1992 Volume 32 Issue 5 Pages 664-672
Aiming at controlling the composition of refractory and reactive metals in electron beam melting, melting experiments were carried out for commercially pure titanium (C.P.Ti), Ti-6Al-4V alloy and pure niobium and the following results were obtained:
(1) In the melting of C.P.Ti, the addition of TiO2 powder as an oxygen source and independent control of the feeding rates of titanium sponge and TiO2 enabled the fine composition adjustment of [O]. The properties of the materials produced from the ingots obtained were the same as those of materials produced by the conventional VAR-forging process.
(2) In the melting of Ti-6Al-4V alloy, it was confirmed that the evaporation of Al could be rationally expressed by the Langmuir equation. Also, in the independent control of the feeding rates of titanium sponge and Al-V alloy, the control of molten pool temperature made the uniform composition adjustment of [Al] and [V] possible.
(3) In the melting of pure Nb, deoxidation and denitrification ratio were improved as melting energy increased, and these reactions were considered to be rate-controlled by degassing reactions. In addition, the relation between residual resistance ratio (RRR) and the contents of impurities was quantified.
