| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a forged part, in which a portion with sufficient yield strength, and a portion with suppressed yield strength for improving cutting workability are formed in a part, in a non-heat treated state. <P>SOLUTION: The method for manufacturing the forged part includes: a heating treatment step heating workpiece material to be from T<SB POS="POST">VC</SB>+50°C or higher to 1,350°C or lower; a hot forging step performing hot forging of the workpiece material to be from A<SB POS="POST">C3</SB>point or higher to 950°C or lower, in which an equivalent strain quantity is 0.2 or larger; and a cooling step cooling the workpiece material, wherein: in a high-strength portion, a mean cooling rate from a temperature of the workpiece material when the hot forging step is finished to a rapid cooling stopping temperature is 3.0°C/s or higher, and a mean cooling rate from the rapid cooling stopping temperature to 500°C is from 0.5°C/s or higher to 2.0°C/s or lower; and in a low-strength portion, a mean cooling rate from a temperature when the hot forging step is finished to 500°C is 1.0°C/s or lower. <P>COPYRIGHT: (C)2012,JPO&INPIT |
