NON-HEAT TREATED STEEL FOR HOT FORGING AND STEEL FOR HOT ROLLING EXCELLENT IN FRACTURE SPLITTABILITY AND MACHINABILITY, AND HOT FORGING NON-HEAT TREATED STEEL PART

摘要

The invention provides a hot-forging micro-alloyed steel and a hot-rolled steel which achieve excellent fracture-splitability and machinability, without impairing productivity or mechanical properties and without addition of Pb or the like. It also provides a component made of hot-forged micro-alloyed steel. The hot-forging micro-alloyed steel comprises, in mass%, C: greater than 0.35 to 0.60%, Si: 0.50 to 2.50%, Mn: 0.20 to 2.00%, P: 0.010 to 0.150%, S: 0.040 to 0.150%, V: 0.10 to 0.50%, Zr: 0.0005 to 0.0050%, Ca: 0.0005 to 0.0050% and N: 0.0020 to 0.0200%, Al being limited to less than 0.010%, and a balance substantially of Fe and unavoidable impurities.