Method for producing plated steel sheet excellent in surface quality and press formability, and plated steel sheet produced by the method

Abstract

The present invention relates to a hot-dip galvanized steel sheet used for automobile outer panels, and more particularly, to a method for producing a hot-dip galvanized steel sheet excellent in surface quality and press formability.

Description

technical field [0001] The present invention relates to a plated steel sheet used for automobile outer panels, etc., and more particularly, to a method for producing a plated steel sheet excellent in surface quality and press formability, and a plated steel sheet produced by the method. Background technique [0002] Plated steel sheets coated with zinc, aluminum, etc. are widely used as steel sheets for automobile outer panels because they are excellent in corrosion resistance, weldability, and paintability. It needs to have a beautiful surface appearance, and also needs to have excellent formability during stamping. [0003] However, unlike an alloyed hot-dip galvanized steel sheet in which fine unevenness is formed on the surface during the alloying process, the coating layer of a coated steel sheet such as a hot-dip galvanized steel The surface after cladding is smooth, and the film itself is soft and has a low melting point, so it is easy to cause galling (galling) phen...

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Problems solved by technology

[0009] However, as shown in Patent Document 1, even if the average roughness (Ra) and the number of surface peaks (RPc) of the fine unevenness formed on the surface of the plated steel sheet are maintained at predetermined values, or as shown in Patent Document 2, even if the The sum of the volumes of the concave parts per unit area of ​​the galvanized steel sheet is adjusted to be more than the predetermined value, and the oil content and friction characteristics will still appear depending on the shape of the surface unevenness, so it will show a very different roughening phenomenon during stamping

[0010] That is, this is because, even if such as shot peening (Shot Blast), electrical discharge machining (Electro Discharge Texturing), laser processing (Laser Texturing), electron beam processing (Electro Beam Texturing) and TOPOCROM processing (TopoCrom Texturing), etc. The method of forming fine unevenness, or the sum of the surface roughness values ​​such as Ra and RPc of the indentation formed by projecting spherical solid particles directly onto the surface of the galvanized steel sheet and the volume of the concave part per unit area satisfy the proposed value, and it is only effective. The function of the suction port to absorb excess lubricating oil cannot play the role of lubricating to reduce the friction between the mold and the plated steel plate

[0011] Furthermore, in the case of Patent Document 3, in order to reduce the friction of the plated steel sheet and improve the press formability, it is not economical to additionally perform expensive lubrication treatment, and other weldability or adhesiveness is deteriorated, so it is not desirable. preferred

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