What are the common materials used for extension springs?

Jiu Sheng production of extension springs commonly used materials are mainly carbon spring steel, this price is cheaper, but the elastic limit is low; low manganese spring steel, with good strength and hardenability, but easy to produce cracks after quenching; silicomanganese spring steel, the elastic limit has been improved, but also has very good mechanical properties, chrome vanadium steel, toughness and strength are better, the price is also slightly expensive.