Method of Production of Hot Dipped Hot Rolled Steel Strip

Abstract

Production of hot dipped hot rolled steel strip by producing steel strip by casting by a thin slab continuous casting process and hot rolling, said steel strip containing, by mass %, C: 0.03% or more, Si: 0.02% or more, Mn: 0.15% or more, and Ca: 0.001% or more by heating it to a peak maximum steel strip temperature of 550° C. to less than 650° C. by a temperature elevation rate of 25° C./sec or more for 15 sec or more for oxidation, heating it to a peak maximum steel strip temperature of 700° C. to 760° C. so that the time when the steel strip temperature is 570° C. or more is 25 sec to 45 sec for reduction, then hot dipping it.

1 . A method of production of hot dipped hot rolled steel strip characterized by
 producing steel strip by casting by a thin slab continuous casting process and hot rolling, said steel strip containing, by mass %, C: 0.03% or more, Si: 0.02% or more, Mn: 0.15% or more, and Ca: 0.001% or more,   heating it to a peak maximum steel strip temperature of 550° C. to less than 650° C. by a temperature elevation rate of 25° C./sec or more for 15 sec or more for oxidation,   heating it to a peak maximum steel strip temperature of 700° C. to 760° C. so that the time when the steel strip temperature is 570° C. or more is 25 sec to 45 sec for reduction,   then hot dipping it.   
     
     
         2 . A method of production of hot dipped hot rolled steel strip as set forth in  claim 1  characterized in that said hot dipping is hot dip galvanization. 
     
     
         3 . A facility for production of hot dipped hot rolled steel strip which hot dips steel strip produced by casting and by the thin slab continuous casting process and by hot rolling,
 which facility for production of hot dipped hot rolled steel strip is characterized   by having a furnace used for oxidation and a furnace used for reduction and   by a ratio of length between said furnace used for oxidation and said furnace used for reduction along a conveyance direction of said steel strip being 0.5 to 0.9.   
     
     
         4 . A facility for production of hot dipped hot rolled steel strip as set forth in  claim 3 , characterized in that said steel strip passes through said furnace used for oxidation in a time of 15 sec to 25 sec.