Recent Progress of Rolling Technologies in Japan.

Abstract

After the Plaza Agreement of G5, which was held in September 1 985, the Yen was highly appreciated, and the Japanese governmentchanged its policy from the encouragement of exports to the expansion of the domestic market. Fortunately, the government policy has been a success, and the production of hot and cold strip, Iarge wide flange beam,wire and rod has recovered. Investment for equipment is under way and there a~e plans for renewing mills. However, the steel tube mills are highly dependent on the foreign market, the production of steel tube was drastically cut due to the sharp drop of the dollar and sharp rise of the yen. Nevertheless, research and development has been actively promoted and many marvelous results have been reported in every field. Iron and steel industries in Japan are still confident and innovative. KEYWORDS: review; rolling; plate mill; hot strip mill; cold strip mill; seamless tube mill; welded tube mil[; shape and section mill; wire and rod mill.

Effects of Edge Heating and Strain Gradient on Stretch Flange Deformation Limit of Steel Sheet

“…1) Among the problems in press forming of UHSS, stretch flange fracture has become apparent as a problem in mass production of automobile parts. 2) Stretch flange fracture is considered to be affected by the surface properties of the sheared edge of the material, 3) the work hardening near the sheared edge, 4) the hardness difference of the material microstructure, 5) etc. It has been reported that stretch flange formability decreases as the roughness and work hardening quantity of the sheared edge surface and the hardness difference of the microstructure increase.…”