2008 Volume 48 Issue 8 Pages 1133-1141
A national project was conducted by NEDO and executed by a consortium organized by JRCM with aims to develop integrated production technologies necessary for manufacturing ultra-fine grained steel (UFGS) sheets. In the project, the diverse technologies were concurrently developed relating with (1) high-speed large-reduction semi-continuous hot forging, (2) high-speed short-interval hot tandem rolling, (3) multi-cycle hot bending for strain accumulation, (4) high-strength anti-wear rolls, (5) multi-functional lubricants, (6) mathematical modeling and simulation of ultra-fine grain generation and (7) joining of UFGS sheets. The project succeeded in building up the integration of advanced technologies available for overall steel sheets manufacturing as well as production of UFGS sheets. Utilizing the developed technologies, UFGS sheets of plain low carbon steel having 1.0–2.0 mm thickness, 300 mm width, 1.0 μm grain diameter and 600–700 MPa tensile strength were successfully manufactured and found assuredly formable to practical products.