Keywords: existing rolling equipment, heat treatment, grain ultrafine,

　　At this stage, based on the existing rolling equipment, the technology of grain ultrafine is developed, and at the same time, a breakthrough in the existing mill capacity constraints, the pursuit of a 1 of ultra-fine grain size processing heat treatment technology research. It can be said that the two Japanese national projects started in 1997, "Super Metal Research Project" and "STX21: Super Steel Research Project", have accelerated the research on grain ultrafine. It puts forward the future research orientation for the organization control of steel materials, so it is expected to develop a new generation of processing heat treatment technology. The new generation of processing and heat treatment technology mentioned here is an area that has not been studied by TMCP technology in the past, and is characterized by:
　　(1) large strain processing centered on large reduction of one rolling pass;
　　(2) processing in the medium temperature region below 750 ℃. The large strain processing, including the medium temperature region, is to make full use of the strain accumulation effect by avoiding the strain recovery between rolling passes, and to maximize the control effect of recrystallization and phase change after processing. This large strain processing has the following characteristics:
　　1. It can effectively improve the driving force of phase change/recrystallization and greatly increase the generation density of crystal nuclei
　　2. Dynamic effects with stress-strain regions, such as dynamic recrystallization and dynamic phase transitions, etc.
　　3. It has a rapid heating effect accompanied by large processing heat. Because of these characteristics, large strain processing can produce 1 new metallurgical phenomena that have not been known so far. In addition, the STX21 project uses various slip systems to improve local strain concentration, thereby increasing the generation size of phase transition and recrystallization nuclei, while also pursuing a 1 multi-axis machining aimed at breaking the rules of variability.

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