Classifications

• • 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
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
  • B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
  • B21B45/0203—Cooling
  • B21B45/0206—Coolants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
  • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
  • B21B2001/228—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length skin pass rolling or temper rolling

Definitions

• the invention relates to wet work hardening of steel sheet metal.
• sheet hardening is understood to mean the work of a sheet, in particular for crushing or deforming it.
• a steel sheet is generally subjected to recrystallization annealing and then to work hardening.
• the purpose of the work hardening is to improve the mechanical characteristics and the flatness of the sheet and to imprint a predetermined roughness on its surface.
• This work hardening is generally carried out continuously by passage and moderate crushing of the sheet between two cylinders.
• the work hardening step can be carried out in the wet phase, that is to say under spraying with a work hardening treatment solution.
• the work hardening treatment solution is generally sprayed on both sides of the sheet at the level of the sheet grip between the two cylinders.
• the sheet After wet work hardening, the sheet is generally dried, then possibly oiled and, in the case of strip sheet, rewound.
• these inhibitors must be adapted to also resist atmospheric corrosion, which is different from corrosion in a submerged environment, and to resist high work hardening pressures.
• Corrosion inhibitors commonly used for this application are based on nitrites or organic products such as amine borates.
• nitrites For nitrites, they cannot be removed from the effluents by conventional treatments, such as those used to treat effluents from laminating plants, which are generally flocculation treatments.
• the object of the invention is to provide an aqueous solution for treating work hardening of steel sheets offering satisfactory protection against corrosion, including atmospheric corrosion, presenting no particular danger and generating effluents which are easy and economical to treat.
• Satisfactory protection against corrosion means protection at least equivalent to that obtained with conventional solutions of the prior art, commonly used for this application.
• economic effluents to be treated is understood to mean effluents which can be treated in a conventional manner, in particular according to a conventional method for treating rolling effluents, while respecting the admissible discharge standards in force.
• welded steel tubes For the manufacture of welded steel tubes, we start from slitted steel sheets over a width corresponding to the diameter of the tubes to be manufactured, then a tubular cylindrical envelope is formed by successive passes of routing and forming the sheet between rollers, welded longitudinally to close the envelope thus formed, then, after any calibration and ultimate profiling, the tube is cut and the tubes cut into bundles.
• the sheet should be sprinkled with a work hardening fluid allowing, in particular, to cool the sheet or the tube (as well as the rollers of the installation).
• the work hardening of the sheet is therefore also carried out in a humid environment and there are also problems of atmospheric corrosion, in particular during the storage of the tubes (in bundles), and in particular at the points of contact of the tubes with one another. same boot.
• a disadvantage of these work hardening solutions is that fatty tubes are obtained on the surface, and that it is then advisable to degrease them if it is desired, for example, to paint them or coat them.
• the object of the invention is therefore to provide an aqueous solution for the work hardening of steel sheets providing satisfactory protection against corrosion without giving a greasy appearance and making it possible to economize on the degreasing operation, in the event of including coating or painting.
• the subject of the invention is an aqueous treatment solution for wet work hardening of steel sheets, characterized in that it contains a water-soluble salt of heptanoic acid and an oxidizing agent.
• Soluble salts of heptanoic acid are already known as compounds which inhibit metallic corrosion in a submerged medium, in particular in cooling circuits.
• an aqueous solution of heptanoic acid salts can also be used as work hardening solution, because these salts resist high work hardening pressures and also provide resistance to atmospheric corrosion.
• the sheet metal treated with this solution does not have a greasy appearance and it is often not even necessary to degrease it for subsequent operations, for example coating or painting.
• the effluents of this solution are easier to treat.
• Effluent treatment is further facilitated due to the biodegradable nature of the heptanoic acid salts.
• Another advantage of the invention is that these solutions do not present any risk with regard to public health.
• the example which follows relates to the work hardening of sheets at the end of rolling.
• the work hardening device is of a conventional type and comprises two superimposed work hardening cylinders and the path of travel of the sheet metal strip to be hardened is approximately horizontal and passes between the rolls.
• the device At the level of the strip-cylinder grip, on the travel path, the device comprises spray nozzles for uniformly spraying the lower and upper surfaces of a moving strip.
• These spray nozzles are connected by pumps to a tank of aqueous work hardening treatment solution.
• the work hardening device also includes means for recovering the treatment solution arranged under the running path and connected to a treatment and purification station for waste water.
• an aqueous solution which, according to the invention, contains sodium heptanoate as water-soluble salt of heptanoic acid and sodium perborate as oxidant.
• the pH of the solution is adjusted to a value close to 9, for example by adding sodium hydroxide.
• the molar concentration of sodium heptanoate is less than or equal to 5 10 -2 mole per liter; in practice, this concentration will generally be greater than 10 -3 mole / liter.
• the molar concentration of sodium perborate is approximately less than or equal to the molar concentration of sodium heptanoate; in practice, this concentration will generally be greater than or equal to about one tenth of this concentration.
• a strip of sheet steel is worked continuously by spraying the lower and upper surfaces of the strip with the treatment solution according to the invention. 'invention.
• the effluents of the solutions according to the invention are also easier to treat than the solutions of the prior art based on nitrites.
• a wetting agent is added to the work hardening solution according to the invention.
• the wetting agent is of the nonionic type; its concentration is about 0.1%.
• wetting agent a product marketed by the company WITCO under the trade name PA 9017, or a product marketed by the company HENKEL under the name of MAGNUSPRAY (wetting agent of the family of polyethoxylated alcohols).
• the function of the wetting agent is to spread the treatment solution evenly over the surface of the sheet to obtain a protective and passivating layer of constant thickness.
• wetting agent in the work hardening solution according to the invention makes it possible to further lower the heptanoic acid salt and oxidant concentrations which are sufficient to obtain satisfactory resistance to corrosion. , which allows effluent to be treated even more easily and economically.
• the molar concentration of sodium heptanoate will then be less than or equal to 2 10 -2 moles per liter.
• wetting agents are particularly advantageous when it is planned to then oil the sheet to protect it against corrosion in the longer term: in fact, this type of wetting agent does not disturb the possible subsequent spreading of the oil film.
• anti-foam products can be added to the treatment solution to limit the formation of foam during work hardening.
• the work hardening solution according to the invention can be used in other sheet hardening operations, in particular for the manufacture of welded tubes.
• the solution according to the invention has been used successfully for the manufacture of tubes from steel sheets, in particular "black” steel, raw pickling or cold rolling steel or aluminized steel.
• the pH of the hardening solution can be adjusted according to the type of coating of the steel.
• the tubes obtained do not have a greasy appearance and can be painted without prior degreasing.
• Tubes stored in bundles are very resistant to corrosion (even on the contact area between the tubes of the same bundle).
• TOC total organic carbon
• WAC aluminum salt from the company ATOCHEM
• This product generally has the effect of flocculating very dilute compounds present in the effluents by entraining part of the carbon contained in a solid phase which is easily separated.
• This product is used in a conventional manner to treat the effluents of rolling installations, installations which are frequently found upstream of the work hardening installations.
• the treatability of the effluents is therefore significantly improved (here by more than 40%).
• the purpose of this example is to illustrate the corrosion protection performance of treatment solutions according to the invention containing sodium heptanoate (designated by NaC7) and an oxidizing agent (sodium perborate - NaBO2, H2O2, 3H2O, designated by "Ox1").
• the molar concentration of oxidant must remain less than or equal to the molar concentration of corrosion inhibitor, here sodium heptanoate.
• a molar concentration of oxidizer of only about one tenth of that of the corrosion inhibitor may suffice.
• the purpose of this example is to illustrate the corrosion protection performance of the work hardening treatment solutions according to the invention compared with those of solutions of the prior art, in particular based on nitrites or organic products such as borates. amine, under conditions approaching those of the intended application.
• NaC7 denotes sodium heptanoate.
• 100 mm ⁇ 100 mm steel sheet samples are prepared, a series of work hardening treatment solutions to be tested and a series of corrosive solutions of sodium sulphate at different concentrations.
• Comparative series n ° 1 sodium nitrite.
• Corrosive Treatment solution sodium nitrite - g / l Na2SO4 g / l 0.0 g / l 2.5 g / l 3.0 g / l 5.0 g / l 6.5 g / l 0.0 g / l R R P B B 0.5 g / l R R P B B 5.0 g / l R R R R R R R R R R Comparative series n ° 2: organic liquid of the prior art.
• the liquid used here is sold under the reference N272 by the company QUAKER; it contains in particular amine borate. Ground. corrosive Ground.
• "organic" treatment diluted quantity - g / l Na2SO4 g / l 0.5 1.5 3 5 0.0 g / l B B B B 0.5 g / l B B B B 5.0 g / l R R R R Comparative series n ° 3: liquid containing nitrites according to the prior art.
• the liquid used here is sold under the reference 508DR by the company QUAKER; it contains in particular nitrites. Ground. corrosive Ground.
• This example is intended to illustrate the implementation of the invention, in particular when a wetting agent is added to the solutions described above of sodium heptanoate and of oxidant.
• the oxidant used here for the test is a sodium nitrite, designated below by "Ox2".
• a wetting agent makes it possible to further reduce the concentrations of heptanoic acid salt and of oxidizing agent necessary to obtain both satisfactory protection against corrosion and effluents which are easy and economical to treat.
• Example 3 which concluded that a sufficient concentration of the order of 0.05 mole / liter of heptanoic acid salt in a solution without wetting agent (but with oxidant), one could even obtain sufficient corrosion resistance with a concentration of only 0.02 mole / liter of heptanoic acid salt in a solution with wetting agent (and always with oxidant).

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Preventing Corrosion Or Incrustation Of Metals (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Heat Treatment Of Strip Materials And Filament Materials (AREA)
• Lubricants (AREA)

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• 1995
  • 1995-12-07 FR FR9514440A patent/FR2742080B1/fr not_active Expired - Fee Related
• 1996
  • 1996-10-30 EP EP96402301A patent/EP0778091B1/de not_active Expired - Lifetime
  • 1996-10-30 AT AT96402301T patent/ATE188895T1/de not_active IP Right Cessation
  • 1996-10-30 PT PT96402301T patent/PT778091E/pt unknown
  • 1996-10-30 DE DE69606270T patent/DE69606270T2/de not_active Expired - Fee Related
  • 1996-10-30 ES ES96402301T patent/ES2143162T3/es not_active Expired - Lifetime
  • 1996-12-03 CA CA002191938A patent/CA2191938A1/fr not_active Abandoned
  • 1996-12-06 JP JP8342760A patent/JPH09194873A/ja not_active Withdrawn
  • 1996-12-09 US US08/760,671 patent/US5814247A/en not_active Expired - Fee Related

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