Patent ID: 6663730
Filing Date: 2003-12-16
Classification: C21D,C22C

Abstract:
A process for manufacturing a strip or of a part cut out of a strip of cold-rolled maraging steel and hardened by a hardening heat treatment, wherein, before the hardening heat treatment is performed, the strip or the part is subjected to cold plastic deformation with a degree of working greater than 30% and the strip or the part is subjected to recrystallization annealing in order to obtain a fine-grained structure with ASTM index higher than 8, the chemical composition of the steel comprising in % by weight based on total weight:12%&lE;Ni&lE;24.5% 2.5%&lE;Mo&lE;12% 4.17%&lE;Co&lE;20% Al&lE;0.15% Ti&lE;0.1% N&lE;0.003% Si&lE;0.1% Mn&lE;0.1% C&lE;0.005% S&lE;0.001% P&lE;0.005% H&lE;0.0003% O&lE;0.001%; and iron and impurities resulting from smelting, the chemical composition also satisfying the following relationships: 20%&lE;Ni+Mo&lE;27% 50&lE;CoÃ—Mo&lE;200 TiÃ—N&lE;2Ã—10âˆ’4.