| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a Si-containing high strength hot dip galvanized steel sheet having excellent surface properties by making Si oxide harmless, which inhibits reaction of the steel sheet and zinc during hot-dip galvanizing. <P>SOLUTION: A steel sheet containing at least 0.2-2.0% of Si, 0.2-3.0% of Mn, and 0.001-1.5% of Al so that the ratios of Si, Mn and Al satisfy formulas (1) to (3) is continuously subjected to a hot dip galvanizing treatment in a hot dip galvanizing line having a reducing furnace, wherein the logarithm ratio of steam partial pressure to hydrogen partial pressure in the atmospheric gas in a heating furnace or a heat keeping furnace satisfies formula (4): (1) 28≤(Si/(Si+Mn+Al))×100≤54; (2) 30≤(Mn/(Si+Mn+Al))×100≤70; (3) 0≤(Al/(Si+Mn+Al))×100≤30; and (4) -1.39≤log(P<SB POS="POST">H2O</SB>/P<SB POS="POST">H2</SB>)≤-0.695. <P>COPYRIGHT: (C)2012,JPO&INPIT |
