Introduction to JIS G 4051 Carbon Steels for Machinery

JIS G 4051 is a Japanese standard that specifies carbon steels used for machine structural purposes. The steels covered under this standard are typically used in the manufacturing of shafts, gears, bolts, pins, and other mechanical components.
The most common grades include S15C, S35C, S45C, and S55C. Each grade represents a different carbon content, which affects the hardness, strength, and machinability of the material.
S45C is the most widely used grade because it offers a good balance of strength and workability. These steels can be delivered as hot-rolled, normalized, or cold-drawn depending on the application.
JIS G 4051 steels are widely used in Japan and other Asian countries and are often cross-referenced with standards such as SAE 1045 or DIN C45.