickling metallic material for cleaning wires, strips, filaments continuously
- C23G3/027—Associated apparatus, e.g. for pretreating or after-treating
Abstract
The invention discloses a continuous production method of a 400 series stainless steel hot rolled steel strip by fluoride-free acid cleaning and a special surfactant, which is characterized in that: the method comprises the following steps: uncoiling; scale breaking; shot blasting; acid washing with sulfuric acid: pickling the steel strip in a sulfuric acid pickling tank, and adding a surfactant into a sulfuric acid solution; the concentration of the surfactant is 10-50 g/l, and the concentration of the sulfuric acid is 150-280 g/l; the composition of the surfactant is as follows: 10-15% of carboxymethyl cellulose, 3-5% of biochemical fulvic acid, 20-40% of 2-aminoethanol, 5-10% of 8-hydroxyquinoline-5-sulfonic acid and 42-50% of water; brushing and washing; nitric acid passivation: passivating the steel strip in a nitric acid passivation tank, wherein the concentration of nitric acid is 100-180 g/l; finally, cleaning and drying; and (4) coiling. The invention adopts the method of combining sulfuric acid + surfactant pickling and nitric acid passivation for production, avoids using hydrofluoric acid, reduces the pickling cost and improves the pickling efficiency.
Description
Technical Field
The invention relates to an improvement of a pickling method for a 400-series stainless steel hot-rolled steel strip, belongs to the technical field of production of stainless steel hot-rolled steel strips, and particularly relates to a continuous production method for the 400-series stainless steel hot-rolled steel strip by fluoride-free pickling and a special surfactant.
Background
The 400 series stainless steel is nickel-free stainless steel, and has a high scale thickness because the oxidation resistance is lower than that of the common 200 series stainless steel, 300 series stainless steel and duplex stainless steel, and the scale structure and components are complicated because the 400 series stainless steel contains one or more of alloy elements such as silicon, titanium, molybdenum, aluminum, copper and the like. There are three common ways of removing scale from steel strip: the method has the advantages that firstly, the physical method is adopted, oxide skin on the surface of the steel strip is clearly removed through sand blasting, and the problems that equipment investment is large, the working environment is severe, dust and noise pollution are serious, and large-scale production of products such as the steel strip and a wire rod is difficult to realize exist; secondly, a chemical method, namely high-temperature molten salt alkaline leaching or acid pickling by sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid and other solutions, has the problems of severe working environment and serious environmental pollution; thirdly, a physical and chemical method, namely, phosphorus breaking and shot blasting mechanical phosphorus removal are carried out in the early stage, and the remaining oxide skin is removed and surface passivation is completed in a chemical pickling mode, which is also the most common oxide skin removal method for 400 series stainless steel, but the method generally needs mixed acid pickling, hydrofluoric acid is one of the main acid solutions in the mixed acid pickling, and the problems are that: (1) hydrofluoric acid is expensive and the production cost is high; (2) the hydrofluoric acid solution has great harm to human bodies, and serious safety accidents can be caused by carelessness; (3) fluorine-containing wastewater and acid mist have serious environmental pollution, and fluorine ions are difficult to remove after entering water sources and soil, so that the environmental hazard is large.
Through search, the Chinese patent 'a 400 series stainless steel annealing wire catalytic pickling solution and pickling method' filed by the university of Anhui industry at 2015.12.25, the patent publication number is CN105543865A, which discloses: the method comprises the steps of injecting 10-18% of prepared concentrated sulfuric acid containing 98%, 2.0-4.0% of sodium fluoride, 3.0-5.0% of potassium persulfate, 1.0-1.5% of EDTA (ethylene diamine tetraacetic acid), 0.1-0.3% of urotropine, 0.3-0.5% of sodium chloride, 0.05-0.1% of sodium dodecyl sulfate and the balance of water into a pickling tank, and directly soaking the stainless steel annealing wire into pickling solution for pickling, wherein the method is efficient and economical, but only suitable for wire production and cannot be applied to production of stainless steel plates and strips. The Chinese patent application 'a ferritic stainless steel cold-rolled strip steel pickling method' filed by Shanxi Tai steel stainless Steel gmbh at 2018.06.01, the publication number of which is CN108396366A, discloses: the method sequentially comprises the following steps: the method can only be applied to pickling of cold-rolled steel strips, and hydrofluoric acid must be used in the production process. Chinese patent application "a stainless steel surface treating agent and its preparation method and application method" filed by Chengyi science and technology Limited in high Ming district of Fushan City at 2016.11.30, its publication number is CN106521525A, which discloses: the stainless steel surface treating agent adopts nitric acid, hydrofluoric acid and triethylene glycol as acidic substances in a strong acid component, adopts urotropine, coconut diethanol amine fatty acid, triethanolamine oleate soap, fatty acid methyl acetate ethoxylate and alkylphenol polyoxyethylene ether to compound as main surface active components, and adopts sodium chloride, sodium metasilicate and sodium citrate as water-soluble salt components. The method still uses hydrofluoric acid and is difficult to apply to continuous production of steel strip.
The 400 series stainless steel hot rolled steel strip has high surface oxide scale thickness and complex oxide scale structure, and simultaneously, the defect of under-pickling or over-pickling is easy to occur in the pickling process due to poor corrosion resistance. The conventional acid cleaning process generally cannot avoid the use of hydrofluoric acid, the danger of the hydrofluoric acid is high, and the fluorine-containing wastewater is difficult to treat. The production efficiency of part of the fluoride-free pickling process is low, or the fluoride-free pickling process is only suitable for wire rod and wire rod production and is difficult to popularize to the large-scale pickling of the hot rolled steel strip, so that the finding of the efficient fluoride-free pickling method applied to the pickling of the 400-series stainless steel hot rolled steel strip is very important.
Disclosure of Invention
The invention aims to provide a continuous production method for pickling 400 series stainless steel hot rolled steel strips without fluorine acid, which is safe and environment-friendly, reduces pickling cost and improves pickling quality.
In order to achieve the above purposes, the technical scheme adopted by the invention is as follows:
the continuous production method for the fluorine-free acid pickling of the 400-series stainless steel hot rolled steel strip is characterized by comprising the following steps of: it comprises the following steps:
(I) uncoiling: after a 400 series stainless steel hot rolled steel coil is uncoiled by an uncoiler, a strip head and the strip tail of the previous coil are cut and leveled by a double-edge guillotine type shearing machine, and then the welding is carried out by an MIG argon arc welding machine, so that the adjacent coils are connected into a continuous steel strip; in order to ensure the welding quality, the thickness difference of steel coils at two ends of a welding seam is required to be less than 3 mm; the welded steel strip enters a front loop, the length of the front loop is 500 meters, and the steel strip with the length of 500 meters can be stored at most, so that the normal operation of the subsequent processes is ensured in the steel strip welding process;
(II) scale breaking: the front and the back of the scale breaker are respectively provided with a tensioning machine, and under the tension action of the tensioning machines, the steel belt out of the front loop sequentially passes through the tensioning machine at the front side, the scale breaker and the tensioning machine at the back side; the rolling reduction of a bending roller of the scale breaker is less than or equal to 75 mm, and the rolling reduction of a straightening roller is less than or equal to 80 mm; properly adjusting the production tension of the tensioning machine according to the thickness of the steel strip to ensure that the outlet tension of the scale breaker meets the requirement and ensure that the elongation of the steel strip is more than 1.2 percent; the requirements for controlling the outlet tension of the scale breaker are shown in table 1;
table 1:
| thickness of steel strip/mm | 3.0 | 3.5 | 4.0 | 4.5 | 5.0 | 5.5 | 6.0 |
| tension/kN | 360 | 360 | 380 | 380 | 400 | 400 | 420 |
(III) shot blasting: the front and the back of the shot blasting machine are respectively provided with a tensioning machine, under the tension action of the tensioning machines, the steel belt sequentially passes through the tensioning machine on the front side, the shot blasting machine and the tensioning machine on the back side, and shot blasting treatment is carried out on the surface of the steel belt through the shot blasting machines; the shot blasting machine adopts a mixed abrasive of steel shots and steel grits, the grain sizes of the steel shots and the steel grits are 0.3-0.5 mm, and the weight ratio of the steel shots to the steel grits is 3: 7; in the production process, the shot blasting machine is provided with two units, namely 16 throwing heads, the rotating speed and the sand discharge amount of the throwing heads are controlled by throwing head current, the throwing head current is controlled according to the thickness of a steel strip, and the requirement of the throwing head current control is shown in table 2;
table 2:
| thickness of steel strip/mm | 3.0 | 3.5 | 4.0 | 4.5 | 5.0 | 5.5 | 6.0 |
| current/A | 95 | 95 | 90 | 90 | 85 | 85 | 80 |
(IV) sulfuric acid pickling: a tensioning machine is arranged on the front side of the sulfuric acid pickling tank, the steel strip is conveyed into the sulfuric acid pickling tank under the tension action of the tensioning machine for sulfuric acid pickling, the length of the sulfuric acid pickling tank is 22m, and a surfactant is added into the sulfuric acid solution for improving the sulfuric acid pickling efficiency; wherein the concentration of the surfactant is 10-50 g/l, the concentration of the sulfuric acid is 150-280 g/l, and the temperature is 60-100 ℃; adjusting the running speed of the steel strip according to the thickness of the steel strip and the concentration of sulfuric acid and surfactant, wherein the range is 15-40 m/min; the surfactant comprises the following components in percentage by weight: carboxymethyl cellulose: 10-15%, biochemical fulvic acid: 3-5%, 2-aminoethanol: 20-40%, 8-hydroxyquinoline-5-sulfonic acid: 5-10%, water: 42-50%; the sulfuric acid is used for removing residual oxide skin through oxidation-reduction reaction, and the surfactant is used for destroying metal bonds between the oxide skin and a matrix and improving the pickling efficiency of the sulfuric acid;
(V) brushing: the steel belt coming out of the sulfuric acid pickling tank enters a brushing tank, the length of the brushing tank is 7m, the medium is industrial soft water, the sulfuric acid solution and the surfactant remaining on the surface of the steel belt are brushed under the action of a brush roller, and after the brushing is finished, water stains on the surface of the steel belt are squeezed by a squeezing roller;
(VI) passivating by nitric acid: the steel strip discharged from the brushing groove enters a nitric acid passivation groove for passivation, the length of the nitric acid passivation groove is 18m, the concentration of nitric acid is 100-180 g/l, and the temperature is 20-50 ℃, so that the steel strip is fully passivated;
(VII) final cleaning and drying: the final cleaning tank is divided into two sections, one section is a final cleaning section, the other section is a drying section, and the rear side of the final cleaning tank is provided with a tensioning machine; the steel belt from the nitric acid passivation tank sequentially passes through a final cleaning section, a drying section and a tensioning machine of the final cleaning tank, the length of the final cleaning section of the final cleaning tank is 10m, the medium is industrial soft water, the residual nitric acid solution on the surface of the steel belt is scrubbed under the action of a brush roll, the residual nitric acid solution on the surface of the steel belt is prevented from causing transitional pickling, water stains on the surface of the steel belt are squeezed by a squeezing roll, and the steel belt passes through the drying section and is dried by hot air through steam, so that the surface of the steel belt is prevented from being polluted in the subsequent operation; the dried steel strip enters a rear loop to wait for curling, and the length of the rear loop is 400 meters;
(eighth), winding: and (4) feeding the steel strip which comes out from the rear loop into a coiling machine for coiling operation, and cutting two ends of a welding line through a slitting shear when the steel strip is coiled to the tail of the strip to obtain a finished product of the 400-series stainless steel pickled steel coil.
The thickness of the 400 series stainless steel hot rolled steel strip is less than or equal to 6.0mm, and the steel types are ferrite stainless steel hot rolled steel strips such as 06Cr13, 10Cr17, 022Cr11Ti and the like, or martensite stainless steel hot rolled steel strips such as 12Cr13, 20Cr13, 30Cr13, 40Cr13 and the like.
A surfactant special for fluorine-free acid cleaning of 400 series stainless steel hot rolled steel strips is characterized in that: the composite material comprises the following components in percentage by weight: carboxymethyl cellulose: 10-15%, biochemical fulvic acid: 3-5%, 2-aminoethanol: 20-40%, 8-hydroxyquinoline-5-sulfonic acid: 5-10%, water: 42-50%.
The invention has the beneficial effects that: the invention adopts a continuous production method of non-fluorine acid pickling by combining sulfuric acid + surfactant acid pickling and nitric acid passivation, avoids using hydrofluoric acid, avoids the environmental and safety problems caused by using hydrofluoric acid, and reduces the acid pickling cost; meanwhile, proper process speed, phosphorus breaking, shot blasting and pickling processes are set according to the thickness of the steel coil, so that the defects of scale residue, over pickling and other pickling defects easily caused by 400 series stainless steel are overcome, and the pickling efficiency is improved.
Detailed Description
The present invention will be described in further detail with reference to specific examples, but the present invention is not limited to these examples.
Example 1:
a fluorine-free acid pickling continuous production method of a hot-rolled 10Cr17 stainless steel strip with the thickness of 3.0mm comprises the following steps:
(I) uncoiling: uncoiling 10Cr17 stainless steel hot rolled steel coils with the thickness of 3.0mm by an uncoiler, shearing the head of the strip and the tail of the previous coil of the strip by a double-edge guillotine type shearing machine to be level, and then welding by an MIG argon arc welding machine to connect adjacent coils of the strip into a continuous steel strip; in order to ensure the welding quality, the thickness difference of steel coils at two ends of a welding seam is required to be less than 3 mm; the welded steel strip enters a front loop, the length of the front loop is 500 meters, and the steel strip with the length of 500 meters can be stored at most, so that the normal operation of the subsequent processes is ensured in the steel strip welding process;
(II) scale breaking: the front and the back of the scale breaker are respectively provided with a tensioning machine, and under the tension action of the tensioning machines, the steel belt out of the front loop sequentially passes through the tensioning machine at the front side, the scale breaker and the tensioning machine at the back side; the rolling reduction of a bending roller of the scale breaker is less than or equal to 75 mm, and the rolling reduction of a straightening roller is less than or equal to 80 mm; properly adjusting the production tension of the tensioning machine according to the thickness of the steel strip to ensure that the outlet tension of the scale breaker meets the requirement and ensure that the elongation of the steel strip is more than 1.2 percent; the outlet tension of the scale breaker is 360 kN;
(III) shot blasting: the front and the back of the shot blasting machine are respectively provided with a tensioning machine, under the tension action of the tensioning machines, the steel belt sequentially passes through the tensioning machine on the front side, the shot blasting machine and the tensioning machine on the back side, and shot blasting treatment is carried out on the surface of the steel belt through the shot blasting machines; the shot blasting machine adopts a mixed abrasive of steel shots and steel grits, the grain sizes of the steel shots and the steel grits are 0.3-0.5 mm, and the weight ratio of the steel shots to the steel grits is 3: 7; in the production process, the shot blasting machine is provided with two units, namely 16 blasting heads, and the blasting head current is 95A;
(IV) sulfuric acid pickling: a tensioning machine is arranged on the front side of the sulfuric acid pickling tank, the steel strip is conveyed into the sulfuric acid pickling tank under the tension action of the tensioning machine for sulfuric acid pickling, the length of the sulfuric acid pickling tank is 22m, and a surfactant is added into the sulfuric acid solution for improving the sulfuric acid pickling efficiency; wherein the concentration of the surfactant is 50g/l, the concentration of the sulfuric acid is 280g/l, the temperature is 60 ℃, and the running speed of the steel belt is 40 m/min; the surfactant comprises the following components in percentage by weight: carboxymethyl cellulose: 10%, biochemical fulvic acid: 3%, 2-aminoethanol: 40%, 8-hydroxyquinoline-5-sulfonic acid: 5%, water: 42%; the sulfuric acid is used for removing residual oxide skin through oxidation-reduction reaction, and the surfactant is used for destroying metal bonds between the oxide skin and a matrix and improving the pickling efficiency of the sulfuric acid;
(V) brushing: the steel belt coming out of the sulfuric acid pickling tank enters a brushing tank, the length of the brushing tank is 7m, the medium is industrial soft water, the sulfuric acid solution and the surfactant remaining on the surface of the steel belt are brushed under the action of a brush roller, and after the brushing is finished, water stains on the surface of the steel belt are squeezed by a squeezing roller;
(VI) passivating by nitric acid: the steel strip discharged from the brushing groove enters a nitric acid passivation groove for passivation, the length of the nitric acid passivation groove is 18m, the concentration of nitric acid is 100g/l, and the temperature is 50 ℃, so that the steel strip is fully passivated;
(VII) final cleaning and drying: the final cleaning tank is divided into two sections, one section is a final cleaning section, the other section is a drying section, and the rear side of the final cleaning tank is provided with a tensioning machine; the steel belt from the nitric acid passivation tank sequentially passes through a final cleaning section, a drying section and a tensioning machine of the final cleaning tank, the length of the final cleaning section of the final cleaning tank is 10m, the medium is industrial soft water, the residual nitric acid solution on the surface of the steel belt is scrubbed under the action of a brush roll, the residual nitric acid solution on the surface of the steel belt is prevented from causing transitional pickling, water stains on the surface of the steel belt are squeezed by a squeezing roll, and the steel belt passes through the drying section and is dried by hot air through steam, so that the surface of the steel belt is prevented from being polluted in the subsequent operation; the dried steel strip enters a rear loop to wait for curling, and the length of the rear loop is 400 meters;
(eighth), winding: and (4) feeding the steel strip which comes out from the rear loop into a coiling machine for coiling operation, and cutting two ends of a welding line through a slitting shear when the steel strip is coiled to the tail of the strip to obtain a finished product of the 400-series stainless steel pickled steel coil.
The pickled steel strip is detected on line before curling, and the apparent quality of the pickled steel strip is qualified by detecting that the surface of the steel strip has no defects of under-pickling, residual iron scale, under-pickling, over-pickling, acid spots and the like.
Example 2:
a fluorine-free acid pickling continuous production method of a 12Cr13 stainless steel hot-rolled steel strip with the thickness of 4.5mm comprises the following steps:
(I) uncoiling: uncoiling a 12Cr13 stainless steel hot-rolled steel coil with the thickness of 4.5mm by an uncoiler, shearing a head of the strip and the tail of the previous coil of the steel coil to be flush by a double-edge guillotine type shearing machine, and then welding by an MIG argon arc welding machine to connect adjacent coils of the steel coil into a continuous steel strip; in order to ensure the welding quality, the thickness difference of steel coils at two ends of a welding seam is required to be less than 3 mm; the welded steel strip enters a front loop, the length of the front loop is 500 meters, and the steel strip with the length of 500 meters can be stored at most, so that the normal operation of the subsequent processes is ensured in the steel strip welding process;
(II) scale breaking: the front and the back of the scale breaker are respectively provided with a tensioning machine, and under the tension action of the tensioning machines, the steel belt out of the front loop sequentially passes through the tensioning machine at the front side, the scale breaker and the tensioning machine at the back side; the rolling reduction of a bending roller of the scale breaker is less than or equal to 75 mm, and the rolling reduction of a straightening roller is less than or equal to 80 mm; properly adjusting the production tension of the tensioning machine according to the thickness of the steel strip to ensure that the outlet tension of the scale breaker meets the requirement and ensure that the elongation of the steel strip is more than 1.2 percent; the outlet tension of the scale breaker is 380 kN;
(III) shot blasting: the front and the back of the shot blasting machine are respectively provided with a tensioning machine, under the tension action of the tensioning machines, the steel belt sequentially passes through the tensioning machine on the front side, the shot blasting machine and the tensioning machine on the back side, and shot blasting treatment is carried out on the surface of the steel belt through the shot blasting machines; the shot blasting machine adopts a mixed abrasive of steel shots and steel grits, the grain sizes of the steel shots and the steel grits are 0.3-0.5 mm, and the weight ratio of the steel shots to the steel grits is 3: 7; in the production process, the shot blasting machine is provided with two units, namely 16 throwing heads, the rotating speed and the sand discharge amount of the throwing heads are controlled by throwing head current, and the throwing head current is 90A;
(IV) sulfuric acid pickling: a tensioning machine is arranged on the front side of the sulfuric acid pickling tank, the steel strip is conveyed into the sulfuric acid pickling tank under the tension action of the tensioning machine for sulfuric acid pickling, the length of the sulfuric acid pickling tank is 22m, and a surfactant is added into the sulfuric acid solution for improving the sulfuric acid pickling efficiency; wherein the concentration of the surfactant is 30g/l, the concentration of the sulfuric acid is 210g/l, the temperature is 80 ℃, and the running speed of the steel belt is 28 m/min; the surfactant comprises the following components in percentage by weight: carboxymethyl cellulose: 13%, biochemical fulvic acid: 4%, 2-aminoethanol: 30%, 8-hydroxyquinoline-5-sulfonic acid: 7%, water: 46 percent; the sulfuric acid is used for removing residual oxide skin through oxidation-reduction reaction, and the surfactant is used for destroying metal bonds between the oxide skin and a matrix and improving the pickling efficiency of the sulfuric acid;
(V) brushing: the steel belt coming out of the sulfuric acid pickling tank enters a brushing tank, the length of the brushing tank is 7m, the medium is industrial soft water, the sulfuric acid solution and the surfactant remaining on the surface of the steel belt are brushed under the action of a brush roller, and after the brushing is finished, water stains on the surface of the steel belt are squeezed by a squeezing roller;
(VI) passivating by nitric acid: the steel strip discharged from the brushing groove enters a nitric acid passivation groove for passivation, the length of the nitric acid passivation groove is 18m, the concentration of nitric acid is 140g/l, and the temperature is 35 ℃, so that the steel strip is fully passivated;
(VII) final cleaning and drying: the final cleaning tank is divided into two sections, one section is a final cleaning section, the other section is a drying section, and the rear side of the final cleaning tank is provided with a tensioning machine; the steel belt from the nitric acid passivation tank sequentially passes through a final cleaning section, a drying section and a tensioning machine of the final cleaning tank, the length of the final cleaning section of the final cleaning tank is 10m, the medium is industrial soft water, the residual nitric acid solution on the surface of the steel belt is scrubbed under the action of a brush roll, the residual nitric acid solution on the surface of the steel belt is prevented from causing transitional pickling, water stains on the surface of the steel belt are squeezed by a squeezing roll, and the steel belt passes through the drying section and is dried by hot air through steam, so that the surface of the steel belt is prevented from being polluted in the subsequent operation; the dried steel strip enters a rear loop to wait for curling, and the length of the rear loop is 400 meters;
(eighth), winding: and (4) feeding the steel strip which comes out from the rear loop into a coiling machine for coiling operation, and cutting two ends of a welding line through a slitting shear when the steel strip is coiled to the tail of the strip to obtain a finished product of the 400-series stainless steel pickled steel coil.
The pickled steel strip is detected on line before curling, and the apparent quality of the pickled steel strip is qualified by detecting that the surface of the steel strip has no defects of under-pickling, residual iron scale, under-pickling, over-pickling, acid spots and the like.
Example 3:
a fluoride-free acid pickling continuous production method of a 06Cr13 stainless steel hot rolled steel strip with the thickness of 6.0mm comprises the following steps:
(I) uncoiling: after a 06Cr13 stainless steel hot rolled steel coil with the thickness of 6.0mm is uncoiled by an uncoiler, a tape head and the tape tail of the previous steel coil are cut and leveled by a double-edge guillotine type shearing machine, and then the welding is carried out by an MIG argon arc welding machine, so that the adjacent steel coils are connected into a continuous steel tape; in order to ensure the welding quality, the thickness difference of steel coils at two ends of a welding seam is required to be less than 3 mm; the welded steel strip enters a front loop, the length of the front loop is 500 meters, and the steel strip with the length of 500 meters can be stored at most, so that the normal operation of the subsequent processes is ensured in the steel strip welding process;
(II) scale breaking: the front and the back of the scale breaker are respectively provided with a tensioning machine, and under the tension action of the tensioning machines, the steel belt out of the front loop sequentially passes through the tensioning machine at the front side, the scale breaker and the tensioning machine at the back side; the rolling reduction of a bending roller of the scale breaker is less than or equal to 75 mm, and the rolling reduction of a straightening roller is less than or equal to 80 mm; properly adjusting the production tension of the tensioning machine according to the thickness of the steel strip to ensure that the outlet tension of the scale breaker meets the requirement and ensure that the elongation of the steel strip is more than 1.2 percent; the outlet tension of the scale breaker is 420 kN;
(III) shot blasting: the front and the back of the shot blasting machine are respectively provided with a tensioning machine, under the tension action of the tensioning machines, the steel belt sequentially passes through the tensioning machine on the front side, the shot blasting machine and the tensioning machine on the back side, and shot blasting treatment is carried out on the surface of the steel belt through the shot blasting machines; the shot blasting machine adopts a mixed abrasive of steel shots and steel grits, the grain sizes of the steel shots and the steel grits are 0.3-0.5 mm, and the weight ratio of the steel shots to the steel grits is 3: 7; in the production process, the shot blasting machine is provided with two units, namely 16 throwing heads, the rotating speed and the sand discharge amount of the throwing heads are controlled by throwing head current, and the throwing head current is 80A;
(IV) sulfuric acid pickling: a tensioning machine is arranged on the front side of the sulfuric acid pickling tank, the steel strip is conveyed into the sulfuric acid pickling tank under the tension action of the tensioning machine for sulfuric acid pickling, the length of the sulfuric acid pickling tank is 22m, and a surfactant is added into the sulfuric acid solution for improving the sulfuric acid pickling efficiency; wherein the concentration of the surfactant is 10g/l, the concentration of the sulfuric acid is 150g/l, the temperature is 100 ℃, and the running speed of the steel belt is 15 m/min; the surfactant comprises the following components in percentage by weight: carboxymethyl cellulose: 15%, biochemical fulvic acid: 5%, 2-aminoethanol: 20%, 8-hydroxyquinoline-5-sulfonic acid: 10%, water: 50 percent; the sulfuric acid is used for removing residual oxide skin through oxidation-reduction reaction, and the surfactant is used for destroying metal bonds between the oxide skin and a matrix and improving the pickling efficiency of the sulfuric acid;
(V) brushing: the steel belt coming out of the sulfuric acid pickling tank enters a brushing tank, the length of the brushing tank is 7m, the medium is industrial soft water, the sulfuric acid solution and the surfactant remaining on the surface of the steel belt are brushed under the action of a brush roller, and after the brushing is finished, water stains on the surface of the steel belt are squeezed by a squeezing roller;
(VI) passivating by nitric acid: the steel strip discharged from the brushing groove enters a nitric acid passivation groove for passivation, the length of the nitric acid passivation groove is 18m, the concentration of nitric acid is 180g/l, and the temperature is 20 ℃, so that the steel strip is fully passivated;
(VII) final cleaning and drying: the final cleaning tank is divided into two sections, one section is a final cleaning section, the other section is a drying section, and the rear side of the final cleaning tank is provided with a tensioning machine; the steel belt from the nitric acid passivation tank sequentially passes through a final cleaning section, a drying section and a tensioning machine of the final cleaning tank, the length of the final cleaning section of the final cleaning tank is 10m, the medium is industrial soft water, the residual nitric acid solution on the surface of the steel belt is scrubbed under the action of a brush roll, the residual nitric acid solution on the surface of the steel belt is prevented from causing transitional pickling, water stains on the surface of the steel belt are squeezed by a squeezing roll, and the steel belt passes through the drying section and is dried by hot air through steam, so that the surface of the steel belt is prevented from being polluted in the subsequent operation; the dried steel strip enters a rear loop to wait for curling, and the length of the rear loop is 400 meters;
(eighth), winding: and (4) feeding the steel strip which comes out from the rear loop into a coiling machine for coiling operation, and cutting two ends of a welding line through a slitting shear when the steel strip is coiled to the tail of the strip to obtain a finished product of the 400-series stainless steel pickled steel coil.
The pickled steel strip is detected on line before curling, and the apparent quality of the pickled steel strip is qualified by detecting that the surface of the steel strip has no defects of under-pickling, residual iron scale, under-pickling, over-pickling, acid spots and the like.
Claims (2)
1. A continuous production method of 400 series stainless steel hot rolled steel strip by fluorine-free acid cleaning is characterized in that: it comprises the following steps:
(I) uncoiling: after a 400 series stainless steel hot rolled steel coil is uncoiled by an uncoiler, a strip head and the strip tail of the previous coil are cut and leveled by a double-edge guillotine type shearing machine, and then the welding is carried out by an MIG argon arc welding machine, so that the adjacent coils are connected into a continuous steel strip; in order to ensure the welding quality, the thickness difference of steel coils at two ends of a welding seam is required to be less than 3 mm; the welded steel strip enters a front loop, and the length of the front loop is 500 meters;
(II) scale breaking: the front and the back of the scale breaker are respectively provided with a tensioning machine, and under the tension action of the tensioning machines, the steel belt out of the front loop sequentially passes through the tensioning machine at the front side, the scale breaker and the tensioning machine at the back side; the rolling reduction of a bending roller of the scale breaker is less than or equal to 75 mm, and the rolling reduction of a straightening roller is less than or equal to 80 mm; properly adjusting the production tension of the tensioning machine according to the thickness of the steel strip to ensure that the outlet tension of the scale breaker meets the requirement and ensure that the elongation of the steel strip is more than 1.2 percent; the requirements for controlling the outlet tension of the scale breaker are shown in table 1;
table 1:
(III) shot blasting: the front and the back of the shot blasting machine are respectively provided with a tensioning machine, under the tension action of the tensioning machines, the steel belt sequentially passes through the tensioning machine on the front side, the shot blasting machine and the tensioning machine on the back side, and shot blasting treatment is carried out on the surface of the steel belt through the shot blasting machines; the shot blasting machine adopts a mixed abrasive of steel shots and steel grits, the grain sizes of the steel shots and the steel grits are 0.3-0.5 mm, and the weight ratio of the steel shots to the steel grits is 3: 7; in the production process, the shot blasting machine is provided with two units, the rotating speed and the sand discharge amount of a throwing head are controlled by throwing head current, the throwing head current is controlled according to the thickness of a steel strip, and the requirement of the throwing head current control is shown in a table 2;
table 2:
(IV) sulfuric acid pickling: a tensioning machine is arranged on the front side of the sulfuric acid pickling tank, the steel strip is conveyed into the sulfuric acid pickling tank under the tension action of the tensioning machine for sulfuric acid pickling, the length of the sulfuric acid pickling tank is 22m, and a surfactant is added into the sulfuric acid solution; wherein the concentration of the surfactant is 10-50 g/l, the concentration of the sulfuric acid is 150-280 g/l, and the temperature is 60-100 ℃; adjusting the running speed of the steel strip according to the thickness of the steel strip and the concentration of sulfuric acid and surfactant, wherein the range is 15-40 m/min; the surfactant comprises the following components in percentage by weight: carboxymethyl cellulose: 10-15%, biochemical fulvic acid: 3-5%, 2-aminoethanol: 20-40%, 8-hydroxyquinoline-5-sulfonic acid: 5-10%, water: 42-50%;
(V) brushing: the steel belt coming out of the sulfuric acid pickling tank enters a brushing tank, the length of the brushing tank is 7m, the medium is industrial soft water, the sulfuric acid solution and the surfactant remaining on the surface of the steel belt are brushed under the action of a brush roller, and after the brushing is finished, water stains on the surface of the steel belt are squeezed by a squeezing roller;
(VI) passivating by nitric acid: the steel strip discharged from the brushing groove enters a nitric acid passivation groove for passivation, the length of the nitric acid passivation groove is 18m, the concentration of nitric acid is 100-180 g/l, and the temperature is 20-50 ℃, so that the steel strip is fully passivated;
(VII) final cleaning and drying: the final cleaning tank is divided into two sections, one section is a final cleaning section, the other section is a drying section, and the rear side of the final cleaning tank is provided with a tensioning machine; the steel belt from the nitric acid passivation tank sequentially passes through a final cleaning section, a drying section and a tensioning machine of the final cleaning tank, the length of the final cleaning section of the final cleaning tank is 10m, the medium is industrial soft water, the residual nitric acid solution on the surface of the steel belt is scrubbed under the action of a brush roll, the residual nitric acid solution on the surface of the steel belt is prevented from causing transitional pickling, water stains on the surface of the steel belt are squeezed by a squeezing roll, and the steel belt passes through the drying section and is dried by hot air through steam, so that the surface of the steel belt is prevented from being polluted in the subsequent operation; the dried steel strip enters a rear loop to wait for curling, and the length of the rear loop is 400 meters;
(eighth), winding: and (4) feeding the steel strip which comes out from the rear loop into a coiling machine for coiling operation, and cutting two ends of a welding line through a slitting shear when the steel strip is coiled to the tail of the strip to obtain a finished product of the 400-series stainless steel pickled steel coil.
2. A surfactant special for fluorine-free acid cleaning of 400 series stainless steel hot rolled steel strips is characterized in that: the composite material comprises the following components in percentage by weight: carboxymethyl cellulose: 10-15%, biochemical fulvic acid: 3-5%, 2-aminoethanol: 20-40%, 8-hydroxyquinoline-5-sulfonic acid: 5-10%, water: 42-50%.
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| CN111993216A (en) * | 2020-07-02 | 2020-11-27 | 山西太钢不锈钢股份有限公司 | Method for manufacturing duplex stainless steel hot-rolled middle plate with surface roughness Ra less than or equal to 5 mu m |
| CN112620359A (en) * | 2020-12-15 | 2021-04-09 | 文春鱼 | Acid-free shot blasting rust removal process for hot-rolled steel coil |
| CN112779548A (en) * | 2020-12-27 | 2021-05-11 | 山东盛阳金属科技股份有限公司 | 300-series stainless steel plate pickling system and pickling process thereof |
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