Study On Composition Optimization Of230-400Cast Steel

The fast and continuous development of the national economy drives thedevelopment of the railway transport. The renewal of the freight car alsobecomes inevitable. As the key part of the railway freight car, it becomesparticularly important that how to make the steel of bogie meet its usingperformance and good stability. Nowdays, in production technical requirementsof the steel of the using freight car, it is only the request of the maximum forchemical composition.Because of the wide range of the request, the performanceof the bogie steel is very different, which producted to the extent. This is not onlyno specific reference standard in production, but also the advantageous to thepractical application of service life and the location of other parameters.Therefore, we need to study the using steel of the freight car, and find out thebest composition for the accurate quantitative standards of the future production.This article studies the influence law of structure and properties of cast steelbecause of the content changes of the alloy element carbon, silicon, manganese,nickel, chrome, through the control variable method. In the condition of meetingthe mechanical properties, we will find out the most reasonable chemicalcompositions.Research shows that: When the content of carbon ranges from0.15%to0.24%, with the increasing of the content of carbon, pearlite gradually increase,hardness, tensile strength and the yield strength increase, but elongation andimpact energy gradually reduce; When the content of silicon ranges from0.1%to0.4%, with the increasing of the content of silicon, the distribution of themicrostructure is more and more uniformed, the size of the microstructure isbigger and bigger, hardness, tensile strength gradually increase, impact value andthe yield strength first increase, then decrease, but the extension first decreasethen, increase; When the content of manganese ranges from0.3%to0.9%, with the increasing of the content of manganese,the content of the pearlite is increase,the microstructure is smaller and smaller, the size and distribution of themicrostructure are more and more uniformed, hardness, tensile strength, yieldstrength gradually increase, while the extension first decrease, then increase, theimpact value gradually decrease; When the content of nickel ranges from0to0.3%, with the increasing of the content of nickel, pearlite reduces, grain size issmaller and smaller, the size and distribution are more and more uniformed, andthe widmanstatten is appeared in the microstructure, tensile strength graduallyincrease, while the hardness, yield strength and elongation rate graduallydecrease, impact value first increases, then decreases; When the chromium ofcarbon ranges from0to0.18%, with the increasing of the content of chromium,the microstructure is smaller and smaller, the distribution is more and moreuniformed, tensile strength, yield strength gradually increase, hardness graduallyreduce, impact value and elongation first increase, then decrease. According tothe requirements of the production and the rule of the changing alloy elements,the stable component composition is: the content of carbon is from0.18%to0.2%, the content of silicon is from0.2%to0.3%, the content of manganese isfrom0.3%to0.5%, the content of chromium is from0.06%to0.12%.