Facility for production of high strength steel sheet or hot dip zinc coated high strength steel sheet excellent in elongation and hole expandability

摘要

Exemplary embodiments of a facility or an arrangement capable of producing a high strength steel sheet or a hot dip zinc coated high strength steel sheet according to the present invention are provided which can make a quenching facility and tempering facility continuous treatment facilities. For example, an improvement in the material quality can be effectuated due to tempering enable improvement of the hole expandability. In addition, an elongation of the sheet can be improved. For example, an exemplary production facility/arrangement for high strength steel sheet or hot dip zinc coated high strength steel sheet excellent in elongation and hole expandability can be provided by arranging in a continuous annealing facility or a continuous hot dip zinc coating facility or their joint facility or continuously with the same, (i) a quenching facility able to cool steel sheet after recrystallization or after recrystallization and after hot dip zinc coating down to a temperature region of the martensite transformation point or less, (ii) a tempering facility for tempering the steel sheet and holding its temperature, and (iii) a recooling facility for cooling the steel sheet to about 100° C. or less.