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 crush or deform it.
• a steel sheet is generally subjected to recrystallization annealing and then to work hardening.
• the purpose of work hardening is to improve the mechanical characteristics and the flatness of the sheet and to print 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, i.e. under spraying with a work hardening treatment solution.
• the work hardening treatment solution is generally sprayed on the two faces of the sheet at the level of the grip of the sheet 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 the atmospheric corrosion, which is different from corrosion in a submerged environment, and to resist the high work hardening pressures.
• Patent application EP 0 556 087 A1 generally describes an aqueous solution containing a water-soluble salt of an acid monocarboxylic containing an odd number of carbon; this solution is particularly suitable for inhibiting corrosion in a submerged environment, since this document mainly describes its use in water circulation refrigeration using antifreeze (see for example page 2, lines 52 to 54), where corrosion takes place in a submerged environment.
• the monocarboxylic acid is preferably heptanoic acid or undecanoic acid.
• Corrosion inhibitors commonly used hitherto in the field of wet work hardening are based on nitrites or organic products like 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 processing flocculation.
• inhibitors can have other disadvantages: poor odors, risks to public health (dermatoses, carcinogenic risks).
• the object of the invention is to provide an aqueous treatment solution steel plate hardening providing satisfactory protection against corrosion, including atmospheric corrosion, without danger particular and generating effluents that are easy and economical to treat.
• Satisfactory protection against corrosion means protection at least equivalent to that obtained with conventional art solutions previous, commonly used for this application.
• Economic effluents are understood to mean effluents which can be treated in a conventional manner, in particular according to a conventional method of treatment of rolling effluents, while respecting discharge standards admissible in force.
• the work hardening of the sheet is therefore also carried out in a humid environment and there are also problems of atmospheric corrosion, especially during storage of the tubes (in bundles), and in particular at points of contact of the tubes together in the same boot.
• the invention therefore aims to provide an aqueous treatment solution of steel plate hardening providing satisfactory protection against corrosion without giving a greasy appearance and making it possible to save degreasing operation, especially in case of coating or setting painting.
• an aqueous solution of salts heptanoic acid can also be used as a solution work hardening, because these salts resist high pressures hardening and also provide resistance to atmospheric corrosion.
• the sheet treated with this solution does not have a greasy appearance and it is often not even necessary to degrease it for operations for example coating or painting.
• Effluent treatment is further facilitated due to the character biodegradable from heptanoic acid salts.
• Another advantage of the invention is that these solutions do not have no risk to public health.
• the example which follows relates to the work hardening of sheets at the end of rolling.
• the hardening device is of a conventional type and comprises two superimposed work hardening cylinders and the strip's travel path sheet metal to be hardened is approximately horizontal and passes between the cylinders.
• the device At the level of the strip-cylinder grip, on the travel path, the device has spray nozzles for spraying homogeneous the upper and lower surfaces of a moving strip.
• These spray nozzles are connected by pumps to a solution tank aqueous work hardening treatment.
• the work hardening device also includes means for recovery of the treatment solution arranged under the path scrolling and connected to a wastewater treatment and purification station.
• an aqueous solution which, according to the invention, contains sodium heptanoate as salt water-soluble heptanoic acid and sodium perborate as an oxidant.
• the pH of the solution is adjusted to a value close to 9, for example by adding soda.
• 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 a tenth of that concentration.
• wet work hardening device we proceed in a conventional for continuous work hardening of a strip of sheet steel by spraying the lower and upper surfaces of the strip with the treatment solution according to the invention.
• the effluents solutions according to the invention are also easier to treat than prior art solutions based on nitrites.
• a wetting agent is added to the solution hardening.
• the wetting agent is of the nonionic type; her concentration is about 0.1%.
• a product can be used as a wetting agent.
• WITCO under the trade name PA 9017
• MAGNUSPRAY wetting agent from the family of polyethoxylated alcohols
• the function of the wetting agent is to spread the treatment solution of a homogeneously on the surface of the sheet to obtain a layer of protection and passivation of constant thickness.
• wetting agent in the work hardening solution according to the invention, allows to further lower the sufficient heptanoic acid salt and oxidant concentrations to obtain satisfactory resistance to corrosion, which makes it possible to treat effluent 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 planning then oil the sheet to protect it against corrosion in the longer term: in fact, this type of wetting agent does not disturb any spreading oil film.
• the work hardening solution according to the invention can be used in other plate hardening operations, in particular for the manufacture of tubes welded.
• the solution according to the invention has been used successfully for manufacturing tubes from sheet steel, especially "black” steel, crude steel from pickling or cold rolling or aluminized steel.
• the pH of the hardening solution can be adjusted depending on the type coating of steel.
• the tubes obtained have no appearance greasy and can be painted without previous degreasing.
• Tubes stored in bundles are very resistant to corrosion (even on the contact area between the tubes of the same boot).
• TOC total organic carbon
• WAC For effluent treatment efficiency tests, a salt is used aluminum called WAC 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 that is easily separated.
• This product is used in a conventional manner to treat effluents rolling facilities, facilities commonly found upstream hardening installations.
• the quality is therefore significantly improved (here by more than 40%). effluent treatability.
• the purpose of this example is to illustrate the protection performance against corrosion of treatment solutions according to the invention containing heptanoate sodium (designated as NaC7) and an oxidizing agent (sodium perborate - NaBO2, H2O2, 3H2O, designated by "Ox1").
• the molar concentration of oxidant must remain lower or equal to the molar concentration of corrosion inhibitor, here heptanoate sodium.
• a molar concentration of oxidizer of only about one tenth of that of the corrosion inhibitor may be sufficient.
• the purpose of this example is to illustrate the protection performance against corrosion of the work hardening treatment solutions according to the invention by compared to those of solutions of the prior art, in particular based on nitrites or organic products such as amine borates, under conditions approximating those of the targeted application.
• All the solutions according to the invention have a pH of approximately 9, obtained if necessary by adding sodium hydroxide.
• NaC7 denotes sodium heptanoate.
• 100 mm x 100 mm steel sheet samples are prepared, one series of work hardening treatment solutions to be tested and a series of solutions corrosive to sodium sulfate at different concentrations.
• Comparative series n ° 1 sodium nitrite.
• Corrosive Treatment solution sodium nitrite - g / 1 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 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 Na2S04 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, especially when adding a wetting agent to the solutions previously described sodium heptanoate and oxidant.
• the oxidant used here for the test is sodium nitrite, designated below. with "Ox2".
• wetting agent further reduces the concentrations of heptanoic acid salt and oxidant necessary for obtain both satisfactory corrosion protection and effluent easy and economical to process.
• Example 3 which concluded that sufficient concentration of the order of 0.05 mole / liter of acid salt heptanoic in a solution without wetting agent (but with oxidant), we could even achieve 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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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (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)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

Country Status (9)

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• 1995
  • 1995-12-07 FR FR9514440A patent/FR2742080B1/fr not_active Expired - Fee Related
• 1996
  • 1996-10-30 ES ES96402301T patent/ES2143162T3/es not_active Expired - Lifetime
  • 1996-10-30 EP EP96402301A patent/EP0778091B1/fr not_active Expired - Lifetime
  • 1996-10-30 DE DE69606270T patent/DE69606270T2/de not_active Expired - Fee Related
  • 1996-10-30 PT PT96402301T patent/PT778091E/pt unknown
  • 1996-10-30 AT AT96402301T patent/ATE188895T1/de not_active IP Right Cessation
  • 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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