Numerical calculation and experimental evaluation of counter-gravity investment casting of Ti-48Al-2Cr-2Nb alloy

In this work, counter-gravity investment casting was used to fabricate TiAl parts with different cross-sections. A three-dimensional finite element model of counter-gravity investment casting was established based on ProCAST simulation software. The filling capacity and solidification behaviour during the counter-gravity investment casting of the Ti-48Al-2Cr-2Nb alloy were numerically investigated, and the effects of filling pressure, melt superheating temperature and mould preheating temperature were experimentally evaluated in terms of the filling integrity and casting defects. The results show that the filling pressure plays an important role in the filling capacity. Elevating properly the mould preheating and melt superheating temperatures can also improve the filling capacity. Then, counter-gravity investment casting was performed using the parameters optimised through numerical simulations, and sound Ti-48Al-2Cr-2Nb casting parts with different section sizes and shapes were produced. The as-cast microstructure of the Ti-48Al-2Cr-2Nb alloy indicates that the phase composition and morphology are largely affected by the size effect. [Figure not available: see fulltext.].