Diffusion welding of titanium using pressure at the initial stage

Abstract

As an example of alloy OT4 it is shown, that at diffusion welding of titanium alloys with the original globular (equiaxed fine-grained) microstructure, the accumulated strain value of the welded blanks can be reduced (more than 2 times) if the welding process is performed in the temperature range of polymorphic transformation (∼950 °С). In such a case, use the welding pressure only at the first stage to form a physical contact with an area of at least 50% of the nominal, and then produce an isothermal annealing without pressure, the duration of which is temperature dependent. When using a temperature higher than the end of polymorphic transformation (∼1000 °C), the duration of annealing is reduced by almost 10 times compared with annealing at 950 °C.

Keywords:

• Titanium alloys
• microstructure
• diffusion welding
• microrelief