| 摘要 |
PCT No. PCT/JP81/00281 Sec. 371 Date Jun. 9, 1982 Sec. 102(e) Date Jun. 9, 1982 PCT Filed Oct. 14, 1981 PCT Pub. No. WO82/01379 PCT Pub. Date Apr. 29, 1982.Dual-phase high-tensile steel sheets having a composite structure consisting of martensite and ferrite and a tensile strength of the order of 50-80 kg/mm2 in an as-hot-rolled state are produced by a method which comprises preparing as a starting material a slab comprising 0.03-0.15% C, 0.5-1.0% Mn, 0.8-2.0% Si, 0.6-2.0% Cr, 0.01-0.1% Al, the balance being essentially Fe and accompanying impurities, heating said slab at a temperature of 1,050 DEG -1,220 DEG C., hot rolling the heated slab, completing the hot rolling at a temperature of 800 DEG -900 DEG C., thereafter cooling the hot-rolled sheet to a temperature of 350 DEG -500 DEG C., and winding the sheet into a coil at the latter temperature. A proper combination of the above-mentioned steel composition, slab heating temperature prior to hot rolling, final hot rolling temperature and winding temperature allows hot-rolled dual-phase high-tensile steel sheets having improved formability and uniform mechanical properties to be produced at a low cost without adding expensive Mo. |
