| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a steel which performs reduction of deformation resistance and improvement of deformability, can demonstrate an excellent cold forgeability, and to provide a method of manufacturing the same. <P>SOLUTION: The steel includes, by mass: 0.15-0.6% of C; 0.05-0.6% of Si; 0.1-1.5% of Mn; at most 0.05% of P (excluding 0%); 0.001-0.05% of S; 0.01-0.5% of Cr; 0.01-0.1% of Al; at most 0.01% of N (excluding 0%); and a remnant comprising iron and indispensable impurities, and a metal structure of the steel includes cementite and ferrite, wherein a total area ratio of the cementite and the ferrite is at least 95 area% based on the total structure, an aspect ratio of at least 90% of the cementite is at most 3, and an average distance between weighted centers of the cementite is at least 1.5 μm, and further an average crystal particle diameter is 5-20 μm. <P>COPYRIGHT: (C)2012,JPO&INPIT |
