| In order to solve the shrinkage defects of existing products,supported frame formed by investment casting,this paper applies Pro CAST casting simulation software to predict the generating of shrinkage casting defects.The shrinkage defects were solved with optimizing the feeding system design.The microstructure and mechanical properties of the casting produced by the optimizing feeding system were analysized.The solidification process simulation results show that the shrinkage defects occurred mainly in the outer large end surface,outer small flange end surface and inner boss parts.Defects in outer large flange almost integrally connected to each other along the annular and the quantity and volume of defects are far greater than those in outer small flange end surface.The shrinkage defects were found in every inner boss and the maximum probability reached more than 50%.The probability of shrinkage appearing in other portion is relatively small.According to the simulation and the actual production test results,this paper transforms the original feed system which sets outer large flange down and outer small flange upward into a new feed system design,which sets outer large flange upward and outer small flange down,connects the ingate with the outer large flange,and sets riser upon the boss.The optimizing feed system design significantly reduced the tendency of shrinkage defects in the outer large,small flange end and inner boss.Furthermore,the tendency overall shrinkage defects achieve minimum when mold shell's preheating temperature keeps about 900?.Analysis based on K4169 alloy casting microstructure,room temperature tensile and creep rupture properties after the optimizing feeding system reveals that its microstructure is stable.The room temperature tensile of casting is improved,the stability is obviously improved and lasting life overpasses 30 minutes.The properties achieve the design requirements. |
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