In other words, the internal structure of cold drawn steel wire without lead bath heat treatment is destroyed after cold drawing, and a large amount of drawing stress remains. After being made into spring, it must be tempered as soon as possible. It is mainly used for ordinary low stress and low load spring (such as mattress spring, seat cushion spring, clip spring, clip spring, etc.), and the wire diameter range of raw wire is generally more than 2.0 mm.
That is to say, after heat treatment in lead bath, tempered sorbite structure is obtained, and the steel wire structure is in the form of fiber. After drawing, the tensile strength of steel wire is not much different from that of raw wire. However, the elastic limit, bending and torsion resistance, fatigue relaxation resistance of the material after lead bath treatment are improved greatly. Generally, the steel wire less than 1.0 mm wire diameter is cooked wire, which is mainly used for Medium stress load mechanical spring, precision spring, etc.
Lead bath heat treatment
Scope of application
Wire diameter range
The internal organizational structure was destroyed
Mattress spring, cushion spring, clip spring and other non mechanical springs
Above 2.0 mm
After heat treatment, the internal structure presents fibrous tempered sorbite
Medium stress load, static spring
All below 1.0 mm are cooked silk