THE MANUFACTURING METHOD OF FERRITE STAINLESS STEEL WITH HIGH CORROSION RESISTANCE AND HIGH FORMABILITY

摘要

PURPOSE: A method for manufacturing ferritic stainless steel is provided to restrain nozzle clogging caused by titanium oxides during the continuous casting operation, surface defects, and tempered colors caused when bright annealing by adjusting the addition amount of Cr, Mo, and Cu in steel composition and optimizing (Nb+Ti)/(C+N) ratio and Nb/Ti ratio. CONSTITUTION: The manufacturing method of the ferritic stainless steel comprises the process of (i) heating a stainless steel comprising C 0.02wt.% or less, Si 0.5wt.% or less, Mn 0.5wt.% or less, P 0.03wt.% or less, S 0.003wt.% or less, Cr 17.5-23wt.%, Mo 4wt.% or less, N 0.02wt.% or less, Cu 0.3-0.7wt.%, Ti 0.6wt.% or less, Nb 0.6wt.% or less, a balance of Fe, and other inevitable impurities to the temperature range of 1150 to 1250deg.C; (ii) finish rolling in the temperature range of 750 to 900deg.C after hot rolling steel sheet; quenching after annealing hot rolled steel sheet in the temperature range of 900 to 1000deg.C; (iii) annealing cold rolled steel sheet in the temperature range of 900 to 1000deg.C after cold rolling; and then (iv) quenching. In the steel composition, C+N 0.03%, the content of Cr, Mo, and Cu in steel composition satisfies the follow equation: E'=43.9Cr%+15.9Mo%+26.7Cu%-550.5300, (Nb+Ti)/(C+N) ranges from 10 to 20, Nb/Ti is larger than 2.