Hot-rolled galvanized steel sheet having excellent galling resistance, formability and sealer-adhesion property and method for manufacturing same
AssigneePosco
InventorsSang-Heon KIM, Hyeon-Seok HWANG, Suk-Kyu LEE, Sun-Ho JEON, Yon-Kyun SONG, Bong-Hwan YOO
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Abstract
Disclosed are a hot-rolled galvanized steel sheet having excellent galling resistance and formability, and a method for manufacturing the same. The hot-rolled galvanized steel sheet, includes: a base steel; and a hot-rolled galvanizing layer formed on the surface of the base steel, wherein the hot-rolled galvanizing layer provides a hot-rolled galvanized steel sheet having a Mn crystallite having a size of 10 μm or less between the resin dendrites of zinc that form sequins.
Claims20
A hot-rolled galvanized steel sheet comprising:
- a base steel;
- and
- a hot-rolled galvanizing layer disposed on a surface of the base steel,
- wherein the hot-rolled galvanizing layer contains 0.1 to 0.8 weight percentage (wt %) of aluminum (Al), 0.05 to 1 wt % of manganese (Mn), with a remainder of zinc (Zn) and inevitable impurities, and
- a surface of the hot-rolled galvanizing layer is provided with a crystallite having a major axis length of 1 to 20 micrometers (μm).
A method for manufacturing a hot-rolled galvanized steel sheet, the method comprising:
- a plating layer forming step of depositing a steel sheet in a hot-rolled galvanizing solution, containing 0.1 to 0.8 weight percentage (wt %) of aluminum (Al), 0.05 to 1 wt % of manganese (Mn), with a remainder of zinc (Zn) and inevitable impurities, and taking out the deposited steel sheet therefrom to form a plating layer that forms a hot-rolled galvanizing layer;
- a primary cooling step of cooling the steel sheet, on which the hot-rolled galvanizing layer is formed, at a cooling rate of −10 degrees Celsius per second (° C./s) until a temperature of the steel sheet reaches 420° C.;
- a secondary cooling step of cooling the steel sheet at a cooling rate of −8° C./s until the temperature of the steel sheet reaches 418° C. from 420° C.;
- and
- a tertiary cooling step of cooling the steel sheet at a steel sheet temperature of 418° C. or less at a cooling rate of −10° C./s or more to form the hot-rolled galvanizing layer.
Dependencies are inferred from the claim text.