Cold-rolled steel material and method for producing same
AssigneeHyundai Steel Company
InventorsSang Hun Shin, Kwang Su Na
Life of this patent
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Abstract
In one aspect, the present disclosure provides a cold-rolled steel material, wherein the cold-rolled steel material comprises, in weight %, carbon (C): 0.04% to 0.07%, silicon (Si): 0.1% to 0.3%, manganese (Mn): 1.1% to 1.5%, aluminum (Al): 0.015% to 0.06%, phosphorus (P): more than 0% and up to 0.02%, sulfur (S): more than 0% and up to 0.005%, niobium (Nb): 0.02% to 0.04%, titanium (Ti): 0.17% to 0.23%, chromium (Cr): more than 0% and up to 0.1%, nitrogen (N): more than 0% and up to 0.005%, and the balance being iron (Fe) and unavoidable impurities, and has a yield strength (YS) of 600 MPa to 900 MPa, an elongation (EL) of 8% or more, and a yield ratio (YR) of 95% or more.
Claims7
A cold-rolled steel material comprising, in weight %:
- carbon (C):
- 0.04% to 0.07%;
- silicon (Si):
- 0.1% to 0.3%;
- manganese (Mn):
- 1.1% to 1.5%;
- aluminum (Al):
- 0.015% to 0.06%;
- phosphorus (P):
- more than 0% and up to 0.02%;
- sulfur (S):
- more than 0% and up to 0.005%;
- niobium (Nb):
- 0.02% to 0.04%;
- titanium (Ti):
- 0.17% to 0.23%;
- chromium (Cr):
- more than 0% and up to 0.1%;
- nitrogen (N):
- more than 0% and up to 0.005%;
- and
- the balance being iron (Fe) and unavoidable impurities,
- wherein the cold-rolled steel material has a yield strength (YS) of 600 MPa to 900 MPa;
- an elongation (EL) of 8% or more;
- and a yield ratio (YR) of 95% or more.
A method of manufacturing a cold-rolled steel material, the method comprising:
- a) reheating a steel material comprising, in weight %, carbon (C):
- 0.04% to 0.07%, silicon (Si):
- 0.1% to 0.3%, manganese (Mn):
- 1.1% to 1.5%, aluminum (Al):
- 0.015% to 0.06%, phosphorus (P):
- more than 0% and up to 0.02%, sulfur (S):
- more than 0% and up to 0.005%, niobium (Nb):
- 0.02% to 0.04%, titanium (Ti):
- 0.17% to 0.23%, chromium (Cr):
- more than 0% and up to 0.1%, nitrogen (N):
- more than 0% and up to 0.005%, and the balance being iron (Fe) and unavoidable impurities, at a temperature of 1,200° C. to 1,250° C.;
- b) hot-rolling the heated steel material so as to finish at a temperature of Ar3 or higher;
- c) primary cooling the hot-rolled steel material;
- d) coiling the primary-cooled steel material at a coiling temperature of 580° C. to 620° C.;
- e) cold-rolling the coiled steel material to form a cold-rolled steel material;
- and
- f) annealing the cold-rolled steel material at an annealing temperature of 740° C. to 830° C.
Dependencies are inferred from the claim text.