Method of producing hot-dip aluminum-based alloy-coated steel sheet

Abstract

Provided is (i) a hot-dip Al-based alloy-coated steel sheet which includes a coated layer having a surface on which fine spangles are stably and sufficiently formed and which has a beautiful surface appearance due to the fine spangles thus formed on the surface of the coated layer, and (ii) a method of producing such a hot-dip Al-based alloy-coated steel sheet. The hot-dip Al-based alloy-coated steel sheet includes: a substrate steel sheet; and a hot-dip aluminum-based alloy coated layer which is formed on a surface of the substrate steel sheet and which contains boron at an average concentration of not less than 0.005 mass % and contains potassium at an average concentration of not less than 0.0004 mass %.

1 - 3 . (canceled) 
     
     
         4 . A method of producing a hot-dip aluminum-based alloy-coated steel sheet, comprising:
 a coating step of dipping a substrate steel sheet in a hot-dip aluminum-based alloy-coating bath which contains aluminum as a main component,   the hot-dip aluminum-based alloy-coating bath containing boron at a concentration of not less than 0.005 mass % and not more than 3.0 mass % and containing potassium at a concentration of not less than 0.0004 mass % and not more than 0.02 mass %.   
     
     
         5 . The method as set forth in  claim 4 , wherein the hot-dip aluminum-based alloy-coating bath contains boron at a concentration of not less than 0.02 mass % and not more than 3.0 mass % and contains potassium at a concentration of not less than 0.0008 mass % and not more than 0.02 mass %. 
     
     
         6 . The method as set forth in  claim 4 , further comprising:
 a composition adjusting step of adjusting a composition of the hot-dip aluminum-based alloy-coating bath,   the composition adjusting step including adding an aluminum master alloy containing boron and potassium.   
     
     
         7 . The method as set forth in  claim 5 , further comprising:
 a composition adjusting step of adjusting a composition of the hot-dip aluminum-based alloy-coating bath,   the composition adjusting step including adding an aluminum master alloy containing boron and potassium.