Elimination of misrun and gas hole defects of investment casting TiAl alloy turbocharger based on numerical simulation and experimental study

摘要

Casting technology of thin-wall TiAl alloy turbochargers was studied by investment casting andnumerical simulation. Misruns and gas holes were the main defects observed in preliminary work due to the poorfluidity of alloy, and to gas entrapment. In order to eliminate these defects, cast parameters, such as centrifugalrotation rate and mould preheating temperature, were optimized by numerical simulation, meanwhile, thestructure of the shell mould was optimized to improve the filling capacity of TiAl alloy. Pouring experiments werecarried out by vacuum induction melting furnace equipped with a water-cooled copper crucible based on theabove optimization. The quality of the TiAl alloy casting was analyzed by fluorescent penetrant inspection andX-ray detection. The results show that a centrifugal rotation rate of 200 rpm, mould preheating temperature of600 °C, shell preparation through organic fiber addition can dramatically improve the mould filling capacity, andintegrated turbochargers were finally prepared.