How to distinguish between raw silk and ripe silk for springs?

(1) Raw silk: Raw silk is a type of cold drawn steel wire that has not undergone lead bath heat treatment. After cold drawing, its internal structure is damaged and leaves a large amount of tensile stress. After making the tension spring, it must be tempered as soon as possible. Mainly used for ordinary low stress, low load tension springs (such as mattress springs, seat cushion springs, snap springs, and other non mechanical tension springs). The diameter range of raw silk is generally above 2.0 millimeters.
 
(2) Mature wire: After lead bath heat treatment, tempered martensite structure is obtained, and the steel wire structure is loaded with fibers. The tensile strength of the drawn steel wire is not significantly different from that of raw silk. But after lead bath treatment, the elastic limit, bending and torsional resistance, and fatigue relaxation resistance of the material have been greatly improved. Steel wires with a diameter less than 1.0 mm are generally mature steel wires, mainly used for mechanical tension springs under medium stress loads