| 摘要 |
Provided is a high-carbon hot-rolled steel sheet, the material of which is steel to which B has been added, which exhibits consistently excellent hardenability even when annealing is conducted in a nitrogen atmosphere, and which has excellent workability, such that prior to the hardening process, total elongation at an HRB of 83 or less is 30% or greater, or total elongation at an HRB of 75 or less is 30% or greater. The high-carbon hot-rolled steel sheet contains C: 0.20%-0.53%, Si: 0.10% or less, Mn: 0.50% or less, P: 0.03% or less, S: 0.010% or less, sol. Al: 0.10% or less, N: 0.0050% or less, and B: 0.0005%-0.0050%, and further contains a total of 0.002%-0.030% of one or more of the elements Sb, Sn, Bi, Ge, Te, and Se, and has a microstructure comprising ferrite and cementite, in which, when C is more than 0.40% but not more than 0.53%, the cementite density within the ferrite grains is 0.15/μm2 or fewer, or when C 0.20%-0.40%, the cementite density within the ferrite grains is 0.10/μm2 or fewer. |
