The application scope and process characteristics of various kinds of carbon spring steel wire are introduced according to the standard.
(1) Yb / t5220-93 carbon spring steel wire for non mechanical spring
The standard is applicable to carbon spring steel wire for non mechanical spring such as sofa cushion spring, cushion, back tension spring, clip spring and so on. The steel wire is divided into A1, A2, A3 according to different tensile strength requirements A9 nine groups, each group of steel wire regardless of size according to a strength range, tensile strength deviation ≤ 200MPa. Groups A1, A2 and A3 are used to make lower stress springs. A3, A4 and A5 are used to make general stress springs. A7, a8 and A9 are used to make high stress springs. Mattress spring is generally selected A3 and A4 groups.
According to the analysis of service state, the standard steel wire is basically a static spring, and the finished steel wire only has three properties of tensile strength, winding and single bending, and Yb / t5220-93 carbon spring steel wire for non mechanical spring
① The steel wire with diameter ≤ 4.0 mm is wound on the 2D mandrel for two times without crack or fracture.
② The steel wire with a diameter of more than 4.0 mm is subjected to bending test. The sample is bent for 90o along the arc of R = 10mm, and there is no crack or fracture at the bend. In general, 45-70 steel is selected for A1-A3 group, 65Mn or 70 steel is selected for a3-a6 group, and 70 or t8mna (82B) is selected for a7-a9 group steel wire. The steel wire can be used to control the fatigue life of the steel wire directly according to the requirements of the steel wire drawing plate. Normalizing can be used instead of lead bath in heat treatment of steel wire before forming. At the same time, converter killed steel is allowed to be used as raw material.
(2) GB / t4357-89 “carbon spring steel wire” is the general standard for cold drawn carbon spring steel wire, which is mainly used to make static spring working under various stress conditions. According to the working stress state of the spring, the steel wire can be supplied in three levels: Grade B for low stress spring, grade C for medium stress spring and grade D for high stress spring. The tensile strength, torsion, winding and bending properties of the finished steel wire are evaluated.