METHOD OF MANUFACTURING FERRITE-PEARLITE TYPE NON-TEMPERED FORGED PART

摘要

PROBLEM TO BE SOLVED: To provide a method of manufacturing a forged part, with which both of a portion (highly strengthened portion) to which sufficient yield strength is given and a portion (low strengthened portion) in which the yield strength is suppressed in order to improve cutting workability, are formed in a non-tempered manner in one part.;SOLUTION: The method of manufacturing the forged part includes: a heat-treating step in which the highly strengthened portion of a workpiece is heated to T_VC+50°C or higher and the low strengthened portion of the workpiece is heated to A_C3 point to T_VC-50°C; a hot forging step in which the highly strengthened portion is subjected to hot forging at 1,050°C or higher to the heating temperature or lower, and the low strengthened portion is subjected to hot forging at A_C3 point or more; and a cooling step in which the workpiece is cooled in such a manner that the average cooling rate is 0.5-2.0°C/s for the highly strengthened portion, and the average cooling rate is 10°C/s or less for the low strengthened portion.;COPYRIGHT: (C)2012,JPO&INPIT