Study On Mold Filling And Solidification Process Of Superalloy Castings With Mutations In Wall Sickness

This paper takes the wall-thickness varied castings of K4169under vacuumcounter gravity casting as the research object. This paper empl oys finite elementanalysis software ProCAST to investigate the process of mold filling andsolidification and the factors of influence sphere of wall sickness sudden-changedparts affecting castings. And then verify process parameters using similarexperiments. Finally, the article obtained the effects of geometric factors andprocessing parameters on the thin-wall casting.Under the condition of preheating shell temperature900℃, filling velocity16.8KPa/s and forming pressure150KPa, finite element analysis results forcastings with different wall sickness and wall-thickness variation turns out that inpace of wall thinning filling time becomes longer, solidification time becomesshorter, and temperature field becomes more uneven. In pace of increasing flowfield becomes more uneven, solidification time becomes longer, and when thethickness mutation rate is more than4, vortex generate in wall sickness mutationarea. With Wall thickening, the fluence sphere wall sickness mutation area affectingcastings becomes smaller. With wall mutation rate becoming larger, shrinkageaffected zone increases slightly and stress-affected zone first increases and thendecreases. And when the mutation rate is equal to6, stress-affected zone reaches amaximum. The simulation results show that when wall edges exist in mutatedregion, castings stress significantly increased, and when the thickness is small, theincrease is more larger.The filling velocity and temperature of the pre-heated shell have a more significant influence on the filling and solidification behavior of the casting with criticalwall-thickness. The wall-thickness, thickness variation rate and forming pressure have significant effects on the boss, and the filling velocity is critical in determining the quality of casting.The optimum filling velocity is related with wall-thicknss of the casting. As the wall-thickness changes from4mm to1mm, the optimum filling velocity increses from below100mm/s to200mm/s.The forming pressure is responsible for the fillingof the melt and maintaining the pressure during shrinkage. As the wall-thickness ch anges from4mm to1mm, the pressure required increses from50KPa to200KPa.