Numerical simulation and process optimization of precision casting for large complex thin-walled TiAl alloy compressor casing

Based on ProCAST numerical simulation software, the effects of centrifugal casting and gravity casting on the forming of Ti-48Al-2Nb-2Cr alloy diffuser casing are analysed comparatively. The results show that centrifugal pouring at rotational speed of 400 r/min enhances the directional mold filling of molten metal and forced convection during solidification. Compared with gravity pouring, it greatly shortens solidification time and reduces shrinkage porosity volume by 21.8%. A curved riser gating system is innovatively designed to address hot spots in thick-wall regions, transferring defects on the inner ring flange to the risers. This design cuts shrinkage porosity volume by 47.1% relative to the straight risers. Experimental verification confirms that castings fabricated with optimized processes have no internal defects detected by X-ray inspection and no shrinkage porosity observed under microstructure examination. Fine-grained structures with lamellar colonies of 400 μm form in thin-wall support plates due to rapid cooling. Its tensile strength at room temperature and 750 ℃ rises by 4.9% and 10%, respectively, comparing with thick-wall flanges. These findings provide a reliable process scheme for high-quality forming of large-scale complex thin-wall TiAl components.