Patent ID: 6858101

Claim:
An as-hot rolled or as-hot forged steel bar or rod excellent in forgeability and machineability, characterized in that; the steel bar or rod has a composition consisting essentially of, in mass %, C: 0.1-0.85%, Si: 0.01-1.5%, Mn: 0.05-2.0%, P: 0.003-0.2%, S: 0.003-0.5%, and Zr: 0.0003-0.01%, and Al, total O and total N are controlled in the respective ranges Al: 0.01% or less, total O: 0.02% or less, and total N: 0.0063% or less, and the average aspect ratio of MnS particles is 10 or less and the maximum aspect ratio of MnS particles is 30 or less; and the maximum particle size (μm) of MnS is equal to less than 110×[S %]+15 and the number of the MnS particles per mm 2 is not greater than 1657; and the balance of the steel components being Fe and unavoidable impurities.