Compression spring can be divided into static spring and dynamic spring according to the running state.Static spring refers to spring with limited vibration times during service, such as safety valve spring, spring pad, scale spring, fixed load spring, mechanical spring, watch spring, etc. Dynamic spring refers to springs with more than 1×106 times of vibration during service, such as engine valve spring, vehicle suspension spring, shockproof spring, coupling spring, elevator buffer spring, etc. Static spring material selection mainly consider tensile strength and stability, dynamic spring material selection mainly consider fatigue, relaxation and resonance performance.