APPARATUS FOR PRODUCING HIGH STRENGTH STEEL SHEET OR HOT DIP ZINC PLATED HIGH STRENGTH STEEL SHEET EXCELLENT IN ELONGATION AND BORE EXPANDING CHARACTERISTICS

摘要

The present invention provides a facility able to produce high strength steel sheet or hot dip zinc coated high strength steel sheet which makes the quenching facility and tempering facility continuous treatment facilities so that not only does the improvement in the material quality due to tempering enable improvement of the hole expandability, but also the elongation can be improved, that is, a production facility for high strength steel sheet or hot dip zinc coated high strength steel sheet excellent in elongation and hole expandability characterized by arranging in a continuous annealing facility or a continuous hot dip zinc coating facility or their joint facility or continuously with the same 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, a tempering facility for tempering the steel sheet and holding its temperature, and a recooling facility for cooling the steel sheet to 100°C or less.