Corrosion resistance improved steel sheet for automotive muffler and method of producing the steel sheet

A steel sheet for an automotive muffler, comprising:

• 0.01% by weight or less of C;
• 0.1 to 0.3% by weight of Si;
• 0.3 to 0.5% by weight of Mn;
• 0.015% by weight or less of P;
• 0.015% or less by weight of S;
• 0.02 to 0.05% by weight of Al;
• 0.004% or less of N;
• 0.2 to 0.6% by weight of Cu;
• 0.01 to 0.04% by weight of Co;
• 0.2 to 0.4% by weight of Ni;
• and a remainder of Fe and unavoidable impurities,
• wherein 60−780*C(%)−15*Si(%)−20*Mn(%)−12*Cu(%)−10*Co(%)−10 Ni(%)≧35.

A steel sheet for an automotive muffler, comprising:

• 0.01% by weight or less of C;
• 0.1 to 0.3% by weight of Si;
• 0.3 to 0.5% by weight of Mn;
• 0.015% by weight or less of P;
• 0.015% or less by weight of S;
• 0.02 to 0.05% by weight of Al;
• 0.004% or less of N;
• 0.2 to 0.6% by weight of Cu;
• 0.01 to 0.04% by weight of Co;
• 0.05 to 0.2% by weight of Mo;
• and a remainder of Fe and unavoidable impurities,
• wherein 60−780*C(%)−15*Si(%)−20*Mn(%)−12*Cu(%)−10*Co(%)−8*Mo(%)≧35.

A steel sheet for an automotive muffler, comprising:

• 0.01% by weight or less of C;
• 0.1 to 0.3% by weight of Si;
• 0.3 to 0.5% by weight of Mn;
• 0.015% by weight or less of P;
• 0.015% or less by weight of S;
• 0.02 to 0.05% by weight of Al;
• 0.004% or less of N;
• 0.2 to 0.6% by weight of Cu;
• 0.01 to 0.04% by weight of Co;
• 0.1 to 0.3% by weight of Cr;
• and a remainder of Fe and unavoidable impurities,
• wherein 60−780*C(%)−15*Si(%)−20*Mn(%)−12*Cu(%)−10*Co(%)−8*Cr(%)≧35.

A steel sheet for an automotive muffler, comprising:

• 0.01% by weight or less of C;
• 0.1 to 0.3% by weight of Si;
• 0.3 to 0.5% by weight of Mn;
• 0.015% by weight or less of P;
• 0.015% or less by weight of S;
• 0.02 to 0.05% by weight of Al;
• 0.004% or less of N;
• 0.2 to 0.6% by weight of Cu;
• 0.01 to 0.04% by weight of Co;
• 0.2 to 0.4% by weight of Ni;
• 0.05 to 0.2% by weight of Mo;
• and a remainder of Fe and unavoidable impurities,
• wherein 60−780*C(%)−15*Si(%)−20*Mn(%)−12*Cu(%)−10*Co(%)−10*Ni(%)−8*Mo(%)≧35.

A steel sheet for an automotive muffler, comprising:

• 0.01% by weight or less of C;
• 0.1 to 0.3% by weight of Si;
• 0.3 to 0.5% by weight of Mn;
• 0.015% by weight or less of P;
• 0.015% or less by weight of S;
• 0.02 to 0.05% by weight of Al;
• 0.004% or less of N;
• 0.2 to 0.6% by weight of Cu;
• 0.01 to 0.04% by weight of Co;
• 0.2 to 0.4% by weight of Ni;
• 0.1 to 0.3% by weight of Cr;
• and a remainder of Fe and unavoidable impurities,
• wherein 60−780*C(%)−15*Si(%)−20*M (%)−12*Cu(%)−10*Co(%)−10*Ni(%)−8*Cr(%)≧35.

A steel sheet for an automotive muffler, comprising:

• 0.01% by weight or less of C;
• 0.1 to 0.3% by weight of Si;
• 0.3 to 0.5% by weight of Mn;
• 0.015% by weight or less of P;
• 0.015% or less by weight of S;
• 0.02 to 0.05% by weight of Al;
• 0.004% or less of N;
• 0.2 to 0.6% by weight of Cu;
• 0.01 to 0.04% by weight of Co;
• 0.05 to 0.2% by weight of Mo;
• 0.1 to 0.3% by weight of Cr;
• and a remainder of Fe and unavoidable impurities,
• wherein 60−780*C(%)−15*Si(%)−20*Mn(%)−12*Cu(%)−10*Co(%)−8*Mo(%)−8*Cr(%)≧35.

A steel sheet for an automotive muffler, comprising:

• 0.01% by weight or less of C;
• 0.1 to 0.3% by weight of Si;
• 0.3 to 0.5% by weight of Mn;
• 0.015% by weight or less of P;
• 0.015% or less by weight of S;
• 0.02 to 0.05% by weight of Al;
• 0.004% or less of N;
• 0.2 to 0.6% by weight of Cu;
• 0.01 to 0.04% by weight of Co;
• 0.2 to 0.4% by weight of Ni;
• 0.05 to 0.2% by weight of Mo;
• 0.1 to 0.3% by weight of Cr;
• and a remainder of Fe and unavoidable impurities,
• wherein 60−280*C(%)−15*Si(%)−20*Mn(%)−12*Cu(%)−10*Co(%)−10*Ni(%)−8*Mo(%)−8*Cr(%)≧35.

A method of producing a steel sheet for an automotive muffler, comprising:

• preparing a steel slab comprising 0.01% by weight or less of C;
• 0.1 to 0.3% by weight of Si;
• 0.3 to 0.5% by weight of Mn;
• 0.015% by weight or less of P;
• 0.015% or less by weight of S;
• 0.02 to 0.05% by weight of Al;
• 0.004% or less of N;
• 0.2 to 0.6% by weight of Cu;
• 0.01 to 0.04% by weight of Co;
• and a remainder of Fe and unavoidable impurities;
• preparing a hot rolled steel sheet by re-heating the steel slab followed by hot-rolling the steel slab, wherein the finishing rolling temperature is an Ar3 transformation temperature or more;
• preparing a cold rolled steel sheet by cold-rolling the hot rolled steel sheet with a cold reduction ratio of 50 to 90%;
• and
• performing a continuous annealing for the cold rolled steel sheet at a temperature of 500 to 900° C.,
• wherein 60−280*C(%)−15*Si(%)−20*Mn(%)−12*Cu(%)−10*Co(%)≧35.