Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/10—Electroplating with more than one layer of the same or of different metals
  • C25D5/12—Electroplating with more than one layer of the same or of different metals at least one layer being of nickel or chromium
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/48—After-treatment of electroplated surfaces
  • C25D5/50—After-treatment of electroplated surfaces by heat-treatment
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/922—Static electricity metal bleed-off metallic stock
  • Y10S428/9335—Product by special process
  • Y10S428/941—Solid state alloying, e.g. diffusion, to disappearance of an original layer
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12458—All metal or with adjacent metals having composition, density, or hardness gradient
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12861—Group VIII or IB metal-base component
  • Y10T428/12937—Co- or Ni-base component next to Fe-base component

Definitions

• the invention relates to a cold strip with an electrolytically applied nickel coating.
• Cold strips of this type are used in a wide variety of fields of application where modern manufacturing processes place high demands on the material in terms of mechanical properties, surface, processability and the like, which can only be met by cold-rolled products.
• Cold strip according to DIN 1624 has smooth, dense and glossy or evenly slightly roughened surfaces after cold forming by means of the correspondingly prepared rollers.
• Cold rolled strip is free of pores and cracks in the surface types RP and RPG, so that it can be surface-finished, in particular wrapped, without problems.
• a deep-drawn cold strip with an electrolytically applied nickel coating is therefore known
• thinner galvanic coatings are generally used in the field of coil plating than is usual for piece plating.
• suitable measures such as shielding the anode, flooding, inserting perforated plates in front of the anodes, it can be achieved that the deposits are made in a uniform layer thickness and differences in layer thickness are reduced to a minimum.
• the thinner layers have a lower corrosion resistance than thicker galvanic layers.
• the cold-rolled strip or cold-rolled and galvanized strips has a "tendency to stick" when annealed in the closed coil.
• glue points are preferably created during the cold rolling of low-carbon cold rolled strip, the surface of which has a minimal micro-roughness.
• glue points are formed sporadically or over a large area and continuously, where the surfaces lying on one another stubbornly and difficult to separate stick to each other.
• uncoiling is unwound, the adhesive points are separated / torn open, as a result of which the high-quality surface is damaged or destroyed.
• the gluing points can cause considerable operational disruptions.
• the invention is based on the task of avoiding the above-mentioned disadvantages of developing a galvanized cold strip and a method for its production which has no tendency to stick, is easy to form, has high diffusion depths of the coating and has favorable corrosion behavior, is improved in its electrochemical behavior and is economically producible.
• the nickel layer has a thickness of 1 to 6 microns and carries an electrolytically applied cobalt layer of a thickness of 0.01 to 1.0 microns
• the cold strip after coating with a temperature between 580 ° C. and 710 ° C is heat treated.
• Such a cold-coated and heat-treated cold strip surprisingly no longer tends to stick and shows a considerably more favorable corrosion behavior than the only nickel-coated strips which have the same total layer thickness.
• the electrochemical behavior of the cold strip according to the invention has values which are much more favorable than the only nickel-coated strips.
• Nickel coating, cobalt coating and heat treatment complement each other in a combinatorial manner to achieve an overall effect that goes beyond the sum effect, since a composite material is created which can be economically achieved with high-quality properties.
• Thermal treatment results in a significantly higher diffusion rate, which means that the quality of the formability of the composite system is improved and the penetration of the coating metals into the base material by diffusion shows a depth that is several times the coating thickness (including the nickel layer).
• the extremely thin cobalt coating a high technical and economic overall success is achieved.
• the base material is a low-carbon steel strip which has a nickel layer of 1.5 to 5 ⁇ m in thickness and a cobalt layer of 0.1 to 0.5 ⁇ m in thickness, the final heat treatment being carried out at a temperature between 600 ° C. and depending on the steel grade is 710 ° C.
• the thickness of the applied nickel layer is preferably 2 ⁇ m and the thickness of the applied cobalt layer is 0.1 ⁇ m.
• the base material of the cold strip is expediently characterized by a ferritic structure with embedded cementite with average grain sizes between 17.0 and 12.0 ⁇ m, the steel being 0.001 to 0.070% C, 0.170 to 0.350% Mn, 0.005 to 0.020% P, 0.005 to 0.020% S, 0.030 to 0.060% Al, 0.0015 to 0.0070% N, 0.003 to 0.006% B or instead of boron or additionally 0.005 to 0.15% Ti, the rest contains iron with the usual impurities. (All data in% by weight).
• the base metal preferably has a steel analysis Rest of iron with the usual accompanying elements. After deep drawing, smooth surfaces are achieved due to the very fine grain diameter.
• the composition of the steel is particularly important in order to achieve the globular shape of the grain and the grain size specified above over the entire ring length in the cold strip, even in the start and end areas.
• the process according to the invention for producing the cold strip described above is characterized in that a hot strip with a thickness of 1.8 to 2.8 mm is used as the starting material, the hot strip is cold rolled with or without intermediate annealing with such coordinated rolling degrees that a relative tip height of a maximum of 3% at a final thickness after cold rolling between 0.10 and 0.70 mm is achieved that the cold strip is then electrolytically in an alkaline degreasing bath at a temperature of 50 to 70 ° C, a current density of 5 to 60 A / dm 2 , Degreased for 5 to 30 seconds with or without polarity reversal, that after a rinsing process in 50 to 20% by weight of sulfuric acid is removed for 3 to 8 seconds, then electrolytically at a temperature of 50 to 80 ° C., at a current density nickel is from 5 to 70 ALDM 2 and at a pH value of 3.5 to 3.8, that after a rinsing operation a cobalt thereon electrodeposited layer at
• the cold strip obtained in this way has no tendency to stick, is distinguished by a current flow which is perceptible by chronoamperometric measurements and is of a considerably higher magnitude than is known, and is extremely economical due to the thin coating with expensive cobalt.
• nickel and cobalt penetrate deeply into the base material through diffusion.
• Texture Ferritic structure with embedded cementite.
• the grain size is: 17.0-12.0 ⁇ m (expressed as the mean grain size), in the present case as globular grains, in order to achieve smooth surfaces after deep-drawing due to the very fine grain diameter.
• composition of the steel is of crucial importance in order to achieve this shape and size over the entire length of the ring, also in the start and end areas.
• the production of the refined steel strips according to the invention is based on 1.8-2.8 mm thick hot strip.
• the hot strip is cold rolled with or without intermediate annealing, with coordinated rolling degrees, to a relative tip height of max. To reach 3%.
• the final thickness after cold rolling is 0.10-0.70 mm.
• the refined material is annealed with a defined protective gas (with approx. Up to 100% H 2 ) in order to achieve a stain-free surface.
• a defined protective gas with approx. Up to 100% H 2
• the temperature is 580-710 ° C depending on the steel type and applied galvanic layer thickness.
• the measurement is carried out after preactivation, which removes the natural oxide layer from the surface immediately before the chronoamperometric measurement.
• the pre-activation voltage applied was approximately -550 mV.
• the current transfer for the working electrodes constructed according to the invention was 80-80 mA. Due to the rapid formation of oxide, the current decreased very quickly and tends to asymtotically after 3 minutes to 0 mA. With the only nickel-plated working electrodes, the near O value (current) was only reached after 15-20 minutes.
• the electrode potential of the cold strip produced in accordance with the invention in alkaline electrolyte remains constant at least twice as long as the electrode consisting only of nickel-plated cold strip.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Thermal Sciences (AREA)
• Physics & Mathematics (AREA)
• Crystallography & Structural Chemistry (AREA)
• Mechanical Engineering (AREA)
• Electroplating Methods And Accessories (AREA)
• Manufacturing Of Steel Electrode Plates (AREA)
• Non-Insulated Conductors (AREA)
• Heat Treatment Of Sheet Steel (AREA)
• Electroplating And Plating Baths Therefor (AREA)
• Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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• 1987
  • 1987-08-10 DE DE19873726518 patent/DE3726518A1/de active Granted
• 1988
  • 1988-05-12 US US07/193,366 patent/US4910096A/en not_active Expired - Lifetime
  • 1988-06-28 EP EP88110266A patent/EP0303035B1/de not_active Expired - Lifetime
  • 1988-06-28 ES ES198888110266T patent/ES2026227T3/es not_active Expired - Lifetime
  • 1988-06-28 DE DE8888110266T patent/DE3864629D1/de not_active Expired - Lifetime
  • 1988-06-28 AT AT88110266T patent/ATE66865T1/de not_active IP Right Cessation
  • 1988-07-29 JP JP63188550A patent/JPH01111895A/ja active Granted
  • 1988-08-05 MX MX012576A patent/MX169599B/es unknown
  • 1988-08-08 DD DD88318779A patent/DD272880A5/de unknown
  • 1988-08-09 CA CA000574171A patent/CA1322345C/en not_active Expired - Fee Related
  • 1988-08-09 BR BR8803944A patent/BR8803944A/pt not_active Application Discontinuation
  • 1988-08-10 KR KR1019880010238A patent/KR960004786B1/ko not_active Expired - Fee Related
• 1991
  • 1991-10-03 GR GR91401482T patent/GR3002845T3/el unknown

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