| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel material for cold forging excellent in machinability after cold forging, obtained by softening a hot rolled steel bar or wire.SOLUTION: The steel material for cold forging contains C of 0.10 to 0.3%, Si of 0.05 to 1.0%, Mn of 0.4 to 2.0%, S of 0.003 to 0.05%. Cr of 0.5 to 3.0%, N of 0.010 to 0.025% and Al of 0.02 to 0.05% and the balance Fe with impurities, P, Ti and O in the impurities having chemical compositions of P≤0.025%, Ti≤0.003% and O≤0.002%, a micro structure comprising a ferrite+cementite structure, an average aspect ratio of cementite having a long diameter of 0.5 μm or longer being 5 or more and less than 10. The steel material may contain a specific amount of one or more kind of Cu, Ni, Mo, Nb and V in place of a portion of Fe. |
