Patent ID: 10323293

Abstract:
A high-carbon hot rolled steel sheet with excellent hardenability and small in-plane anisotropy, and a method for manufacturing the steel sheet are provided. The steel sheet has a chemical composition including, by mass %, C: 0.20 to 0.48%, Si: not more than 0.1%, Mn: not more than 0.5%, P: not more than 0.03%, S: not more than 0.01%, sol. Al: not more than 0.10%, N: not more than 0.005% and B: 0.0005 to 0.0050%, the balance including Fe and inevitable impurities. The steel sheet includes a microstructure containing ferrite and cementite. The cementite has an average grain size of not more than 1.0 μm. The steel sheet has an in-plane anisotropy of r value, Δr, of not more than 0.1 in absolute value.