Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Patent
1993-07-22
1995-02-28
Nakarani, D. S.
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
428328, 428331, 428336, 428341, 4284258, 428469, B32B 1508
Patent
active
053936051
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a zinciferous plated steel sheet excellent in press-formability and corrosion resistance.
BACKGROUND OF THE INVENTION
A zinciferous plated steel sheet having a zinciferous plating layer comprising zinc or a zinc alloy formed on at least one surface of the steel sheet is widely employed in various sectors of industry because of the excellent corrosion resistance. When using such a zinciferous plated steel sheet as a material for a business machine such as a copying machine, an audio equipment, a home electrical appliance or an automobile body, a press forming is applied to the zinciferous plated steel sheet. When using the zinciferous plated steel sheet as a material for a motor cover or a cartridge-type tank, a drawing forming is applied to the zinciferous plated steel sheet.
As compared with a cold-rolled steel sheet, however, the zinciferous plated steel sheet has a problem of a lower press-formability. More particularly, frictional resistance of the zinciferous plated steel sheet against a forming die during the press forming is larger than frictional resistance of the cold-rolled steel sheet against the forming die. The zinciferous plated steel sheet has therefore a poor lubricity. As a result, a severe press forming, if applied to the zinciferous plated steel sheet, causes a peeloff or a galling in the zinciferous plating layer.
Demand is recently increasing for a zinciferous plated steel sheet, which has a chromate film formed on the zinciferous plating layer by applying a chromating treatment to the zinciferous plated steel sheet and has a more excellent corrosion resistance. The zinciferous plated steel sheet having the chromate film formed on the zinciferous plating layer is excellent in corrosion resistance in the form of a flat sheet, i.e., corrosion resistance before a press forming. However, when applying a press forming to the zinciferous plated steel sheet having a chromate film, the poor press-formability as described above causes a peeloff of the chromate film or a blackish discoloration of the surface of the chromate film. Corrosion resistance and external appearance of the press-formed zinciferous plated steel sheet are thus deteriorated.
As a means to solve the above-mentioned problems, the conventional practice has been to improve lubricity of the zinciferous plated steel sheet by applying a lubricant oil onto the surface thereof prior to press-forming the zinciferous plated steel sheet.
However, application of the above-mentioned lubricant oil onto the surface of the zinciferous plated steel sheet has the following problems: manufacturing process; environment; and during the press forming even after applying the lubricant oil, thus causing deterioration of corrosion resistance of the press-formed zinciferous plated steel sheet.
As a zinciferous plated steel sheet which solves the above-mentioned problems and is excellent in press-formability and corrosion resistance even without applying a lubricant oil onto the surface thereof, the following zinciferous plated steel sheets are proposed: resistance, disclosed in Japanese Patent Provisional Publication No. 61-60,886 published on Mar. 28, 1986, which comprises: a steel sheet; a zinciferous plating layer formed on at least one surface of said steel sheet; a chromate film formed on said zinciferous plating layer, said chromate film having a weight within a range of from 5 to 200 mg/m.sup.2 per surface of said steel sheet; and a composite silicate film formed on said chromate film, which contains a water-dispersing internal lubricant and comprises a water-soluble or water-dispersing organic resin and a water-dispersing silica, said composite silicate film having a thickness within a range of from 0.3 to 3.0 .mu.m (hereinafter referred to as the "prior art 1"). lubricity, disclosed in Japanese Patent Provisional Publication No. 62-289,275 published on Dec. 16, 1987, which comprises: a steel sheet; a zinciferous plating layer formed on at least one surface of said steel sheet; and a
Kosaka Norio
Miyoshi Tatsuya
Okuma Toshiyuki
Watanabe Toyofumi
Yamashita Masaaki
Nakarani D. S.
NKK Corporation
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