Specification for special purpose carbon spring steel wire
① The tensile strength difference between the two ends of each steel wire shall not be greater than 100MPa.
② When the steel wire is twisted, there shall be no visible crack and delamination within the specified torsion times.
③ The steel wire shall not be broken or broken after winding 1-5 turns around the mandrel. The diameter of the mandrel is equal to the diameter of the wire.
(5) Yb / t5103-93 oil quenched tempered carbon spring steel wire
Oil quenched and tempered steel wire shall be produced to the size of finished product, and then oil quenched and tempered steel wire shall be delivered with tempered martensitic structure. Microstructure uniformity is an important index to determine the properties of oil quenched and tempered steel wire. Due to the limited hardenability of carbon spring steel wire, the core of too large steel wire can not be completely transformed into martensite after quenching and tempering. Therefore, the standard stipulates that the supply diameter of oil quenched tempered carbon spring steel wire is less than 12.0 mm.
Compared with cold drawn carbon spring steel wire, the tensile strength and elastic limit of oil quenched tempered steel wire with diameter ≤ 2.0 mm are lower than that of cold drawn steel wire. However, it is impossible to obtain high tensile strength by drawing with large reduction ratio after sorbite treatment of large size steel wire (Φ≥ 6.0 mm). However, as long as oil quenched and tempered steel wire is completely quenched, it can obtain higher tensile strength than cold drawn steel wire. Even under the same tensile strength, the elastic limit of oil quenched tempered steel wire is higher than that of cold drawn steel wire.
The anisotropy of cold drawn spring steel wire is obvious, while that of oil quenched and tempered steel wire is almost the same. The fatigue life and stress relaxation resistance of oil quenched and tempered steel wire are much better than that of cold drawn steel wire, the working temperature is higher (150 ~ 170 ℃), and the creep resistance is better. In addition, oil quenched and tempered steel wire has good straightness, and the steel wire is elastic and straight after opening coil, and has better formability when winding spring. Therefore, large size oil quenched and tempered carbon spring steel wire almost replaced cold drawn carbon spring steel wire in developed countries.
(6) Yb / t5102-93 oil quenched tempered carbon spring steel wire for valves
The relationship between Yb / t5102-93 and Yb / t5103-93 is equivalent to that of GB / t4358-1995 and GB / t4357-89. The former is used to make dynamic spring, and the latter is a general standard, which is mainly used to make static spring. Because the dynamic oil quenching and tempering spring has more strict requirements on the structure uniformity and the hardenability of carbon steel is limited, Yb / t5102 has smaller supply specification (diameter ≤ 6.0 mm).
The service range and quality control requirements of oil quenched and tempered carbon steel wire for valves are basically equivalent to group G of GB / t4358-1995, which will not be repeated here.