EP0492319B1 - Tôle traitée en surface pour boîtes soudées - Google Patents

Tôle traitée en surface pour boîtes soudées Download PDF

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Publication number
EP0492319B1
EP0492319B1 EP91121430A EP91121430A EP0492319B1 EP 0492319 B1 EP0492319 B1 EP 0492319B1 EP 91121430 A EP91121430 A EP 91121430A EP 91121430 A EP91121430 A EP 91121430A EP 0492319 B1 EP0492319 B1 EP 0492319B1
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EP
European Patent Office
Prior art keywords
chromium
metallic chromium
layer
granular
metallic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP91121430A
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German (de)
English (en)
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EP0492319A2 (fr
EP0492319A3 (en
Inventor
Hiroki Iwasa
Toyofumi Watanabe
Hirohide Furuya
Yoshitaka Kashiyama
Takashi Awaya
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JFE Engineering Corp
Original Assignee
NKK Corp
Nippon Kokan Ltd
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Publication date
Priority claimed from JP2413925A external-priority patent/JPH04224696A/ja
Priority claimed from JP2413931A external-priority patent/JPH04224697A/ja
Application filed by NKK Corp, Nippon Kokan Ltd filed Critical NKK Corp
Publication of EP0492319A2 publication Critical patent/EP0492319A2/fr
Publication of EP0492319A3 publication Critical patent/EP0492319A3/en
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Publication of EP0492319B1 publication Critical patent/EP0492319B1/fr
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/38—Chromatising
    • 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
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/24—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing hexavalent chromium compounds

Definitions

  • This invention relates to an eletrolytically chromated steel sheet and, more particularly, to a surface treated steel sheet which has a high degree of weldability and presents a surface having an outstanding good appearance when painted, and is, therefore, suitable for use in making cans by high-speed resistance seam welding.
  • An electrolytically chromated steel sheet which is obtained by forming on a surface of a steel sheet a film composed of an undercoating layer of metallic chromium and an overcoating hydrated chromium oxide layer consisting mainly of chromium oxide, is widely used for making cans, such as cans for beverage and food, pail cans , 18-liter cans and oil cans, since it is excellent in paintability and corrosion resistance, and is less expensive than a tin plate.
  • the film is usually composed of an undercoating layer of metallic chromium having a thickness of, say, 0.005 to 0.02 micron and an overcoating hydrated chromium oxide layer having a thickness of, say, 0.01 to 0.02 micron.
  • the one-step method forms the metallic chromium and hydrated chromium oxide layers simultaneously by the cathode electrolytic treatment of a steel sheet in an electrolyte consisting mainly of chromium trioxide and containing one or two additives selected from sulfates and fluorine compounds.
  • the two-step method repeats the one-step method to form the metallic chromium and hydrated chromium oxide layers, but further includes dissolving away the hydrated chromium oxide layer and forming a new hydrated chromium oxide layer by cathode electrolytic treatment in an electrolyte consisting mainly of chromic acid.
  • the electrolytically chromated steel sheet has hitherto been used for making a two-piece can, which is made by drawing, or a three-piece can, which is made by joining the seams with an adhesive, such as an organic resin or a special cement. It has, however, not often been used for making a seam welded can, since it is very low in weldability.
  • the electrolytically chromated steel sheet known in the art has a low weldability for the reasons which will hereunder be set forth.
  • the overcoating hydrated chromium oxide layer serving as a surface coating is of the nature not conducting electricity or heat. Therefore, the hydrated chromium oxide layer acts as an insulator and produces a very high contact (or static) resistance when electric resistance seam welding is carried out to form a welded seam extending longitudinally of the body of a can.
  • the value of contact resistance can be used as a measure for evaluation as to the possibility of a localized flow of an excessive current in a welding job. If a high value of contact resistance exists, a welding current is allowed to flow only through so narrow a path that a localized flow of an excessive current is likely to occur.
  • the electrolytically chromated steel sheet has a very high value of contact resistance as compared with any other type of surface treated steel sheet used for making welded cans. Therefore, the welding current flows only in a small quantity during the initial stage of a welding operation and begins to flow in the desired quantity only after the passage of a certain length of time. As a consequence, the localized heating of the steel sheet is likely to occur and result in a splashing, or the formation of a welded joint having blowholes or other defects.
  • this type of chromated steel sheet When this type of chromated steel sheet is used to make a welded can, however, it exhibits different heat- and cooling characteristics between the overlapping inner and outer edge portions thereof to be welded together to form a seam extending longitudinally of the body of a can. More specifically, it is usually the case that, as an inner electrode roll is smaller in diameter than an outer electrode roll, the inner edge portion of the sheet is likely to generate a greater amount of heat, and that the inner edge portion is also slower in cooling than the outer edge portion. Therefore, the inner edge portion is likely to cause a splash or flash of molten material from its edge, and a nugget is formed closer to the inner surface of the can than to its outer surface.
  • This method is based on the concept that, if the formation of granular metallic chromium is restrained on the other surface of the steel sheet, it is possible to attain a low contact resistance on the surface of the sheet defining the inner surface of a can relative to the surface defining the outer surface of the can to thereby equalize the amounts of heat generated in the inner and outer surfaces of the can being manufactured and prevent any splash on its inner surface.
  • an object of this invention to provide an electrolytically chromated steel sheet for a welded can which has an outstandingly good high-speed seam weldability without grinding and also can form a lacquered or printed surface having an outstandingly good outlook.
  • the structures of the films formed on both sides of the steel sheet as defined above not only enable the satisfactory passage of a welding current and the prevention of localized heating, as a result of the destruction of hydrated chromium oxide by granular metallic chromium on one side of the sheet, but also make it possible to:
  • the film on that side of the steel sheet which will form the outer surface of a can may not contain any granular metallic chromium, or that, if it contains any granular metallic chromium, it may contain only an extremely small proportion of relatively large particles.
  • the results of our study confirm that the electrolytically chromated steel sheet as hereinabove defined presents a lacquered or painted surface having an outstandingly good outlook, as well as it has an improved weldability.
  • an electrolytically chromated steel sheet carrying on one of the two principal surfaces thereof an electrolytic chromating film including a metallic chromium layer containing a high proportion of granular metallic chromium having a large particle diameter, while on the other of the two principal surfaces thereof, it carries an electrolytic chromating film including either a metallic chromium layer in a continuous sheet form which is free of any granular metallic chromium, or a metallic chromium layer containing only a very low proportion of granular metallic chromium having a large particle diameter.
  • This invention may be reduced to practice in a variety of modes as will hereunder be set forth:
  • the electrolytically chromated steel sheet of this invention is essentially characterized by carrying on one of the two principal surfaces thereof an electrolytic chromating film including a metallic chromium layer containing a high proportion of granular metallic chromium having a large particle diameter, while on the other of the two principal surfaces thereof, it carries an electrolytic chromating film including either a metallic chromium layer in sheet form which is free of any granular metallic chromium, or a metallic chromium layer containing only a very low proportion of granular metallic chromium having a large particle diameter.
  • a variety of methods can be employed to form a metallic chromium layer containing the desired granular metallic chromium on the sheet surface to be treated.
  • a few examples of the methods are:
  • the anode electrolytic treatment of the steel surface prior to electrolytic chromating is carried out in a bath which is usually employed in the cathode electrolytic treatment for metallic chromium plating or hydrated chromium oxide coating, whereby a very thin hydrated chromium oxide film having a coating weight not exceeding 2 mg/m2 is deposited on the electrolytically treated surface.
  • This film has a multiplicity of fine discontinuous portions which enable the subsequent electrolytic chromating treatment to form a metallic chromium layer consisting of granular metallic chromium on the steel surface. This method, therefore, makes it possible to form a film containing granular metallic chromium directly on the steel surface.
  • the other two methods i.e. anode electrolytic treatment during chromium plating and discontinuous electrolytic treatment, are also carried out in a bath which is usually employed in the cathode electrolytic treatment for chromium plating or hydrated chromium oxide coating, whereby a hydrated chromium oxide film which facilitates the formation of granular metallic chromium (i.e. which has a low anion content and a very small thickness) is formed on metallic chromium in sheet form adhering to the steel surface.
  • This film has fine discontinuous portions containing anions locally which enable the subsequent electrolytic chromating treatment to form granular metallic chromium on the whole surface of the metallic chromium in sheet form.
  • the metallic chromium layer which is formed on one of the steel surfaces and contains a high proportion of granular metallic chromium having a large particle diameter consists either of a mass of granular metallic chromium adhering to the steel surface, or of a combination of metallic chromium adhering in sheet form to the steel surface and granular metallic chromium formed thereon.
  • the layer having either of these two structures can be formed if an appropriately selected method is employed as hereinabove described.
  • the metallic chromium layer consists of a mass of granular metallic chromium, it is required to contain 30 to 150 mg of metallic chromium per square meter. If it contains only less than 30 mg of chromium per square meter, the incomplete growth of granular metallic chromium results in only an incomplete reduction of contact resistance between the sheet surface forming the inner surface of a can and the electrode, and also between the contacting surfaces of the sheet. The incomplete growth of chromium particles means also the incomplete coating of the steel surface and therefore the low corrosion resistance thereof. Any layer containing more than 150 mg of chromium per square meter is uneconomical, though it may satisfactorily achieve the intended result.
  • the particle diameter and density of granular metallic chromium have a critical bearing on the intended result. It is necessary to ensure that granular metallic chromium having a large particle diameter be formed in a high density, or proportion. More specifically, it is necessary to ensure that at least 30 particles having a diameter of at least 0.03 micron be formed in an area of square micron.
  • the metallic chromium layer consisting of a mass of granular metallic chromium usually contains several hundred particles per square micron of its surface. It is, however, relatively large particles that contribute to achieving a lower contact resistance upon application of pressure by the electrode. Hardly any such result can be expected from particles having a diameter which is smaller than 0.03 micron. Even sufficiently large particles fail to produce any satisfactory result, unless they are uniformly distributed. Therefore, it is necessary for the layer to have a density of at least 30 particles per square micron.
  • the metallic chromium layer consists of metallic chromium adhering in sheet form to the steel surface and granular metallic chromium formed thereon, it is required to contain 50 to 150 mg of metallic chromium per square meter. If it contains only less than 50 mg of chromium per square meter, the incomplete growth of granular metallic chromium results in only an incomplete reduction of contact resistance between the sheet surface forming the inner surface of a can and the electrode, and also between the contacting surfaces of the sheet, though it may he satisfactory in corrosion resistance. Any layer containing more than 150 mg of chromium per square meter is uneconomical, though it may satisfactorily achieve the intended result. Therefore 150 mg of chromium per square meter is set as an upper limit.
  • the metallic chromium layer of this construction is also required to contain a high density or proportion of granular metallic chromium having a large particle diameter. More specifically, it is required to contain 50 to 300 particles having a diameter of at least 0.03 micron per square micron. It is relatively large particles that contribute to achieving a lower contact resistance upon application of pressure by the electrode, and hardly any such result can be expected from particles having a diameter which is smaller than 0.03 micron, as hereinabove stated.
  • the deposition of granular metallic chromium on metallic chromium in sheet form tends to be affected to some extent by the crystal orientation of the underlying chromium.
  • granular metallic chromium is distributed less uniformly than in the metallic chromium layer consisting solely of granular chromium. Therefore, the layer is required to contain at least 50 sufficiently large particles per square micron to ensure that the granular chromium show the expected result. This is a proportion which is higher than the minimum proportion of such particles that the layer consisting solely of granular chromium is required to contain.
  • the maximum proportion of 300 particles per square micron is a limit set to save the amount of chromium, and does not mean that a higher proportion will adversely affect the result expected from granular chromium.
  • the steel surface which has been coated with granular metallic chromium is electrolytically chromated, whereby a hydrated chromium oxide layer is formed on the metallic chromium layer.
  • the hydrated chromium oxide layer is provided for ensuring the corrosion resistance and paintability of the steel surface.
  • the layer is required to contain 3 to 15 mg of metallic chromium per square meter. If it contains only less than 3 mg of chromium per square meter, the steel surface is undesirably low in corrosion resistance, and if it contains more than 15 mg of chromium per square meter, a satisfactorily low contact resistance is difficult to achieve between the steel surface forming the inner surface of a can and the electrode.
  • the metallic chromium layer which is formed on the other of the steel surfaces is a layer containing no granular chromium (i.e. consisting solely of chromium in sheet form), or a layer in which granular chromium having a large particle diameter occupies a by far lower proportion than in the layer on the one steel surface. If the proportion of such granular chromium on the other steel surface exceeds a certain limit, the contact resistance at the interface between the contacting portions of the steel sheet becomes too low, as compared with the contact resistance at the interface between the film and the electrode, to generate a sufficiently large amount of heat in those contacting portions.
  • the metallic chromium layer on the other steel surface in which granular chromium having a large particle diameter occupies a very low proportion may consist of either a mass of granular chromium adhering to the steel surface, or a combination of chromium adhering in sheet form to the steel surface and granular chromium formed on it, as is the case with the layer on the one steel surface. Either of these two layer structures can be formed by employing an appropriate method as hereinabove described.
  • a layer of the former construction is usually formed by the anode electrolytic treatment which is carried out in a plating bath prior to chromium plating, while a layer of the latter construction is usually formed by the fine anode electrolytic treatment which is carried out after chromium plating, or the discontinuous plating which is carried out by allowing a dipping time during chromium plating. If the fine anode electrolytic treatment is carried out on the other steel surface after chromium plating, however, no cathode electrolytic treatment is thereafter carried out, since the cathode electrolytic treatment forms too large an amount of granular chromium having a large particle diameter to be acceptable within the limits as defined by this invention.
  • the other steel surface is required to contain only a very low proportion of granular chromium having a large particle diameter, as hereinabove stated. More specifically, the granular chromium which is formed on the other steel surface is required to contain only less than 15 particles having a diameter of at least 0.03 micron per square micron of the layer, irrespective of the structure of the layer. It is relatively large particles having a diameter of at least 0.03 micron that contribute to achieving a lower contact resistance upon application of pressure by the electrode. If the layer contains 15 or more such particles per square micron, it begins to show a lower contact resistance, though locally, and disables the steel sheet to exhibit the intended result. Moreover, it will present only a printed or lacquered surface having an outlook which is dark and does not have a good color tone.
  • the Japanese patent application laid open under No. 35797/1988 discloses a method of producing an electrolytically chromated steel sheet carrying granular metallic chromium on one surface thereof, but hardly any such chromium on the other surface thereof by subjecting the one surface thereof at least once to anode electrolytic treatment during cathode electrolytic chromating treatment.
  • this method may hardly form any granular chromium on the other surface of the sheet, the amount of granular chromium which it forms on that surface is considerably greater than the maximum proportion defined for the sheet of this invention. More specifically, the granular chromium which is formed on the other surface of the sheet contains at least about 20 particles having a diameter of at least 0.03 micron per square micron. This is a proportion which is too high to be expected to produce the result of this invention.
  • the metallic chromium layer on the other surface of the sheet is defined as containing 30 to 150 mg of chromium per square meter, irrespective of its structure. If it contains only less than 30 mg of chromium per square meter, it fails to cover the sheet surface sufficiently to render it fully resistant to corrosion. Any layer containing more than 150 mg of chromium per square meter is uneconomical, though it may effectively achieve the intended result. Therefore 150 mg of chromium per square meter is set as an upper limit.
  • a hydrated chromium oxide layer is formed on the other surface of the sheet, too, when it is electrolytically chromated.
  • This layer ensures the corrosion resistance and paintability of the sheet, as hereinbefore stated.
  • the layer is required to contain 3 to 30 mg of chromium per square meter. If it contains only less than 3 mg of chromium per square meter, it fails to provide any satisfactory corrosion resistance and is also likely to give an undesirably low contact resistance. Any layer containing more than 30 mg of chromium per square meter is somewhat uneconomical, though it may not present any particular problem from a weldability standpoint. Moreover, the presence of too much hydrated chromium oxide is likely to give the sheet a colored surface having an uneven outlook due to the lack in uniformity of oxide distribution. Therefore 30 mg per square meter is set as an upper limit.
  • EXAMPLE 2 was repeated, except that cathodic on and off electrolysis was carried out at a cathode current density of 30 A/dm2.
  • EXAMPLE 1 was repeated, except that pretreatment was carried out on both surfaces under the conditions employed in EXAMPLE 1, except for the following:
  • EXAMPLE 9 was repeated, except that electrolytic chromating (cathodic on and off electrolysis) was carried out in a bath having a temperature of 45°C.
  • EXAMPLE 1 was repeated, except that cathodic on and off electrolysis was carried out by employing a cathode current density of 30 A/dm2 and repeating the on and off cycle twice.
  • EXAMPLE 2 was repeated, except that after the final chromating and before rinsing, posttreatment was carried out on both surfaces under the conditions employed in EXAMPLE 13.
  • EXAMPLE 15 was repeated, except that pretreatment was carried out at an anode current density of 5 A/dm2 by employing a solution containing 175 g of chromium trioxide, 5 g of Na2SiF6 and 0.9 g of Na2SO4 per liter and having a temperature of 40°C, and that electrolytic chromating was carried out by employing a solution having a temperature of 45°C.
  • EXAMPLE 17 was repeated, except that after the final chromating and before rinsing, posttreatment was carried out under the conditions listed below:
  • EXAMPLE 15 was repeated, except that electrolytic chromating was carried out in a solution having a temperature of 46°C.
  • EXAMPLE 17 was repeated, except that anodic electrolysis was carried out at an anode current density of 0.5 A/dm2.
  • EXAMPLE 15 was repeated, except that pretreatment was carried out by employing a solution containing 175 g of chromium trioxide, 5 g of Na2SiF6 and 0.9 g of Na2SO4 per liter and having a temperature of 40°C, and an anode current density of 5 A/dm2, while electrolytic chromating was carried out by using a solution temperature of 45°C and an electrolyzing time of 0.1 sec.
  • EXAMPLE 17 was repeated, except that cathodic electrolysis was carried out by employing a cathode current density of 150 A/dm2 and an electrolyzing time of 0.1 sec.
  • EXAMPLE 16 was repeated, except that after chromating and before rinsing, posttreatment was carried out on both surfaces under the conditions listed below:
  • EXAMPLE 17 was repeated, except that after the final chromating and before rinsing, posttreatment was carried out on both surfaces under the conditions listed below:
  • COMPARATIVE EXAMPLE 4 was repeated, except that intermediate anodic electrolysis was carried out on one surface alone by employing an anode current density of 0.2 A/dm2, and that the subsequent chromating was carried out on that surface alone.
  • COMPARATIVE EXAMPLE 4 was repeated, except that intermediate anodic electrolysis was carried out on one surface alone by employing an anode current density of 0.5 A/dm2.
  • COMPARATIVE EXAMPLE 4 was repeated, except that a cathode current density of 20 A/dm2 was employed instead of 40 A/dm2, and that intermediate anodic electrolysis and the subsequent cathodic electrolysis were carried out on one and the same surface alone.
  • COMPARATIVE EXAMPLE 9 was repeated, except that pretreatment was carried out on both surfaces by employing an anode current density of 10 A/dm2 for one surface and 2 A/dm2 for the other surface and an electrolyzing time of 0.3 sec. for each surface, and that for the electrolytic chromating cathodic electrolysis was carried out by employing a cathode current density of 40 A/dm2 and an electrolyzing time of 0.3 sec., and repeating the on and off cycle four times.
  • COMPARATIVE EXAMPLE 9 was repeated, except that for the electrolytic chromating cathodic electrolysis was carried out by emplying a cathode current density of 40 A/dm2 and an electrolyzing time of 0.3 sec., and repeating the on and off cycle four times, and that posttreatment was carried out on both surfaces under the conditions listed below:
  • COMPARATIVE EXAMPLE 4 was repeated, except that intermediate anodic electrolysis was carried out on one surface alone, and the subsequent chromating on that surface alone, too, and that posttreatment was carried out on both surfaces under the conditions listed below:
  • COMPARATIVE EXAMPLE 14 was repeated, except that an electrolyzing time of 0.5 sec. was employed for the posttreatment.
  • COMPARATIVE EXAMPLE 15 was repeated, except that an electrolyzing time of 0.5 sec. was employed for the posttreatment.
  • COMPARATIVE EXAMPLE 1 was repeated, except that pretreatment was carried out on one surface alone, and that chromating was carried out in a solution having a temperature of 50°C.
  • COMPARATIVE EXAMPLE 20 was repeated, except that electrolytic chromating was carried out by employing a cathode current density of 30 A/dm2 and an electrolyzing time of 0.3 sec.
  • COMPARATIVE EXAMPLE 19 was repeated, except that cathodic electrolysis was carried out by employing an electrolyzing time of 0.1 sec., and anodic electrolysis at an anode current density of 2 A/dm2.
  • COMPARATIVE EXAMPLE 20 was repeated, except that electrolytic chromating was carried out by employing a cathode current density of 160 A/dm2 and an electrolyzing time of 0.3 sec., and that posttreatment was thereafter carried out under the conditions shown below:
  • COMPARATIVE EXAMPLE 19 was repeated, except that anodic electrolysis was carried out at an anode current density of 2 A/dm2, and that after the final chromating and before rinsing, posttreatment was carried out on both surfaces under the conditions shown below:
  • COMPARATIVE EXAMPLE 23 was repeated, except that an electrolyzing time of 0.5 sec. was employed for the posttreatment.
  • COMPARATIVE EXAMPLE 24 was repeated, except that an electrolyzing time of 0.5 sec. was employed for the posttreatment.
  • the sheets were also evaluated for weldability, outlook after lacquering, and corrosion resistance (filiform corrosion resistance, corrosion resistance after lacquering, and corrosion resistance) by the methods as will hereinafter be described.
  • the results are shown in TABLES 6 to 10.
  • TABLES 6 to 10 confirm the presence of outstanding distinctions between the products of the EXAMPLES embodying this invention and those of the COMPARATIVE EXAMPLES in welding property and outlook after lacquering, and the great advantages of this invention.
  • the results of the evaluation confirm also the good corrosion resistance of all of the products embodying this invention.
  • Each sheet having the thickness of 0.22 mm was slit after printing, and the slit piece thereof was welded to make a size 202 can by a Soudronic wire mushroom welding machine employing a welding current set in a number of ways and in accordance with the conditions set forth below: Inverter power source frequency 500 Hz Welding rate 50 m/min. Electrode pressure 60 kgf Overlapping width 0.4 mm Nugget pitch 0.75 mm The range of a welding current within which a weld strength satisfying a tearing test could be obtained without causing any splashing was found from the graduations marked on a current setting device.
  • Each sheet having the thickness of 0.32 mm was slit after printing, and an attempt was made to weld the slit piece into a 5-gallon can by a Soudronic wire mushroom welding machine employing a welding current set in a number of ways and in accordance with the conditions set forth below: Inverter power source frequency 180 Hz Welding rate 22 m/min. Electrode pressure 65 kgf Overlapping width 0.8 mm Nugget pitch 1.2 mm The range of a welding current within which a weld strength satisfying a tearing test could be obtained without causing any splashing was found from the graduations marked on a current setting device. The meanings of the symbols are as defined above.
  • each welded can was coated with a layer of a transparent lacquer having a dry coating weight of 60 mg/m2, and was visually checked for any change in color tone.
  • the symbols used to express the results have the meanings as defined below: Symbol Meaning o Good. No change in color tone was found; x Bad. A change in color tone was found.
  • each welded can was printed with a wine-colored metallic paint, and the color tone of the printed surface was visually compared with that of the paint itself.
  • the symbols used to express the results have the meanings as defined below: Symbol Meaning o Good. No difference in color tone was found; x Bad. A difference in color tone was found.
  • each 5G welded can was visually inspected for any product of filiform corrosion that might have been formed in any defective portion of its coating during 12 months of its storage in a warehouse.
  • the symbols used to express the results have the meanings as defined below: Symbol Meaning o No product of filiform corrosion was found; x A product of filiform corrosion was found.
  • each sheet which would be used to form the inner surface of a welded can, was coated with a layer of an epoxy-phenol resin paint having a coating weight of 50 mg/m2, and after the paint had been baked, a cruciform cut was made in the coating layer by a sharp cutter knife so as to reach the steel surface, and a force was applied by an Erichsen tester to the other side of the sheet (used to form the outer surface of the can) to prepare an extruded test specimen having an extruded depth of 5 mm from the center of the cruciform cut.
  • the test specimen was dipped in an aqueous solution containing 1.5% of NaCl and 1.5% of citric acid and having a temperature of 38°C, and after 96 hours, measurement was made of the width of the corroded portion of the steel surface in the cruciform cut.
  • the symbols used to express the results have the meanings as defined below: Symbol Meaning o The corroded width was less than 1 mm; x The corroded width was 1 mm or more.
  • a stack of 100 sheets to be tested was placed between a pair of plates, and bound together tightly with steel wires passed around them in a cruciform way. After one month of storage in a place having a temperature of 25°C and a humidity of 85%, each sheet was examined for corrosion.
  • the symbols used to express the results have the meanings as defined below: Symbol Meaning o No corrosion was found; x Corrosion was found.

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Claims (6)

  1. Tôle d'acier traitée en surface pour une boîte soudée, portant sur l'une de ses deux surfaces principales un film de chromage électrolytique d'une teneur de 30 à 150 mg/m², réalisée en une couche de chrome métallique composée d'une masse de chrome métallique granulaire adhérant à ladite première surface, ledit chrome métallique granulaire contenant au moins 30 particules ayant un diamètre d'au moins 0,03 micron par micron carré de ladite couche et de 3 à 15 mg/m² (exprimé en terme de chrome métallique) d'une couche d'oxyde de chrome hydraté, formée sur ladite couche de chrome métallique, tandis que, sur l'autre desdites surfaces, ladite tôle porte un film de chromage électrolytique d'une teneur de 30 à 150 mg/m² d'une couche de chrome métallique composée de chrome métallique adhérant, sous forme de feuille à ladite autre surface et de chrome métallique granulaire appliqué sur ledit chrome, sous forme de feuille, ledit chrome métallique granulaire mentionné en dernier contenant moins de 15 particules d'un diamètre d'au moins 0,03 micron par micron carré de ladite couche de chrome métallique sur ladite autre surface et de 3 à 30 mg/m² (exprimé en terme de chrome métallique) d'une couche d'oxyde de chrome hydraté formée sur ladite couche de chrome métallique mentionnée en dernier.
  2. Tôle d'acier traitée en surface pour une boîte soudée, portant sur l'une de ses deux surfaces principales un film de chromage électrolytique comprenant de 50 à 150 mg/m², réalisée en une couche de chrome métallique composée d'une masse de chrome métallique granulaire adhérant à ladite première surface, et de chrome métallique granulaire, appliquée sur chrome se présentant sous forme de feuille, ledit chrome métallique granulaire contenant de 50 à 300 particules ayant un diamètre d'au moins 0,03 micron par micron carré de ladite couche et de 3 à 15 mg/m² (exprimé en terme de chrome métallique) d'une couche d'oxyde de chrome hydraté, formée sur ladite couche de chrome métallique, tandis que, sur l'autre desdites surfaces, ladite tôle porte un film de chromage électrolytique d'une teneur de 30 à 150 mg/m² d'une couche de chrome métallique composée de chrome métallique adhérant, sous forme de feuille, à ladite autre surface et de chrome métallique granulaire appliqué sur ledit chrome adhérant sur ladite autre surface, ledit chrome métallique granulaire mentionné en dernier contenant moins de 15 particules d'un diamètre d'au moins 0,03 micron par micron carré de ladite couche de chrome métallique sur ladite autre surface et de 3 à 30 mg/m² (exprimé en terme de chrome métallique) d'une couche d'oxyde de chrome hydraté formée sur ladite couche de chrome métallique mentionnée en dernier.
  3. Tôle d'acier traitée en surface pour une boîte soudée, portant sur l'une de ses deux surfaces principales un film de chromage électrolytique comprenant de 30 à 150 mg/m², réalisée en une couche de chrome métallique composée d'une masse de chrome métallique granulaire adhérant à ladite première surface, ledit chrome métallique granulaire contenant au moins 30 particules ayant un diamètre d'au moins 0,03 micron par micron carré de ladite couche et de 3 à 15 mg/m² (exprimé en terme de chrome métallique) d'une couche d'oxyde de chrome hydraté, formée sur ladite couche de chrome métallique, tandis que, sur l'autre desdites surfaces, ladite tôle porte un film de chromage électrolytique d'une teneur de 30 à 150 mg/m² d'une couche de chrome métallique composée de chrome métallique adhérant à ladite autre surface, ledit chrome métallique granulaire mentionné en dernier contenant moins de 15 particules d'un diamètre d'au moins 0,03 micron par micron carré de ladite couche de chrome métallique sur ladite autre surface et de 3 à 30 mg/m² (exprimé en terme de chrome métallique) d'une couche d'oxyde de chrome hydraté formée sur ladite couche de chrome métallique mentionnée en dernier.
  4. Tôle d'acier traitée en surface pour une boîte soudée, portant sur l'une de ses deux surfaces principales un film de chromage électrolytique comprenant de 50 à 150 mg/m², réalisée en une couche de chrome métallique composée d'une masse de chrome métallique granulaire adhérant sous forme de feuille à ladite première surface, et de chrome métallique granulaire, appliquée sur le chrome se présentant sous forme de feuille, ledit chrome métallique granulaire contenant de 50 à 300 particules ayant un diamètre d'au moins 0,03 micron par micron carré de ladite couche et de 3 à 15 mg/m² (exprimé en terme de chrome métallique) d'une couche d'oxyde de chrome hydraté formée sur ladite couche de chrome métallique tandis que, sur l'autre desdites surfaces ladite tôle porte un film de chromage électrolytique comprenant de 30 à 150 mg/m² d'une couche de chrome métallique composée d'une masse de chrome métallique granulaire adhérant à ladite autre surface, ledit chrome métallique granulaire mentionné en dernier comprenant moins de 15 particules d'un diamètre d'au moins 0,03 micron par micron carré de ladite couche de chrome métallique appliquée sur l'autre surface et de 3 à 30 mg/m² en terme de chrome métallique) d'une couche d'oxyde de chrome hydraté formée sur ladite couche de chrome métallique mentionnée en dernier.
  5. Une tôle d'acier traitée en surface pour une boîte soudée, portant sur l'une de ses deux surfaces principales un film de chromage électrolytique comprenant de 30 à 150 mg/m², d'une couche de chrome métallique composée d'une masse de chrome métallique granulaire adhérant à ladite première surface, ledit chrome granulaire comprenant au moins 30 particules d'un diamètre d'au moins 0,03 micron par micron carré de ladite couche, et de 3 à 15 mg/m² (en terme de chrome métallique) d'une couche d'oxyde de chrome hydraté formée sur ladite couche de chrome métallique, tandis que, sur l'autre desdites surfaces, ladite tôle porte un film de chromage électrolytique comprenant de 30 à 150 mg/m² d'une couche de chrome métallique composée de chrome métallique adhérant sous forme de feuille à ladite autre surface et de 3 à 30 mg/m² (en terme de chrome métallique) d'une couche d'oxyde de chrome hydraté formée de ladite couche de chrome métallique mentionnée en dernier.
  6. Tôle d'acier traitée en surface pour boîte soudée portant sur l'une de ses deux surfaces principales un film de chromage électrolytique comprenant de 50 à 150 mg/m², d'une couche de chrome métallique composée de chrome métallique adhérant sous forme de feuille à ladite première surface, et de chrome métallique granulaire appliqué sur ledit chrome, sous forme de feuille, ledit chrome granulaire comprenant de 50 à 300 particules ayant un diamètre d'au moins 0,03 micron par micron carré de ladite couche et de 3 à 15 mg/m² (exprimé en terme de chrome métallique) d'une couche d'oxyde de chrome hydraté formée sur ladite couche de chrome métallique, tandis que, sur l'autre desdites surfaces, ladite feuille porte un film de chromage électrolytique comprenant de 30 à 150 mg/m² de couche de chrome métallique composée de chrome métallique adhérant, sous forme de feuille à ladite autre surface et de 3 à 30 mg/m² (exprimé en terme de chrome métallique), d'une couche d'oxyde de chrome hydraté formée sur ladite couche de chrome métallique mentionnée en dernier.
EP91121430A 1990-12-26 1991-12-13 Tôle traitée en surface pour boîtes soudées Expired - Lifetime EP0492319B1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2413925A JPH04224696A (ja) 1990-12-26 1990-12-26 溶接缶用表面処理鋼板
JP413925/90 1990-12-26
JP2413931A JPH04224697A (ja) 1990-12-26 1990-12-26 溶接缶用表面処理鋼板
JP413931/90 1990-12-26

Publications (3)

Publication Number Publication Date
EP0492319A2 EP0492319A2 (fr) 1992-07-01
EP0492319A3 EP0492319A3 (en) 1993-02-24
EP0492319B1 true EP0492319B1 (fr) 1995-03-08

Family

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Application Number Title Priority Date Filing Date
EP91121430A Expired - Lifetime EP0492319B1 (fr) 1990-12-26 1991-12-13 Tôle traitée en surface pour boîtes soudées

Country Status (8)

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EP (1) EP0492319B1 (fr)
KR (1) KR960012183B1 (fr)
AU (1) AU656929B2 (fr)
BR (1) BR9105569A (fr)
CA (1) CA2058149A1 (fr)
DE (1) DE69107978T2 (fr)
MX (1) MX9102635A (fr)
MY (1) MY111396A (fr)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2016366068B2 (en) * 2015-12-11 2020-02-13 Jfe Steel Corporation Steel sheet for cans and production method for steel sheet for cans
JP7218201B2 (ja) * 2019-02-13 2023-02-06 アルバックテクノ株式会社 アルミニウム製部品の酸化皮膜の再生方法

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0194654B1 (fr) * 1985-03-15 1991-07-31 Kawasaki Steel Corporation Rubans d'acier sans étain utilisables pour la fabrication de boîtes soudées et procédé de production
JPH0637713B2 (ja) * 1988-02-27 1994-05-18 日本鋼管株式会社 電解クロメート処理鋼板の製造方法
JP2576570B2 (ja) * 1988-02-27 1997-01-29 日本鋼管株式会社 電解クロメート処理鋼板の前処理方法
US4898648A (en) * 1988-11-15 1990-02-06 Pacific Bell Method for providing a strengthened conductive circuit pattern

Also Published As

Publication number Publication date
EP0492319A2 (fr) 1992-07-01
BR9105569A (pt) 1992-09-01
AU656929B2 (en) 1995-02-23
EP0492319A3 (en) 1993-02-24
AU8889091A (en) 1992-07-02
KR920012520A (ko) 1992-07-27
MX9102635A (es) 1992-06-01
CA2058149A1 (fr) 1992-06-27
MY111396A (en) 2000-04-29
DE69107978D1 (de) 1995-04-13
KR960012183B1 (ko) 1996-09-16
DE69107978T2 (de) 1995-10-26

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