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. (FIG. 1)