PROCESS FOR IMPROVING THE COLD FORMABILITY OF HEAT-TREATABLE STEELS

摘要

The invention relates to a process for improving the cold formability of hot rolled or cold rolled heat-treatable steels. The characterizing feature of the invention is that with a composition of (in % by weight) 0.32-0.54% C 0.05-0.40% Mn 0.41-1.5% Si 0.02-0.15% Al maximum 0.05% Cr maximum 0.05% S maximum 0.03% P maximum 0.02% N residue iron and unavoidable impurities prior to the final cold forming and quench hardening with subsequent tempering is performed for at least 15 hours at temperatures between 620 DEG and 680 DEG C. to graphitization, while with a composition of 0.55-1.3% C 0.20-0.30% Mn 0.41-0.90% Si 0.02-0.15% Al maximum 0.05% Cr maximum 0.010% S maximum 0.03% P maximum 0.02% N residue iron and unavoidable impurities said annealing lasts for at least 8 hours.