Variation of stress relaxation of titanium alloys as a function of the conditions of deformation at high temperatures

Conclusions

• 1. Forging of the VT3-1 and VT14 alloys at temperatures of the β-region leads to the formation of large grains, a nonuniform, large-needle microstructure, low ductility (particularly the reduction in section), and low resistance to relaxation.

• 2. The decrease of the initial forging temperature to the temperature of the α+β region, other conditions being equal, leads to the formation of a more uniform equiaxial and small-grained structure and increases the ductility and the relaxation resistance.

• 3. An increase of the testing temperature of the VT3-1 alloy to 100°C has no effect on the resistance to stress relaxation during the 1000 h of testing; in the case of the VT14 alloy the relaxation resistance decreases.

  The resistance of the VT3-1 alloy to stress relaxation is higher than that of the VT14 alloy and of the 60Kh3G8N8V alloy used at the present time for banding.

• 4. The VT14 alloy is more susceptible to deformation at high temperatures than the VT3-1 alloy not only in terms of its mechanical characteristics but also in terms of resistance to stress relaxation.