Deoxidation of Ti Powder and Preparation of Ti Ingot with Low Oxygen Concentration

In this experiment, we carried out a two-step deoxidation process to obtain Ti ingots with low oxygen concentration from commercial Ti powder. The first step was to primarily reduce oxygen in Ti powder using Ca and the second was to melt the deoxidized Ti powder in Ar atmosphere with added hydrogen using a vacuum arc melting system. We used two types of raw Ti powder, one with a high oxygen concentration of 5,600 ppm and average powder size of 35 mu m, and the other with 2,200 ppm and 115 mu m. The high oxygen of 5,600 ppm in the Ti powder was reduced to approximately 1,460 ppm by the two-step process of melting after deoxidizing the Ti powder with Ca at 973 K. On the other hand, in the case of the Ti powder with low oxygen of 2,200 ppm, the Ti ingot with low oxygen of 600 ppm could be prepared by the two-step process of melting after deoxidizing at 1,103 K. The Vickers hardness and c/a value of Ti ingots decreased as the oxygen concentration decreased. [doi:10.2320/matertrans.M2012004]