High tensile strength steel for container and producing method of the same

Abstract

A steel sheet for containers that has a hardness of 500 MPa or more and superior workability and a method for producing the steel sheet are provided. A steel containing, in percent by mass, 0.01% to 0.05% carbon, 0.04% or less silicon, 0.1% to 1.2% manganese, 0.10% or less sulfur, 0.001% to 0.100% aluminum, 0.10% or less nitrogen, and 0.0020% to 0.100% phosphorus, the balance being iron and incidental impurities, is subjected to hot rolling at a finishing temperature of (Ar 3 transformation temperatute−30)° C. or more and a coiling temperature of 400° C. to 750° C., is subjected to pickling and cold rolling, is subjected to continuous annealing including overaging treatment, and is subjected to second cold rolling at a reduction rate of 20% to 50%, thus providing a high-strength steel sheet for containers that has a tensile strength of 500 MPa or more and a proof stress difference between width and rolling directions of 20 MPa or less.

1 . A high-strength steel sheet for containers, containing, in percent by mass, 0.01% to 0.05% carbon, 0.04% or less silicon, 0.1% to 1.2% manganese, 0.10% or less sulfur, 0.001% to 0.100% aluminum, 0.10% or less nitrogen, and 0.0020% to 0.100% phosphorus, the balance being iron and incidental impurities, the steel sheet having a tensile strength TS of 500 MPa or more and a proof stress difference between width and rolling directions of 20 MPa or less. 
     
     
         2 . A high-strength steel sheet for containers, containing, in percent by mass, 0.01% to 0.05% carbon, 0.04% or less silicon, 0.1% to 1.2% manganese, 0.10% or less sulfur, 0.001% to 0.100% aluminum, 0.10% or less nitrogen, and 0.0020% to 0.020% phosphorus, the balance being iron and incidental impurities, the steel sheet having a tensile strength TS of 500 MPa or more and a proof stress difference between width and rolling directions of 20 MPa or less. 
     
     
         3 . A method for producing a high-strength steel sheet for containers, wherein a steel containing, in percent by mass, 0.01% to 0.05% carbon, 0.04% or less silicon, 0.1% to 1.2% manganese, 0.10% or less sulfur, 0.001% to 0.100% aluminum, 0.10% or less nitrogen, and 0.0020% to 0.100% phosphorus, the balance being iron and incidental impurities, is subjected to hot roiling at a finishing temperature of (Ar 3  transformation temperature−30)° C. or more and a coiling temperature of 400° C. to 750° C., is subjected to pickling and cold rolling, is subjected to continuous annealing including overaging treatment, and is subjected to second cold rolling at a reduction rate of 20% to 50%. 
     
     
         4 . A method for producing a high-strength steel sheet for containers, wherein a steel containing, in percent by mass, 0.01% to 0.05% carbon, 0.04% or less silicon, 0.1% to 1.2% manganese, 0.10% or less sulfur, 0.001% to 0.100% aluminum, 0.10% or less nitrogen, and 0.0020% to 0.020% phosphorus, the balance being iron and incidental impurities, is subjected to hot rolling at a finishing temperature of (Ar 3  transformation temperature−30)° C. or more and a coiling temperature of 400° C. to 750° C., is subjected to pickling and cold rolling, is subjected to continuous annealing including overaging treatment, and is subjected to second cold rolling at a reduction rate of 20% to 50%.