The effect of deforming temperature 800 ~950 ℃ on structure and mechanical properties of steel 55SiCrA (% ： 0. 56C

1. 42Si

0. 68Cr) for auto suspension spring has been studied by Gleeble-1500 thermo/mechanical simulator and using optical

electron microscopy and mechanical property test. Results show that with increasing deforming temperature

the starting and finishing temperature of pearlite transformation gradually drop and the spacing of lamellar in pearlite decreases ； with defonning temperature 850 ~ 900℃

the spacing of lamellar in pearlite is 130 - 140 nm

and the steel has best comprehensive mechanical properties i. e. tensile strength 1 075 ~ 1 090 MPa with reduction of area 43. 5% 〜44. 0%.