CN103820842A - Pickling method for surface of austenitic stainless steel before cold bending - Google Patents
Pickling method for surface of austenitic stainless steel before cold bending Download PDFInfo
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- CN103820842A CN103820842A CN201410059489.XA CN201410059489A CN103820842A CN 103820842 A CN103820842 A CN 103820842A CN 201410059489 A CN201410059489 A CN 201410059489A CN 103820842 A CN103820842 A CN 103820842A
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Abstract
The invention relates to a pickling method for a surface of austenitic stainless steel before cold bending, and belongs to the technical field of stainless steel surface treatment. The pickling method is characterized in that firstly, an alkaline chemical method is used to remove oil before pickling and a plurality of surfactants are added to improve oil-removing and cleaning effects; during the pickling process, a process combining neutral salts and acid solutions is adopted to reduce pickling cost; hydrochloric acid and sulfuric acid are used to replace a nitric acid solution in a conventional process and additives such as the surfactants and corrosion inhibitors are added to improve the pickling effect; and finally the pickling process combining water washing and neutral salt washing is adopted to remove chloride ions left by previous steps thoroughly. By picking the austenitic stainless steel before cold bending with the method, oxide skins on the surface of the austenitic stainless steel can be removed effectively; metal glossiness of the austenitic stainless steel can be improved; and corrosion resistance of the austenitic stainless steel is improved.
Description
Technical field
The acid washing method that the present invention relates to a kind of austenitic stainless steel clod wash front surface, belongs to stainless steel surface processing technology field.
Background technology
In recent years, austenitic stainless steel had been used widely aspect urban track traffic and high-speed railway because of its good outward appearance and excellent solidity to corrosion.At present, railway transportation equipment is mainly manufactured by cold bending technique by austenite stainless shaped steel.Can there is thicker oxide skin at cold bending front surface in stainless steel, not only affect stainless visual appearance, also can have a negative impact to its cold-bending property, as produced the phenomenons such as cold bend cracking.Therefore before clod wash, must remove its surface scale through overpickling.For Austenitic, martensite type, ferrite type and duplex stainless steel etc., due to its structural constituent difference, acid cleaning process is also not quite similar.For austenitic stainless steel, through processing rear oxidation outer cortex, take ferriferous oxide as main, internal layer is take dense form oxide compounds such as siderochrome oxide compounds as main.Current different types of stainless steel all adopts identical acid cleaning process, and while removing stainless steel surface heavy scale, use temperature is high, and pickling time is long, and tooling cost remains high; And normal temperature acid cleaning process is to effective except thin oxide skin, and stainless steel cold-rolled plate after pickling surface obfuscation, has lost original metalluster, can not meet the requirement of railway transportation equipment.
It is generally acknowledged, austenitic stainless steel adopts the solution pickling effect that aggressiveness is stronger better.While adopting salpeter solution pickling austenitic stainless steel, scale removal preferably, stainless steel metal gloss is obvious.But this technique can produce nitrous acid steam, harmful to human body and environment.Due to the requirement of environmental protection, this technique has been subject to more and more stricter restriction.Developed in recent years many " without nitric acid acidwashing technique ", and in pickle solution, added the mineral acid such as hydrochloric acid and sulfuric acid to replace original salpeter solution.Though can meet the requirement of environmental protection, but when after the solution pickling of stainless steel with hydrochloric, chlorion is adsorbed by stainless steel surface, be preferentially adsorbed on metal passivation film, and being combined into soluble chloride with the positively charged ion in passive film, result generates spot corrosion core on the metallic matrix exposing, and in medium under the promoter action of cation oxidant, more than corrosion of metal current potential rises to spot corrosion critical potential, and then form pit.Particularly, railway transportation equipment adds man-hour with austenitic stainless steel in clod wash, has formed the structure of large negative electrode-primary anode in geometric shape, and the anode dissolution speed of spot corrosion is accelerated; Meanwhile, owing to thering is automatic acceleration in Pitting Propagation, will cause very soon stainless corrosion failure to destroy.This safety for railway transportation equipment produces serious harm.Therefore, the existence of chlorion makes stainless steel corrosion-vulnerable, has affected stainless steel and has been applied to the solidity to corrosion in track traffic, so must remove chlorion in acid cleaning process.
Summary of the invention
In order to overcome the deficiency of acid cleaning process aspect before existing austenitic stainless steel clod wash, and the disadvantageous effect of more thoroughly avoiding chlorion to bring stainless steel solidity to corrosion, the invention provides a kind of acid washing method of removing austenitic stainless steel surface scale and improving its surface metal glossiness.Concrete grammar comprises the following steps:
Step 1, by annealing after austenitic stainless steel carry out electrochemical deoiling by a pickling tank, scavenging solution formula in a pickling tank is: the sodium carbonate of concentration 15-40g/L, the OP-10 emulsifying agent of concentration 3-6g/L, the Seconary Alkane Sulphonate Sodium of concentration 2-5g/L, the sodium lauryl sulphate of concentration 2-4g/L, controlling temperature is 80 ± 10 ℃, and soak time is 2-3min;
Step 2, by austenitic stainless steel by No. two pickling tanks, the medium of No. two pickling tanks is water, temperature is 50-70 ℃, soak time is 2-3min;
Step 3, by austenitic stainless steel by an electrolyzer, the medium of an electrolyzer is metabisulfite solution, strength of solution is 10 ~ 25%, current density is 12 ~ 20A/dm
2, electrolysis time is 30s ~ 60s;
Step 4, by austenitic stainless steel by No. two electrolyzers, the medium of No. two electrolyzers is metabisulfite solution, strength of solution is 10 ~ 25%, current density is 12 ~ 20A/dm
2, electrolysis time is 30s ~ 60s;
Step 5, by austenitic stainless steel by No. three electrolyzers, current density is 10 ~ 20A/dm
2, it is 45-55 ℃ that front 10 ~ 15min controls pickling temperature, it is 25-35 ℃ that rear 15 ~ 20min controls pickling temperature; Wherein the solution formula of No. three electrolyzers is: the hydrochloric acid of concentration 280-320 ml/ L, the sulfuric acid of 90-110 ml/ L, the hydrogen peroxide of 70-80 ml/ L, ethylene glycol/acetic acid built agent of 45-55 ml/ L, the polyoxyethylene octyl phenolic ether of 2-5ml/L, the APG of 2-5ml/L; Wherein in ethylene glycol/acetic acid built agent, quality of glycol accounts for 55 ~ 70%, and quality of acetic acid accounts for 30 ~ 45%;
Step 6, by austenitic stainless steel by No. three pickling tanks, the medium of No. three pickling tanks is water, temperature is 40-50 ℃, soak time is 1-2min, soaking number of times is 2-3 time;
Step 7, by austenitic stainless steel by No. four pickling tanks, the medium of No. four pickling tanks is metabisulfite solution, strength of solution is 25-50%, temperature is 65-75 ℃, soak time is 2-3min.
In step 1, OP-10 emulsifying agent and Seconary Alkane Sulphonate Sodium are tensio-active agent, and sodium lauryl sulphate is dispersion agent.OP-10 emulsifying agent has wetting and emulsifying effect preferably, and Seconary Alkane Sulphonate Sodium has good penetrating power, is green additive, and sodium lauryl sulphate, as dispersion agent, can improve and improve the dispersiveness of greasy dirt in liquid.The use of these additives all can be accelerated oil removing process.
In step 2, washing reaches the effect of clean surface.
Step 3 and step 4 are to adopt neutral salt pickling austenitic stainless steel, and main purpose is to remove take ferriferous oxide as main outer oxide skin.
Step 5 is to use the stronger acid solution pickling austenitic stainless steel of aggressiveness, and object is further to remove surperficial grey film, removes take dense form oxide compounds such as siderochrome oxide compounds as main internal layer oxide skin simultaneously.In this electrolyzer except formed acid stronger solution by hydrochloric acid and sulfuric acid, also added hydrogen peroxide oxidant, hydrogen peroxide has very strong oxidisability, the compound structure that can make austenitic stainless steel surface be insoluble in pickle solution changes, but hydrogen peroxide is unstable, the present invention adds ethylene glycol/acetic acid built agent as stablizer in solution, plays Stabilizing Hydrogen Peroxide, improves pickling effect.Meanwhile, add a small amount of polyoxyethylene octyl phenolic ether and APG as tensio-active agent and inhibiter, both accelerated acid cleaning process, also prevent the disadvantageous effect that chlorion brings.This acid cleaning process is the step of whole austenitic stainless steel except descaling most critical, and wherein the control of temperature is also very important.If pickling temperature is inadequate, the compactness oxide skin of internal layer is difficult to come off, and needs long pickling, has wasted tooling cost.If but keep for a long time higher temperature, and by accelerating the infiltration of chlorion, destroy stainless passivation layer, cause its solidity to corrosion to decline.Therefore, the present invention adopts segmentation control temperature method, and front 10 ~ 15min takes comparatively high temps pickling of stainless steel, and the siderochrome oxide skin of acceleration internal layer etc. comes off, and after oxide skin comes off completely, reduces pickling temperature, to reduce the destruction of chlorion.
Step 6 is that austenitic stainless steel is soaked in washing in order to remove chlorion under residual of operation above and not introduce new chlorion.
Step 7 is to adopt neutral salt soaking technology, to remove up hill and dale chlorion, promotes stainless solidity to corrosion.
The present invention can remove the oxide skin that austenitic stainless steel surface forms in the time of annealing, so that cold roll forming.The clean light of stainless steel surface after processing, have not loss of gloss, colour-fast, be difficult for the advantages such as yellowing, pickle solution, containing nitric acid, produces without tobacco, meets the requirement of environmental protection.
Embodiment
Describe the embodiment of the acid washing method of this austenitic stainless steel clod wash front surface in detail below in conjunction with embodiment, but the embodiment of the acid washing method on this austenitic stainless steel surface is not limited to following embodiment.
Embodiment mono-
The present embodiment pickling be annealing after 301L stainless steel, its step is as follows:
(1) austenitic stainless steel after annealing is passed through to a pickling tank, the medium of a pickling tank is the sodium carbonate solution of 30g/L, adds OP-10 emulsifying agent 4g/L, Seconary Alkane Sulphonate Sodium 3g/L, sodium lauryl sulphate 3g/L, pickling temperature is 80 ℃, pickling time is 3min;
(2) austenitic stainless steel is passed through to No. two pickling tanks, the medium of second pickling tank is water, and temperature is 60 ℃, and soak time is 3min;
(3) austenitic stainless steel is passed through to an electrolyzer, the medium of an electrolyzer is metabisulfite solution, and strength of solution is 20%, and current density is 15A/dm
2, electrolysis time is 40s;
(4) austenitic stainless steel is passed through to No. two electrolyzers, the medium of No. two electrolyzers is metabisulfite solution, and strength of solution is 20%, and current density is 15A/dm
2, electrolysis time is 40s;
(5) austenitic stainless steel is passed through to No. three electrolyzers, the medium of No. three electrolyzers is hydrochloric acid 300 ml/L, sulfuric acid 100ml/L, hydrogen peroxide 75 ml/L, ethylene glycol/acetic acid built agent 50ml/L (ethylene glycol 60%, acetic acid 40%), polyoxyethylene octyl phenolic ether 4ml/L, APG 3ml/L, current density is 15A/dm
2, front 15min electrolysis temperature is 50 ℃, rear 15min electrolysis temperature is 30 ℃;
(6) austenitic stainless steel is passed through to No. three pickling tanks, the medium of No. three pickling tanks is water, and temperature is 45 ℃, and soak time is 2min, and soaking number of times is 3 times;
(7) austenitic stainless steel is passed through to No. four pickling tanks, the medium of No. four pickling tanks is metabisulfite solution, and strength of solution is 30%, and temperature is 70 ℃, and soak time is 3min.
After the present embodiment pickling, 301L stainless steel surface is uniform silvery white, after testing, the corrosion-free vestige of stainless steel surface, the pH value that checks stainless steel surface washing fluid with phenolic aldehyde test paper is 7, by in turbidimetry for Determination stainless steel surface washing fluid, chloride ion content is lower than 0.4mg/L, its solidity to corrosion is obviously better than before pickling.
Embodiment bis-
The present embodiment pickling be annealing after 304 stainless steels, its step is as follows:
(1) austenitic stainless steel after annealing is passed through to a pickling tank, the medium of a pickling tank is the sodium carbonate solution of 40g/L, adds OP-10 emulsifying agent 6g/L, Seconary Alkane Sulphonate Sodium 5g/L, sodium lauryl sulphate 4g/L, pickling temperature is 90 ℃, pickling time is 3min;
(2) austenitic stainless steel is passed through to No. two pickling tanks, the medium of No. two pickling tanks is water, and temperature is 70 ℃, and soak time is 2min;
(3) austenitic stainless steel is passed through to an electrolyzer, the medium of an electrolyzer is metabisulfite solution, and strength of solution is 25%, and current density is 20A/dm
2, electrolysis time is 60s;
(4) austenitic stainless steel is passed through to No. two electrolyzers, the medium of No. two electrolyzers is metabisulfite solution, and strength of solution is 25%, and current density is 20A/dm
2, electrolysis time is 60s;
(5) austenitic stainless steel is passed through to No. three electrolyzers, the medium of No. three electrolyzers is hydrochloric acid 320ml/L, sulfuric acid 110 ml/L, hydrogen peroxide 80 ml/L, ethylene glycol/acetic acid built agent 55ml/L(ethylene glycol 65%, acetic acid 35%), polyoxyethylene octyl phenolic ether 5ml/L, APG 5ml/L, current density is 20A/dm
2, front 15min electrolysis temperature is 55 ℃, rear 15min electrolysis temperature is 25 ℃;
(6) austenitic stainless steel is passed through to No. three pickling tanks, the medium of No. three pickling tanks is water, and temperature is 50 ℃, and soak time is 2min, and soaking number of times is 2 times;
(7) austenitic stainless steel is passed through to No. four pickling tanks, the medium of No. four pickling tanks is Na
2sO
4solution, strength of solution is 50%, and temperature is 75 ℃, and soak time is 3min.
After the present embodiment pickling, 304 stainless steel surface are uniform silvery whites, after testing, the corrosion-free vestige of stainless steel, the pH value that checks stainless steel surface washing fluid with phenolic aldehyde test paper is 7, by in turbidimetry for Determination stainless steel surface washing fluid, chloride ion content is lower than 0.4mg/L, its solidity to corrosion is better than before pickling.
Embodiment tri-
The present embodiment pickling be annealing after 316 stainless steels, its step is as follows:
(1) austenitic stainless steel after annealing is passed through to a pickling tank, the medium of a pickling tank is the sodium carbonate solution of 15g/L, adds OP-10 emulsifying agent 3g/L, Seconary Alkane Sulphonate Sodium 2g/L, sodium lauryl sulphate 2g/L, pickling temperature is 70 ℃, pickling time is 3min;
(2) austenitic stainless steel is passed through to No. two pickling tanks, the medium of No. two pickling tanks is water, and temperature is 50 ℃, and soak time is 2min;
(3) austenitic stainless steel is passed through to an electrolyzer, the medium of an electrolyzer is metabisulfite solution, and strength of solution is 10%, and current density is 12A/dm
2, electrolysis time is 30s;
(4) austenitic stainless steel is passed through to No. two electrolyzers, the medium of No. two electrolyzers is metabisulfite solution, and strength of solution is 10%, and current density is 12A/dm
2, electrolysis time is 30s;
(5) austenitic stainless steel is passed through to No. three electrolyzers, the medium of No. three electrolyzers is hydrochloric acid 280ml/L, sulfuric acid 90 ml/L, hydrogen peroxide 70 ml/L, ethylene glycol/acetic acid built agent 45 ml/L(ethylene glycol 65%, acetic acid 35%), polyoxyethylene octyl phenolic ether 2ml/L, APG 2ml/L, current density is 10A/dm
2, front 15min electrolysis temperature is 45 ℃, rear 15min electrolysis temperature is 25 ℃;
(6) austenitic stainless steel is passed through to No. three pickling tanks, the medium of No. three pickling tanks is water, and temperature is 40 ℃, and soak time is 1min, and soaking number of times is 2 times;
(7) austenitic stainless steel is passed through to No. four pickling tanks, the medium of No. four pickling tanks is metabisulfite solution, and strength of solution is 25%, and temperature is 65 ℃, and soak time is 2min.
After the present embodiment pickling, 316 stainless steel surface are uniform silvery whites, after testing, stainless steel surface is without obvious evidence of corrosion, phenolic aldehyde test paper checks that the pH value of stainless steel surface washing fluid is 7, by in turbidimetry for Determination stainless steel surface washing fluid, chloride ion content is lower than 0.4mg/L, its solidity to corrosion is obviously better than before pickling.
Claims (1)
1. the acid washing method before austenitic stainless steel clod wash, is characterized in that comprising following process:
Step 1, by annealing after austenitic stainless steel carry out electrochemical deoiling by a pickling tank, scavenging solution formula in a pickling tank is: the sodium carbonate of concentration 15-40g/L, the OP-10 emulsifying agent of concentration 3-6g/L, the Seconary Alkane Sulphonate Sodium of concentration 2-5g/L, the sodium lauryl sulphate of concentration 2-4g/L, controlling temperature is 80 ± 10 ℃, and soak time is 2-3min;
Step 2, by austenitic stainless steel by No. two pickling tanks, the medium of No. two pickling tanks is water, temperature is 50-70 ℃, soak time is 2-3min;
Step 3, by austenitic stainless steel by an electrolyzer, the medium of an electrolyzer is metabisulfite solution, strength of solution is 10 ~ 25%, current density is 12 ~ 20A/dm
2, electrolysis time is 30s ~ 60s;
Step 4, by austenitic stainless steel by No. two electrolyzers, the medium of No. two electrolyzers is metabisulfite solution, strength of solution is 10 ~ 25%, current density is 12 ~ 20A/dm
2, electrolysis time is 30s ~ 60s;
Step 5, by austenitic stainless steel by No. three electrolyzers, current density is 10 ~ 20A/dm
2, it is 45-55 ℃ that front 10 ~ 15min controls pickling temperature, it is 25-35 ℃ that rear 15 ~ 20min controls pickling temperature; Wherein the solution formula of No. three electrolyzers is: the hydrochloric acid of concentration 280-320 ml/ L, the sulfuric acid of 90-110 ml/ L, the hydrogen peroxide of 70-80 ml/ L, ethylene glycol/acetic acid built agent of 45-55 ml/ L, the polyoxyethylene octyl phenolic ether of 2-5ml/L, the APG of 2-5ml/L; Wherein in ethylene glycol/acetic acid built agent, quality of glycol accounts for 55 ~ 70%, and quality of acetic acid accounts for 30 ~ 45%;
Step 6, by austenitic stainless steel by No. three pickling tanks, the medium of No. three pickling tanks is water, temperature is 40-50 ℃, soak time is 1-2min, soaking number of times is 2-3 time;
Step 7, by austenitic stainless steel by No. four pickling tanks, the medium of No. four pickling tanks is metabisulfite solution, strength of solution is 25-50%, temperature is 65-75 ℃, soak time is 2-3min.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105506725A (en) * | 2015-12-17 | 2016-04-20 | 天津市富仁板带有限公司 | Steel strip degreasing process |
| CN107502900A (en) * | 2017-09-11 | 2017-12-22 | 苏州盈腾五金制品有限公司 | A kind of ultrasonic wave acid cleaning process of cast iron hardware |
| CN114045377A (en) * | 2022-01-07 | 2022-02-15 | 北京煜鼎增材制造研究院有限公司 | Laser phase change strengthening method for surface of medium carbon steel |
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| CN103014732A (en) * | 2013-01-07 | 2013-04-03 | 常州市卯旺化工有限公司 | Environmentally-friendly steel oil and rust removing solution at normal temperature |
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| CN101165223A (en) * | 2007-08-15 | 2008-04-23 | 山西太钢不锈钢股份有限公司 | Acid pickling method for stainless steel surface |
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| CN103014732A (en) * | 2013-01-07 | 2013-04-03 | 常州市卯旺化工有限公司 | Environmentally-friendly steel oil and rust removing solution at normal temperature |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105506725A (en) * | 2015-12-17 | 2016-04-20 | 天津市富仁板带有限公司 | Steel strip degreasing process |
| CN105506725B (en) * | 2015-12-17 | 2018-05-25 | 天津市富仁板带有限公司 | A kind of steel tape degreasing technique |
| CN107502900A (en) * | 2017-09-11 | 2017-12-22 | 苏州盈腾五金制品有限公司 | A kind of ultrasonic wave acid cleaning process of cast iron hardware |
| CN114045377A (en) * | 2022-01-07 | 2022-02-15 | 北京煜鼎增材制造研究院有限公司 | Laser phase change strengthening method for surface of medium carbon steel |
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Application publication date: 20140528 |