Research On Technical Parameters Of Crossing Casting Of High Manganese Steel

As a significant part of a railway system,the crossing can directly reflect the level of the track line.The improvement of its casting performance has a profound impact on railway transport capacity.With the continuous development of high manganese steel crossing manufacturing technology,the monoblock casting crossing of high manganese steel is also moving towards the small crossing used for special lines and station lines.With the successful trial production of the monoblock casting crossing of high manganese steel in the early '60s,the yield of the crossing has increased gradually in the past decades,and the structure form and manufacturing technology have also made a comprehensive improvement and breakthrough.In 1997,With the increase of allowable speed of China's railway,high-speed and heavy-load railways entered a stage of rapid development.In just20 years,the standard EMU(Electric Multiple Units)"Fuxing" was launched,which realized the leap from "Universal Locomotive" to standard EMU.According to statistics,the crossing of high manganese steel in China accounts for more than 50%,while the crossing of North America,Russia,and other cold areas is all used high manganese steel because the train's constant increase in speed and load of its various parts put forward higher requirements.The high plastic toughness and high work hardening ability of high manganese steel undoubtedly make it a good material for crossing,but the casting defect is caused by its poor casting performance such as large solidification shrinkage rate and poor heat dissipation,which greatly shorten the service life of high manganese steel crossing.Therefore,as the first procedure of the crossing production of high manganese steel,reducing the defect and improving the quality of the casting becomes the top priority of improving the crossing production of high manganese steel.First,according to the frog defect of the high manganese steel crossing,the numerical simulation method to manifest the casting process is applied,the technological parameters of the crossing are optimized and the method to reduce the casting defects is studied in this paper.Since then,the geometric crossing model of monoblock casting,the casting mathematical model based on the implicit algorithm of ProCAST casting software,and the nonlinear thermal physical finite element model of high manganese steel are established,and the numerical simulation assumption of casting speed attenuation is put forward in view of the situation of metal liquid spilling over the riser during inclined casting.Secondly,to explore the relationship between casting defect formation and the cooling process,the crossing pouring process is manifested.the results show that the exothermic energy of 1 200 k J/kg of exothermic riser temperature field distribution is more uniform and defects to riser together the principle of directional solidification,shrinkage porosity proportion compared with thermal insulating riser reduced from23.10% to 17.01%,and the shrinkage cavity proportion from 1.002% down to 0.530%,but change the riser burning time had no significant effect for the monoblock casting crossing.Then,according to the relationship between casting defect formation and cooling process,the riser process optimization scheme was put forward,and the shrinkage defects such as porosity and cavity were predicted according to the "V" type feeding area of the exothermic riser.The local shrinkage porosity proportion decreases from 36.17% to22.11%,and the local shrinkage cavity proportion decreases from 1.13% to 0.69% because of this improvement.Finally,this paper uses the CAFE microstructure analysis module of ProCAST software to explore the macrostructure growth rule of crossing casting solidification and adjusts the Gaussian parameters by combining the thermal property of the material and the practical application.The comparison of the simulation results and the actual production has a high consistency.Therefore,to continue to analyze the theoretical feasibility of the crossing production method for a combination of forging and casting,the solidification and crystallization process is analyzed.