Design Of Optimized Steel Used On Brake Disc And Evaluation Of Its Thermal Fatigue Lives

As one of the important accessories on oil machines, because of the heat effect and mechanical force, the surface of the brake disc? became invalidated by the way of appearing chap and abrasion in the using process.In this thesis, based on the cast steel (ZGSSCrMo) which was used before, the mechanism of failure and the effect of alloy elements on its properties were analyzed, and the composition of the former cast steel was changed by the way of adding proper quantity of rare earth element, reducing the amount of carbon (C) element, increasing the capacity of molybdenum (Mo) element, and appending a little copper (Cu) element. The test result showed that, under the condition of retaining its thermal plastic property, the strength of the optimized steel (ZGSSCrMoRE) can be increased evidently at high temperature. That is to say, the new steel was favorable of integrated thermal mechanical property.In order to study the operating mode and the failure effect factors of brake disc, the distribution character of its temperature field, thermal stress and strain field was analyzed by the finite element method. The result showed that the mechanical properties of brake disc affect its thermal stress and strainfield distribution directly. In addition, under using process, the speed of drillIIAbstractcan't be too high, and the time of brake can't be too short. So the braking prescription should be performed strictly, furthermore, the sudden and urgent braking should be avoided to the best of our abilities.In the end, the thermal fatigue lives were evaluated by the finite element method. It was proved that the thermal fatigue life of improved steel (ZG35CrMoRE) was higher than that of the formers'. It was also found that the quantitative evaluations of the thermal fatigue lives of brake disc were acquirable, by putting the equivalent plastic strain, which was analyzed with finite element methods, and the material mechanical property parameters into the formula of Manson-Coffon to calculate its lives. Therefore, theoretical method can be provided to develop new brake disc steel and to prolong its lives.