12t级Ti80合金铸锭的成分均匀性及其偏析规律

Based on the simulation results by MeltFlow, the 1st 12 t ingot of Ti80 alloy was melted in China and then was verified by two times. The chemical testing results show that the composition difference of the upper, middle and bottom of the ingot is less than 1000 µg/g, and the composition difference of the 17 positions of the riser is less than 3000 µg/g. Both of them are equivalent to that of the 5 t ingot. Further, the macrosegregation at the riser was investigated and it is found that Al, Nb, Mo are enriched in the edge of the ingot and poor in the center of the ingot, whereas Zr has an opposite phenomenon. Microsegregation between the grain boundary and interior were studied by EDS. The results show that Nb and Mo are enriched within grains and poor at grain boundary. On the contrary, Al and Zr are enriched at grain boundary and poor within grains. The macro and micro segregation are consistent for Nb, Mo and Zr and opposite for Al. This is largely because the distribution of Nb, Mo and Zr is more depended on the solute redistribution at the solidification interface. By contrast, due to the high saturated vapor pressure at high temperature, Al is volatilized severely during the long time and high vacuum melting process and the solute redistribution is at the solidification interface.