| 摘要 |
PROBLEM TO BE SOLVED: To prevent the generation of nonplating in a steel sheet contg. a prescribed amt. of reinforcing elements in particular by prescribing the coiling temp. SOLUTION: In this producing method, coiling after hot rolling is executed under the following temp. conditions: the coiling temp. is regulated to 780×[(Si(%)+Mn(%)/10+Cr(%)/10)<0.148> ( deg.C) or above. In this way, the surface layer part of the hot rolled steel sheet is internally oxidized by oxygen dissociated from black coating essentially consisting of iron oxide and covering the hot rolled steel sheet, and as a result, the concentration of the surface is suppressed to prevent the formation of the oxides of Si, Mn and Cr as reinforcing elements on the surface of the steel sheet. Thus, its wettability with hot dip zinc does not deteriorate. Thus, the production of the galvanized steel sheet free from the generation of nonplating and excellent in press workability and plating adhesion is made possible even in the case of a steel sheet contg. Si, Mn and Cr by >=0.7wt.% in total particularly.
|
