The effect of 0.01%~0.22%V on relax resistance

mechanical properties and precipitated phase of Si- Mn   spring   steels(0.34~0.53C

1.06~1.24Si

1. 17~1.36Mn)with   870～900℃  normalizing

900~920   ℃  quenching and 400~460 ℃ tempering has been studied by Bauschinger test and transmission electron microscope examination.  Results showed that with increasing austenitizing temperature at 870~920 ℃

the strength of steel increased; with adding vanadium in steel the area of relax loop and relax resistance of steel increased; and the available vanadium content in steel  was 0.05%~0. 10% which had obvious precipitates of second phase in steel and the second phase particle in 0.06%V steel was fine.