| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a medium-carbon steel plate containing 0.3-0.55 mass% of C and exhibiting excellent rapid heating/quenching property after cold forging, and to provide a quenching method of thereof. <P>SOLUTION: The medium-carbon steel plate includes: 0.30-0.55 mass% of C; 0.05-0.3 mass% of Si; 0.3-1.5 mass% of Mn; 0.005-0.03 mass% of P; 0.0001-0.01 mass% of S; 0.005-0.10 mass% of Al; 0.001-0.01 mass% of N; and the balance Fe with inevitable impurities. In the medium-carbon steel plate, a mean circle-equivalent diameter of carbides is 0.25-0.65μm, and a spheroidizing ratio of the carbides is 60-90%. In the quenching method of the medium-carbon steel plate, hardening to 550 HV or more is carried out by performing rapid heating/quenching of the steel plate at 50°C/sec or more from room temperature to a quenching target temperature after cold forging. <P>COPYRIGHT: (C)2012,JPO&INPIT</p> |
