MANUFACTURING METHODS OF FORMABLE BLACK PLATE WITH EXCELLENT WELDABILITY AND ANTI-FLUTING PROPERTIES

摘要

PURPOSE: A method for manufacturing a black plate with excellent weldability and anti-fluting properties for deep drawing is provided, which is characterized in that an ultra low carbon aluminum killed steel added with Ti and B to form carbonitride and further added with Cr is hot rolled, cold rolled and continuous annealed to improve anti-aging property. CONSTITUTION: The method includes the steps of soaking an aluminum killed steel comprising 0.005 wt.% or less of C, 0.010 wt.% or less of S, 0.003 wt.% or less of N, Mn 0.20 to 0.50 wt.%, Al 0.03 to 0.06 wt.%, B 0.0005 to 0.0020 wt.%, Ti 0.01 to 0.03 wt.%, Cr 0.02 to 0.06 wt.% and incidental impurities at 1200 to 1250 deg.C wherein effective atomic ratio of Ti/C is controlled within 0.4 to 1.2, and the amount of excess boron is regulated between 0.0001 to 0.0005 wt.%; finish hot rolling at right above Ar3 transformation temperature ranging from 900 to 920 deg.C; hot coiling the hot rolled steel sheet at 600 to 700 deg.C, followed by pickling; cold rolling it at a reduction ratio of 85 to 95 %; and continuous annealing the cold rolled steel sheet at 690 to 740 deg.C.