冷镦钢 Cold heading quality steel | SWRCH6A~22A 10B21~10B38 15B25~15B54 20~30MnB4 SWRCH25K~45K ML20Cr~ML40Cr SCR420 SCM420 SCM435 SCM440 B7 20~42CrMo ML20MnTiB 51B20 | Φ5.5~26 | JIS 3507 ASTM A510 GB/T 6478 JIS 4053 | 用于制作4.8~12.9级紧固件。 Used for making fastener of Grade 4.8-12.9. |