Control and application of cooling path after rolling for hot strip based on ultra fast cooling

YUAN Guo(袁国), LI Zhen-lei(李振垒), LI Hai-jun(李海军), WANG Zhao-dong(王昭东), WANG Guo-dong(王国栋)

(State Key Laboratory of Rolling and Automation (Northeastern University), Shenyang 110819, China)

Abstract:Hot rolled strip requires diverse and flexible control of cooling path in order to take full advantages of strengthening mechanisms such as fine grain strengthening, precipitation strengthening, and transformation strengthening, adapting to the development of advanced steel materials and the requirement of reduction-manufacturing. Ultra fast cooling can achieve a great range of cooling rate, which provides the means that the hardened austenite obtained in high temperature region can keep at different dynamic transformation temperatures. Meanwhile, through the rational allocation of the UFC (ultra fast cooling) and LFC (laminar flow cooling), more flexible cooling path control and cooling strategy of hot rolled strip are obtained. Temperature distribution and control strategies under different cooling paths based on UFC are investigated. The process control temperature can be limited within 18 °C, and the mechanical properties of the steels get a great leap forward due to the cooling paths and strategies, which can decrease costs and create great economic benefits for the iron and steel enterprises.

Key words:hot rolled strip; ultra fast cooling; temperature field distribution; cooling path; cooling strategy