Progress in the production and processing of creep resistant titanium alloys

Resistance to loads at high temperature is one of the main limiting factors in improving the efficiency of jet engines. Titanium alloys are inferior to nickel alloys at absolute temperatures and strengths, but exceed them in terms of specific characteristics with respect to density. Near-a titanium alloys have a maximum complex of high-temperature characteristics, due to high creep resistance of hexagonal a-phase. The main way for increasing the strength is a solid-solution hardening, primarily by the α-stabilizers Zr, Sn, Si. Strengthening by the beta stabilizers Mo, V, Nb, W, Mn is limited mainly by the limits of solubility in the a-phase. Their excess amount leads to the stabilization of the β phase, which substantially reduces the creep resistance. Beta stabilizers Ni, Fe, dramatically reduce the creep resistance, even in small amounts, equal to the impurity content in the titanium sponge.

The method of titanium sponge production with an extremely low content of Ni≤0.0015%wt. and Cr≤0.001% wt. was developed. The work shows a significant increase of the creep properties Ti6242 and BT18U alloys melted on low Ni,Cr sponge. Profit in possible operation properties is shown.

The influence of rare-earth elements alloying on the example of Gd on the heat resistance and mechanical properties of the alloy VT18U is also considered.

The results of the effect of optimization of the chemical composition on a complex of mechanical properties VT18U are given.