Hot-rolled ferritic stainless steel sheet having excellent formability and method for manufacturing same

Abstract

The present invention pertains to a hot-rolled ferritic stainless steel sheet having excellent formability, which has an R-bar value of at least 1.08 and satisfies TS/YS≤1.5 representing the ratio of tensile strength (TS) to yield strength (YS) after a steel, containing 0.001-0.1% of C, 10.0-14.0% of Cr, 0.001-0.5% of Ti, 0.001-0.5% of Nb, 0.001-1.5% of Ni, 0.001-1.5% of Mn, 0.001-1.0% of Cu, 0.001-2.0% of Si, 0.001-0.1% of N, and 0.1% or less of Al, with the remainder comprising Fe and inevitable impurities, is hot-rolled and then pre-rolled at a reduction ratio of 30% or more.

1 . A hot-rolled ferritic stainless steel sheet with excellent formability having a value of R-bar being 1.08 or more and satisfying a ratio of yield strength (YS) and tensile strength (TS), TS/YS≤1.5, after hot rolling a steel comprising, in percent by weight (wt %), 0.001 to 0.1% of C, 10.0 to 14.0% of Cr, 0.001 to 0.5% of Ti, 0.001 to 0.5% of Nb, 0.001 to 1.5% of Ni, 0.001 to 1.5% of Mn, 0.001 to 1.0% of Cu, 0.001 to 2.0% of Si, 0.001 to 0.1% of N, 0.1% or less of Al and the remainder having Fe and unavoidable impurities and pre-rolling the steel at a reduction rate of 30% or more. 
     
     
         2 . The hot-rolled ferritic stainless steel sheet with excellent formability of  claim 1 , wherein a ferrite crystal grain size is 60 μm or less when the crystal grain size is measured in an electron backscattering diffraction analysis (EBSD) method with intergranular misorientation ranging from 15° to 180°. 
     
     
         3 . A method of manufacturing a hot-rolled ferritic stainless steel sheet with excellent formability, the method comprising:
 manufacturing a slab by continuously casting a steel comprising, in percent by weight (wt %), 0.001 to 0.1% of C, 10.0 to 14.0% of Cr, 0.001 to 0.5% of Ti, 0.001 to 0.5% of Nb, 0.001 to 1.5% of Ni, 0.001 to 1.5% of Mn, 0.001 to 1.0% of Cu, 0.001 to 2.0% of Si, 0.001 to 0.1% of N, 0.1% or less of Al and the remainder having Fe and unavoidable impurities;   reheating the manufactured slab;   hot rolling the reheated slab;   performing pre-rolling at a reduction rate of 30% or more to satisfy a value of R-bar being 1.08 or more and a ratio of yield strength (YS) and tensile strength (TS), TS/YS≤1.5; and   performing hot annealing.