JIS G4105 is a Japanese Industrial Standard specifies chromium molybdenum steels, mainly for machine structural use. And it’s manufactured by hot forming, such hot rolled and forging, ordinarily used after further process of forging, cutting and heat treatment.

There are 10 classes or steel grades in this JIS G4105 specifications: SCM 415, SCM 418, SCM 420, SCM 421, SCM 430, SCM 432, SCM 435, SCM 440, SCM 445, SCM 822.