The production flowsheet of Φ 16mm product of spring steel 60Si2CrVAT (/% : 0. 58C

1.76Si

0. 66Mn

0. 010P

0. 005S

1. 15Cr

0. 15V) is BOF-LF-VD-22Q mm x300 mm bloom casting-rolling-annealing process. The main manufacturing process of spring for railway freight train is punching machine unloading-medium frequency induction heating- hot coiling spring-residual heat quenching ( 890 ~ 870 °C

oil cooling) -530 °C tempering in electric resistance furnace-grinding-shot blasting-pre-compression process. The cause of fracture of Φ16 mm K6 spring with 620 000 times in fatigue test (standard requirement ≥3 000 000 times) is analyzed. Results show that the hurt at point-contact between spring supporting ring and effective ring led to stress concentration is main cause of earlier fatigue fracture

while the abnormal lower bainite existing at local region of spring is disadvantage for spring fatigue life. With improving spring manufacturing process including insuring supporting ring size and controlling spring quenching temperature

preventing local point contact at spring fatigue test

the test fatigue life of spring of steel 60Si2CrVAT is up to ≥3 000 000 times.