Research Of 60Si2CrVAT Spring Steel Mechanical Porperties

Shelf spring of railway truck bears greater dynamic or impacting loading at work and it is one of the key parts which determines the train safe operation. With the constant speed-raising of the railway truck, the request for a spring mechanical properties is higher and higher. In order to guarantee its safe and reliable properties under the condition of raising speed and heavily loaded environment, the material need improve. The spring steel of 60Si2CrVAT is the main material of the railway speed-raising truck bogie spring in our country at present, because this material begins to use after the railway truck raising its speed in the near future, so there is less investigation about it. In order to excavate the potentiality of the material, the effect of heat treatment process on 60Si2CrVAT spring steel mechanical properties have been investigated detailedly and its fatigue life have been estimated according to P-S-N curve. The results have shown that: The tempering hardness of spring steel 60Si2CrVAT slowly decreased with increasing temperature below 300 degrees centigrade, However, the tempering hardness above 300 degrees centigrade increased in rapid speed with increasing the temperature. The tempering curve of remaining thermal quenching is higher than that of two times quenching. With the increase of the inducing heating speed, the tensile and yielding strength declined, however, the rate of yielding and strength, elongation rate and section shrinking rate hadn't too much change. The heating speed is a main factor of influencing 60Si2CrVAT spring steel mechanical properties. When the reliability is 50%, 90%, 95% and 99%, the tired limit of 60Si2CrVAT spring steel is 669.8MPa , 644.4MPa , 638.4MPa and 626.8MPa respectively; when curvature radius of breach is 0.75mm, average tired breach coefficient of 60Si2CrVAT spring steel is 1.56; Under the second disposing (860 oil quench , 520 tempering ) , the calculating value of 60Si2CrVAT steel fatigue life is 7,656,000 times and the measuring value is more than 3 million times (note: Test ends after 3 million times, no fatigue destroy at this moment).