Hard steel sheet manufactured from aluminium-killed continuous-cast carbon-manganese steel, and a method for the manufacture of such sheet.

摘要

Steel sheet manufactured from Al-killed continuous cast carbon-manganese steel and having a hardness in the range 57 to 73 HR30T is characterized by a content of 0.03 to 0.10% by weight C and 0.15 to 0.50% by weight Mn, and an amount Z in ppm of dissolved uncombined nitrogen given by
Z≧ 2.5 x (H-55)
where H is the hardness (HR30T). In this way, hard sheet is obtained at low Mn and C contents. In manufacture of the sheet, the thickness reduction in skin-passing is dependent on the uncombined nitrogencontent and an aging by heat treatment is performed after skin-passing.