AISI 1045 steel is a high-strength high-quality medium carbon steel. Also known as JIS S45C and din C45 steel. Because of its poor hardenability, it is usually used in normalized state. Quenching and tempering treatment is needed to obtain higher mechanical properties. Used for manufacturing mechanical parts with high strength requirements. Such as gears, shafts, piston pins, etc.

It has good weldability and machinability. After normalizing and hot rolling, high strength and impact properties will be obtained. The hardenability is low, and the critical hardenability diameter in water is 12-17mm. And it tends to crack during water quenching. Hydrogen welding and argon arc welding are good for it, but gas welding is not. Preheating is required before welding, and stress relief annealing shall be carried out after welding.