Research On Improving The Yield Strength And Grain Size Of LZ50 Steel After Heat Treatment

Axles are important parts of railway cars,which directly affect the vehicle's safety,is to run some of the most important parts.In order to adapt the "high speed and heavy load"railway development requirements,improve road safety,prevent the occurrence of truck cold cut axle,we must further improve the mechanical properties of axles,once the axle at work because of fatigue,bending,torsion or stress fracture,direct threats to the running safety of railway freight cars,caused significant direct and indirect economic losses.LZ50 steel with high strength,high toughness and high fatigue resistance,excellent properties,is widely used in railway vehicle axles.In order to improve the performance of axle,LZ50 steel axis composition unchanged in case,axle after forged heat treatment processes should be improved,so as to improve the mechanical properties of axles to ensure quality to meet the standard requirements of the axle,increased axle after heat treatment,the pass rate.This paper focuses on the two normalizing and heat treatment process for different parameters of the compare the microstructure and mechanical properties in order to determine the appropriate process.On the axle after forged cut in small pieces two fire test of a heat treatment process,determine the best hanging axle after heat treatment process experiment of heat treatment production line.And heat treatment production line for hanging axle temperature detecting and strengthening the improvement of the cooling capacity,the heat-treated axles extended mechanical properties and grain inspection,according to the test results form a sound after the final process,retaining the originals.Through developed rigorous of test programme,according to steps article-by-article operation,and accumulated data,be analysis summary,understand LZ50 axis of are fire,and tempered and the cooling way and mechanical performance of mutual relationship,and through axle heat treatment test,on heat treatment Hou of axle processing and prepared sample,and detection results,can integrated analysis obtained LZ50 steel axle heat treatment Hou yield strength and the grain degrees analysis results,integrated evaluation LZ50 steel axle mechanical performance and the grain degrees,And get 50 steel axle heat treatment effects of the yield strength and grain size of the main factors,acquire and optimize heat treatment process of LZ50 steel axis,improving the yield strength and grain size of LZ50 steel axle,increased axle production pass rate.