公开(公告)号：US20200240487A1

公开(公告)日：2020-07-30

申请号：US16604417

申请日：2018-04-10

Applicant: NHK SPRING CO., LTD.

Inventor： Toshiyuki AKANUMA ,  Tohru SHIRAISHI ,  Yohei IWAGAKI ,  Keita TAKAHASHI ,  Shun HIRAI

IPC: F16F1/02 ,  F16F1/06 ,  B21F3/06 ,  C21D9/02 ,  C21D8/06 ,  C21D1/06 ,  C23C8/22 ,  C21D6/00 ,  C22C38/46 ,  C22C38/24 ,  C22C38/22 ,  C22C38/02 ,  C22C38/04

Abstract: A compression coil spring includes a steel wire material containing, hereinafter in weight %, 0.5 to 0.7% of C, 1.2 to 3.0% of Si, 0.3 to 1.2% of Mn, 0.5 to 1.9% of Cr and 0.05 to 0.5% of V as necessary components, one or more kinds selected from not more than 1.5% of Ni, not more than 1.5% of Mo and not more than 0.5% of W as freely selected components, and iron and inevitable impurities as the remainder; the C-condensed layer which exceeds the average concentration of C contained in the steel wire material exists at a surface layer part, and the thickness of the C-condensed layer is within 0.01 to 0.05 mm along the entire circumference of the steel wire material.