Abstract
The process development to manufacture ultrafine grained steels has, recently, become a hot topic for researc all over the world. Ultrafine structure can be fabricated by the concept of "high Z - large strain deformation". Z expresses Zener - Hollomn parameter. Based on this concept, warm multi-pass caliber rolling technology and continuous rolling process has been developed. The ultrafine grained steels produced by these processes show excellent strength - formability balance.
