A steel sheet for a can having high strength, excellent ductility, and good corrosion resistance, and a method for manufacturing the steel sheet. The steel sheet has a chemical composition containing, by mass %, C: 0.020% or more and 0.130% or less, Si: 0.04% or less, Mn: 0.10% or more and 1.20% or less, P: 0.007% or more and 0.100% or less, S: 0.030% or less, Al: 0.001% or more and 0.100% or less, N: more than 0.0120% and 0.0200% or less, Nb: 0.0060% or more and 0.0300% or less, and Fe and inevitable impurities. An absolute value of a difference in an amount of solid solution Nb between a region from a surface to a position located at of a thickness and a region from a position located at of the thickness to a position located at 4/8 of the thickness is 0.0010 mass % or more.

A steel sheet for cans has a chemical composition containing, by mass %, C: 0.015% or more and 0.150% or less, Si: 0.04% or less, Mn: 1.0% or more and 2.0% or less, P: 0.025% or less, S: 0.015% or less, Al: 0.01% or more and 0.10% or less, N: 0.0005% or more and less than 0.0050%, Ti: 0.003% or more and 0.015% or less, B: 0.0010% or more and 0.0040% or less, and the balance being Fe and inevitable impurities. The steel sheet has a microstructure including a ferrite phase as a main phase and at least one of a martensite phase and a retained austenite phase as a second phase, the total area fraction of the second phase being 1.0% or more, and the sheet has a tensile strength of 480 MPa or more, a total elongation of 12% or more, and a yield elongation of 2.0% or less.

Provided is a steel sheet having sufficient formability and strength even after sheet metal thinning, the steel sheet including: a chemical composition containing, by mass %, C: more than 0.0060% and not more than 0.012%, Si: 0.02% or less, Mn: 0.10% or more and 0.60% or less, P: 0.020% or less, S: 0.020% or less, Al: 0.01% or more and 0.07% or less, and N: 0.0080% or more and 0.0200% or less, with the balance being Fe and inevitable impurities, in which a dislocation density at a depth position of of a sheet thickness from a surface of the steel sheet is 2.010.sup.14/m.sup.2 or more and 1.010.sup.15/m.sup.2 or less.

The present invention relates generally to steel compositions, methods of manufacturing the compositions and using the compositions to produce rimfire ammunition cartridges. The steel compositions for use in the rimfire cartridges are processed through cold-rolling and annealing steps to create suitable physical properties.

The present invention relates generally to steel compositions, methods of manufacturing the compositions and using the compositions to produce rimfire ammunition cartridges. The steel compositions for use in the rimfire cartridges are processed through cold-rolling and annealing steps to create suitable physical properties.

Provided is a steel sheet having sufficient formability and strength even after sheet metal thinning, the steel sheet including: a chemical composition containing, by mass %, C: more than 0.0060% and not more than 0.012%, Si: 0.02% or less, Mn: 0.10% or more and 0.60% or less, P: 0.020% or less, S: 0.020% or less, Al: 0.01% or more and 0.07% or less, and N: 0.0080% or more and 0.0200% or less, with the balance being Fe and inevitable impurities, in which a dislocation density at a depth position of of a sheet thickness from a surface of the steel sheet is 2.010.sup.14/m.sup.2 or more and 1.010.sup.15/m.sup.2 or less.

The present invention provides steel compositions, methods of manufacturing the compositions and using the compositions to produce rimfire ammunition cartridges. The steel compositions are substitutes for conventional brass used in the manufacture of rimfire ammunition cartridges and, in particular, for use in .22 caliber firing devices. Also provided are methods of processing and treating the steel compositions for use in the rimfire cartridges that include cold-rolling and annealing steps to create suitable physical properties.

A method for the manufacture of a cold rolled, recovered TWIP steel sheet coated with a metallic coating is provided including the following steps: (A) the feeding of a slab having the following composition : 0.1<C<1.2%, 13.0Mn<25.0%, S0.030%, P0.080%, N0.1%, Si3.0%, and on a purely optional basis, one or more elements such as Nb0.5%, B0.005%, Cr1.0%, Mo0.40%, Ni1.0%, Cu5.0%, Ti0.5%, V2.5%, Al4.0%, 0.06Sn0.2%, the remainder of the composition making up of iron and inevitable impurities resulting from elaboration; (B) Reheating such slab and hot rolling it; (C) A coiling step; (D) A first cold-rolling; (E) A recrystallization annealing; (F) A second cold-rolling; and (G) A recovery heat treatment performed by hot-dip coating.

A cold rolled and annealed steel sheet includes by weight: 0.6<C<1.3%, 15.0Mn<35%, 6.0Al<15%, Si2.40%, S0.015%, P0.1%, N0.1%, optionally one or more elements chosen among Ni, Cr and Cu in an individual amount of up to 3% and optionally one or more elements chosen among B, Ta, Zr, Nb, V, Ti, Mo, and W in a cumulated amount of up to 2.0%, the remainder of the composition making up of iron and inevitable impurities resulting from elaboration, a microstructure of said sheet comprising at least 0.1% of intragranular kappa carbides, wherein at least 80% of said kappa carbides have an average size below 30 nm, optionally up to 10% of granular ferrite, the remainder being made of austenite, an average grain size of the austenite being below 6 m, an average aspect ratio of the austenite being between 1.5 and 6, an average grain size of the ferrite, when present being below 5 m, and an average aspect ratio of the ferrite, when present, being below 3.0.

A cold rolled and annealed steel sheet including by weight: 0.6<C<1.3%, 15?Mn<35%, 6?Al<15%, Si?2.40%, S?0.03%, P?0.1%, N?0.1%, possibly one or more optional elements chosen among Ni, Cr and Cu in an individual amount of up to 3% and possibly one or more elements chosen among B, Ta, Zr, Nb, V, Ti, Mo, and W in a cumulated amount of up to 2.0%, the remainder of the composition making up of iron and inevitable impurities resulting from the elaboration, the microstructure of the sheet including of ordered ferrite between 1% and 10%, optionally of up to 10% of kappa carbides, the remainder being made of austenite, and, the density of the steel sheet being equal or below 7.2 and the FWHM for the austenite matrix is between 0.700 and 1.100.