| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide steel for a mechanical structure for cold working capable of achieving softening more than ever even when normal spheroidizing annealing is performed thereto, a useful method for manufacturing such steel for a mechanical structure for cold working, and a component for a mechanical structure obtained from such steel for a mechanical structure for cold working. <P>SOLUTION: This steel for a mechanical structure for cold working has a predetermined chemical component composition, wherein the metal structure of the steel contains pearlite and ferrite; the total area ratio of the pearlite and the ferrite to the entire structure is≥95 area%; the area ratio A of the ferrite satisfies A>Ae in a relationship with an Ae value represented by the following expression (1): Ae=(1.0-Ceq<SB POS="POST">1</SB>)×96.75, wherein Ceq<SB POS="POST">1</SB>=[C]+0.1×[Si]+0.06×[Mn], and [C], [Si] and [Mn] represent contents (mass%) of C, Si and Mn, respectively; and the average circle-equivalent diameter of bcc-Fe crystal grains surrounded by a high-angle boundary where orientation difference between two crystal grains adjacent to each other is larger than 15°is 15-35μm. <P>COPYRIGHT: (C)2013,JPO&INPIT</p> |
