Patent ID: 10253384

Abstract:
A cold-rolled steel sheet includes, by mass %: C: 0.020% or more and 0.080% or less; Si: 0.20% or more and 1.00% or less; Mn: 0.80% or more and 2.30% or less; and Al: 0.010% or more and 0.100% or less; and further includes: one or more of Nb and Ti which satisfy a requirement of 0.005%≤Nb+Ti<0.030%, in which a structure consists of, ferrite, bainite, and other phases, an area ratio of the ferrite is 80% or more and less than 95%, an area ratio of a non-recrystallization ferrite in the ferrite is 1% or more and less than 10%, an area ratio of the bainite is 5% or more and 20% or less, a total amount of the other phases is less than 8%, an equivalent circle diameter of a carbonitride including one or both of Nb and Ti is 1 nm or more and 10 nm or less, and a tensile strength is 590 MPa or more.