Steel sheet for fuel tanks and process for manufaturing the sheet
A manufacturing method, technology of fuel tanks, applied in the direction of metal material coating process, coating, plating of superimposed layers, etc., can solve the problems of different color tone parts, poor surface appearance, etc.
Active Publication Date: 2010-11-03
JFE STEEL CORP
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Problems solved by technology
[0008] However, it has been found that the steel sheet for fuel tanks has the following problems: the surface of the chromate coating shows interference color, and depending on the situation, the color tone of the inside of the steel sheet surface is partially different, and the surface appearance is poor.
Method used
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Embodiment 1
[0090] Contains C: 0.0015%, Si: 0.01%, Mn: 0.08%, P: 0.011%, S: 0.008%, Al: 0.05%, N: 0.0019%, Ti: 0.035%, Nb: 0.003% by mass % And B: 0.004%, and the balance is composed of Fe and unavoidable impurities, and the electroplated Zn-Ni alloy steel sheet (Ni: 12% by mass, adhesion amount per surface: 20g / m 2 ).
[0091] At this time, Zn-Ni alloy plating layers with average crystal grain sizes of 1.0 μm and 0.3 μm on the plating surface were formed by changing the plating line speed to two standards of 90 mpm and 160 mpm and changing the current density. The photographs of the coating surface with average grain size of 1.0 μm and 0.3 μm are shown in figure 1 with figure 2 . In addition, the average crystal grain size was obtained as a circle-equivalent grain size by observing a scanning electron micrograph at a magnification of 3,000 to 20,000 and counting the number of crystals per unit area.
[0092] Then, as a surface conditioning treatment, the acidic plating solution was ...
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Abstract
A steel sheet for fuel tanks which has a Zn-Ni alloy coating electroplated on at least one side of the sheet and a chromate coating formed on the alloy coating. The chromate coating exhibits a change in the build-up of chromium after immersion in boiling water for 30 minutes of within 2% based on the build-up of chromium before the immersion, an L value (indicating the surface color tone of steel sheet) of 55 or above, and a difference between the maximum and minimum L values of within 3. The chromate coating can be formed by applying a chromate treatment fluid which contains chromic acid at a trivalent chromium / total chromium mass ratio exceeding 0.5, phosphoric acid at a phosphoric acid / total chromium mass ratio of 0.1 to 5.0 and an organic reducing agent onto the above alloy coating and heating the resulting sheet. The steel sheet exerts excellent corrosion resistance against fuels such as gasoline, alcohols, and alcohol blended gasolines over a long period and is excellent in surface appearance.
Description
technical field [0001] The present invention mainly relates to steel sheets for fuel tanks, especially steel sheets for fuel tanks used in environments containing organic acids highly corrosive to metals, such as when gasoline contains a small amount of water or formic acid is generated due to gasoline deterioration, and its manufacture method. Background technique [0002] Conventionally, the materials for gasoline tanks of automobiles, motorcycles, etc., for example, mainly use the following steel plates: the tin (Sn)-lead (Sn)-lead ( Pb) alloy steel plate; or a multi-coated steel plate in which Sn-Pb alloy is hot-plated on the nickel (Ni) electroplating layer. [0003] However, although the Sn-Pb alloy-coated steel sheet is excellent in workability and chemical resistance to gasoline and the like, the coating is soft and easily damaged, and electrochemically inactive (expensive) compared with iron (Fe), so There is no sacrificial anode protection for Fe. Therefore, whe...
Claims
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Patent Timeline
Login to View More IPC IPC(8): C23C28/00C23C22/30C23C22/33
CPCC23C28/3455C25D7/0614C23C28/345C23C28/00C23C28/321C23C22/33C25D5/48C25D3/565
Inventor 樱井理孝马场伸壮多田千代子名越正泰谷本亘
Owner JFE STEEL CORP