Structural stainless steel sheet having excellent corrosion resistance at weld and method for manufacturing same

Abstract

A structural stainless steel sheet which can be manufactured at a low cost and with high efficiency, and possesses excellent welded-part corrosion resistance and a manufacturing method thereof are provided. The structural stainless steel sheet has a composition which contains by mass % 0.01 to 0.03% C, 0.01 to 0.03% N, 0.10 to 0.40% Si, 1.5 to 2.5% Mn, 0.04% or less P, 0.02% or less S, 0.05 to 0.15% Al, 10 to 13% Cr, 0.5 to 1.0% Ni, 4×(C+N) or more and 0.3% or less Ti, and Fe and unavoidable impurities as a balance, V, Ca and O in the unavoidable impurities being regulated to 0.05% or less V, 0.0030% or less Ca and 0.0080% or less O, wherein an F value expressed by Cr+2×Si+4×Ti−2×Ni−Mn−30×(C+N) satisfies a condition that F value≦11 and an FFV value expressed by Cr+3×Si+16×Ti+Mo+2×Al−2×Mn−4×(Ni+Cu)−40×(C+N)+20×V satisfies a condition that FFV value≦9.0.

1 . A structural stainless steel sheet having a composition which contains by mass % 0.01 to 0.03% C, 0.01 to 0.03% N, 0.10 to 0.40% Si, 1.5 to 2.5% Mn, 0.04% or less P, 0.02% or less 5, 0.05 to 0.15% Al, 10 to 13% Cr, 0.5 to 1.0% Ni, 4×(C+N) or more and 0.3% or less Ti (C, N indicating contents (mass %) of C and N), and Fe and unavoidable impurities as a balance, V, Ca and O in the unavoidable impurities being regulated to 0.05% or less V, 0.0030% or less Ca and 0.0080% or less O, wherein an F value and an FFV value expressed by following formulae satisfy a condition that F value≦11 and FFV value≦9.0.
     F  value=Cr+2×Si+4×Ti−2×Ni−Mn−30×(C+N)
 
     FFV  value=Cr+3×Si+16×Ti+Mo+2×Al−2×Mn−4×(Ni+Cu)−40×(C+N)+20×V
 
 In the formulae, the respective element symbols are contents of the elements (mass %). 
 
     
     
         2 . The structural stainless steel sheet further containing 1.0% or less Cu by mass % in addition to the components of  claim 1 . 
     
     
         3 . The structural stainless steel sheet further containing 1.0% or less Mo by mass % in addition to the components of  claim 1 . 
     
     
         4 . The method of manufacturing a structural stainless steel sheet, wherein a steel slab having a composition which contains by mass % 0.01 to 0.03% C, 0.01 to 0.03% N, 0.10 to 0.40% Si, 1.5 to 2.5% Mn, 0.04% or less P, 0.02% or less S, 0.05 to 0.15% Al, 10 to 13% Cr, 0.5 to 1.0% Ni, 4×(C+N) or more and 0.3% or less Ti (C, N indicating contents (mass %) of C and N), and Fe and unavoidable impurities as a balance, V, Ca and O in the unavoidable impurities being regulated to 0.05% or less V, 0.0030% or less Ca and 0.0080% or less O, wherein an F value and an FFV value expressed by following formulae satisfy a condition that F value≦11 and FFV value≦9.0 is heated at a temperature of 1100° C. to 1300° C. and, thereafter, hot rolling which includes a rough hot rolling where rolling is performed for at least 1 pass or more at a reduction rate of 30% or more in a temperature range exceeding 1000° C., or the hot rolling is performed without annealing the hot-rolled sheet or after annealing the hot-rolled sheet at a temperature of 600 to 1000° C. and, thereafter, pickling is applied to the hot-rolled sheet or the annealed hot-rolled sheet.
     F  value=Cr+2×Si+4×Ti−2×Ni−Mn−30×(C+N)
 
     FFV  value=Cr+3×Si+16×Ti+Mo+2×Al−2×Mn−4×(Ni+Cu)−40×(C+N)+20×V
 
 In the formulae, the respective element symbols are contents of the elements (mass %). 
 
     
     
         5 . The method of manufacturing a structural stainless steel sheet further containing 1.0% or less Cu by mass % in addition to the components of the steel slab according to  claim 4 . 
     
     
         6 . The method of manufacturing a structural stainless steel sheet further containing 1.0% or less Mo by mass % in addition to the components of the steel slab according to  claim 4 . 
     
     
         7 . The structural stainless steel sheet further containing 1.0% or less Mo by mass % in addition to the components of  claim 2 . 
     
     
         8 . The method of manufacturing a structural stainless steel sheet further containing 1.0% or less Mo by mass % in addition to the components of the steel slab according to  claim 5 .