High-strength steel sheet for cans and method for manufacturing the same

Abstract

A steel sheet for cans that has a yield stress of at least 500 Mpa after coating and baking and a method for manufacturing the steel sheet for cans are provided. The steel sheet for cans contains, on the basis of mass percent, C: more than 0.02% but 0.10% or less, Si: 0.10% or less, Mn: 1.5% or less, P: 0.20% or less, S: 0.20% or less, Al: 0.10% or less, N: 0.0120% to 0.0250%, dissolved N being 0.0100% or more, and a remainder of Fe and incidental impurities. A high-strength material can be obtained by maintaining the absolute quantity of dissolved N at a certain value or more and performing hardening by quench aging and strain aging, for example, in a printing process, a film lamination process, or a drying and baking process performed before can manufacturing. In the manufacture, hot rolling is performed at a slab extraction temperature of 1200° C. or more and a finish rolling temperature of (Ar3 transformation temperature—30)° C. or more, and coiling is performed at 650° C. or less.

1 . A high-strength steel sheet for cans, comprising, on the basis of mass percent, C: more than 0.02% and 0.10% or less, Si: 0.10% or less, Mn: 1.5% or less, P: 0.20% or less, S: 0.20% or less, Al: 0.10% or less, N: 0.0120% to 0.250%, dissolved N being 0.0100% or more, and the balance being Fe and incidental impurities. 
     
     
         2 . The high-strength steel sheet for cans according to  claim 1 , wherein the high-strength steel sheet has a plated layer on the surface thereof. 
     
     
         3 . A method for manufacturing a high-strength steel sheet for cans, comprising: hot rolling a steel slab at a slab extraction temperature of 1200° C. or more and a finish rolling temperature of (Ar3 transformation temperature—30)° C. or more, the steel slab containing, on the basis of mass percent, C: more than 0.02% but 0.10% or less, Si: 0.10% or less, Mn: 1.5% or less, P: 0.20% or less, S: 0.20% or less, Al: 0.10% or less, N: 0.0120% to 0.0250%, and the balance being Fe and incidental impurities; coiling at a temperature of 650° C. or less; pickling; cold rolling; and then continuously annealing. 
     
     
         4 . The method for manufacturing a high-strength steel sheet for cans according to  claim 3 , further comprising second cold rolling at a reduction ratio of 10% or more and less than 20% after the continuous annealing. 
     
     
         5 . The method for manufacturing a high-strength steel sheet for cans according to  claim 3 , wherein the soaking temperature of the continuous annealing is equal to or higher than the Ar1 transformation temperature. 
     
     
         6 . The method for manufacturing a high-strength steel sheet for cans according to Claim  3 , further comprising plating after the continuous annealing or the second cold rolling. 
     
     
         7 . The method for manufacturing a high-strength steel sheet for cans according to  claim 4 , wherein the soaking temperature of the continuous annealing is equal to or higher than the Ar1 transformation temperature. 
     
     
         8 . The method for manufacturing a high-strength steel sheet for cans according to  claim 4 , further comprising plating after the continuous annealing or the second cold rolling. 
     
     
         9 . The method for manufacturing a high-strength steel sheet for cans according to  claim 5 , further comprising plating after the continuous annealing or the second cold rolling. 
     
     
         10 . The method for manufacturing a high-strength steel sheet for cans according to  claim 7 , further comprising plating after the continuous annealing or the second cold rolling.