| 摘要 |
PURPOSE: A method for manufacturing ferritic stainless steel is provided to improve formability and ridging resistance thereof by lowering theoretical yield strength, raising maximum gamma phase percentage, and controlling slab casting temperature optimal. CONSTITUTION: The ferritic stainless steel is manufactured by casting a steel comprising C 0.07wt.% or less, Si 0.4wt.% or less, Mn 1.0wt.% or less, P 0.035wt.% or less, S 0.002wt.% or less, Cr 15-20wt.%, Mo 0.5wt.% or less, N 0.05wt.% or less, Cu 0.6wt.% or less, Ni 0.4wt.% or less, Al 0.01wt.% or less, Ti 0.15wt.% or less, a balance of Fe, and other inevitable impurities at a casting temperature of 1536deg.C or lower; reheating the obtained steel slab in the temperature range of 1170 to 1250deg.C; finish hot rolling it in the temperature range of 750 to 900deg.C; annealing the hot rolled steel sheet in the temperature range of 860 to 900deg.C for 3-10 min; furnace cooling and pickling; cold rolling; annealing the cold rolled steel sheet in the temperature range of 860 to 900deg.C for 3-5 min; and then air cooling. The obtained ferritic stainless steel has a theoretical yield strength of 33.20 kg/mm2 or less and the theoretical yield strength is calculated by the follow equation: theoretical yield strength (kg/mm2) = 4.857+9.43Si+11.12Mn+81.73P+0.967Cr+6.99£Ti|+ 3.58Al+95.82£C+N|wherein in the case of Ti/(C+N)< 10,£Ti|is 0 and£C+N|is equal to (C+N)-Ti/10, however in the case of Ti/(C+N) >10,£Ti|is equal to Ti-10(C+N) and£C+N|is zero. Also, the ferritic stainless steel has a maximum gamma phase of 45% or higher and the maximum gamma phase is calculated by the follow equation: maximum gamma phase (%)=420(C%)+470(N%)+9(Cu%)+10(Mn%)+23(Ni%)-11.5(Cr%)-11.5(Si%)-12(Mo%)-49(Ti% )-52(Al%)+180.
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