Steel sheet for crown cap, method for manufacturing same, and crown cap

Abstract

A steel sheet for crown caps includes C: 0.0005 to 0.0050%, Si: 0.020% or less, Mn: 0.10 to 0.60%, P: 0.020% or less, S: 0.020% or less, Al: 0.01 to 0.10%, N: 0.0050% or less, Nb: 0.010 to 0.050%, and Fe and inevitable impurities. The steel sheet has an average r value of 1.30 or more and a YP of 450 MPa or more and 650 MPa or less. The steel sheet is obtained by hot rolling a steel slab at a slab reheating temperature of 1,150° C. or higher and a finishing temperature of 870° C. or higher; coiling the hot rolled steel sheet at a coiling temperature of 600° C. or higher, performing pickling; then-performing primary cold rolling; performing annealing at an annealing temperature of recrystallization temperature or more and 790° ° C. or less; and performing secondary cold rolling at a rolling reduction of 10% or more and 50% or less.

1 . A steel sheet for crown caps, the steel sheet comprising:
 C: 0.0005 to 0.0050%, by mass %:   Si: 0.020% or less, by mass %:   Mn: 0.10 to 0.60%, by mass %:   P: 0.020% or less, by mass %;   S: 0.020% or less, by mass %:   Al: 0.01 to 0.10%, by mass %:   N: 0.0050% or less, by mass %:   Nb: 0.010 to 0.050%, by mass %; and   Fe and inevitable impurities,   wherein the steel sheet has an average r value of 1.30 or more and a YP of 450 MPa or more and 650 MPa or less.   
     
     
         2 . The steel sheet for crown caps according to  claim 1 , wherein an elongation rate of ferrite in the steel sheet is 4.2 or less. 
     
     
         3 . A method for manufacturing a steel sheet for crown caps, the method comprising:
 hot rolling a steel slab at a slab reheating temperature of 1,150° C. or higher and a finishing temperature of 870° C. or higher,
 the steel slab having a chemical composition including:
 C: 0.0005 to 0.0050%, by mass %: 
 Si: 0.020% or less, by mass %: 
 Mn: 0.10 to 0.60%, by mass %; 
 P: 0.020% or less, by mass %: 
 S: 0.020% or less, by mass %: 
 Al: 0.01 to 0.10%, by mass %: 
 N: 0.0050% or less, by mass %: 
 Nb: 0.010 to 0.050%, by mass %; and 
 Fe and inevitable impurities: 
 
   coiling the hot rolled steel sheet at a coiling temperature of 600° C. or higher;   performing pickling on the coiled steel sheet;   then, after the pickling, performing primary cold rolling;   performing annealing at an annealing temperature of recrystallization temperature or more and 790° C. or less; and   then, after the annealing, performing secondary cold rolling at a rolling reduction of 10% or more and 50% or less.   
     
     
         4 . A crown cap formed of a steel sheet, the steel sheet comprising:
 C: 0.0005 to 0.0050%, by mass %:   Si: 0.020% or less, by mass %:   Mn: 0.10 to 0.60%, by mass %;   P: 0.020% or less, by mass %;   S: 0.020% or less, by mass %;   Al: 0.01 to 0.10%, by mass %;   N: 0.0050% or less, by mass %;   Nb: 0.010 to 0.050%, by mass %; and   Fe and inevitable impurities,   wherein the steel sheet has an average r value of 1.30 or more and a YP of 450 MPa or more and 650 MPa or less.   
     
     
         5 . The steel sheet for crown caps according to  claim 1 , wherein the steel sheet has an average thickness from about 0.13 mm to about 0.22 mm. 
     
     
         6 . The crown cap according to  claim 4 , wherein the steel sheet has an average thickness from about 0.13 mm to about 0.22 mm. 
     
     
         7 . The crown cap according to  claim 4 , wherein the steel sheet has an elongation ratio of ferrite being 4.2 or less.