Patent attributes
The present invention provides a steel sheet with chemical components including, by mass %, 0.18-0.35% of C, 1.0%-3.0% of Mn, 0.01%-1.0% of Si, 0.001%-0.02% of P, 0.0005%-0.01% of S, 0.001%-0.01% of N, 0.01%-1.0% of Al, 0.005%-0.2% of Ti, 0.0002%-0.005% of B, and 0.002%-2.0% of Cr, and the balance of Fe and inevitable impurities, wherein: by volume %, a fraction of the ferrite is 50% or more, and a fraction of a non-recrystallized ferrite is 30% or less; and Crθ/CrM is 2 or less, where Crθ is a concentration of Cr subjected to solid solution in iron carbide and CrM is a concentration of Cr subjected to solid solution in a base material, or Mn0/MnM is 10 or less, where Mn0 is a concentration of Mn subjected to solid solution in an iron carbide, and MnM is a concentration of Mn subjected to solid solution in a base material.
