The principle of selecting and purchasing spring steel wire is: to meet the functional requirements first, then to meet the strength requirements, and finally to consider the economy.
Carbon spring steel is widely used in spring steel and its consumption is the largest. The steel contains 0.60% ～ 0.90% carbon and 0.3% ～ 1.20% manganese, so the cost is relatively low. After proper processing or heat treatment, high tensile strength, sufficient toughness and good fatigue life can be obtained. However, the carbon steel wire has low hardenability, poor relaxation resistance and corrosion resistance. The temperature coefficient of elastic modulus is large (up to 300 × 10-6 / ℃). It is suitable for manufacturing springs with small cross-section and low working temperature (120 ℃ >).
Alloy spring steel generally contains 0.45% – 0.70% carbon and a certain amount of Si, Mn, Cr, V, W and B alloy elements. The addition of alloying elements can improve the relaxation resistance and toughness of spring steel, and significantly improve the hardenability and service temperature of the steel. It is suitable for manufacturing springs with larger cross-section and higher temperature.