Titanium and Ti-alloys are generally chosen for their mechanical properties, temperature resistance or chemical resistance. The specific points of special
interest for the spacecraft designer are considered here, since the basic aspects of titanium alloy assemblies are similar to those for aeronautic design.
Conventional Ti-alloys are used for primary and secondary structures; fasteners; in plumbing systems (standard tube alloy grades and commercially pure CP-grades) and in areas where operating temperatures preclude the use of aluminium alloys. "Memory alloys" based on titanium can find specialized uses as actuators.
Titanium alloys
are preferred for contact with CFRP due to their low CTE and matched galvanic corrosion properties.
The characteristics of titanium alloys are generally grouped according to their metallurgical structure which is, in turn, controlled by the chemical composition and heat-treatment history. Commercially pure (CP Ti) products are normally selected for chemical resistance. Impurities in CP Titanium can increase strength but with a loss in corrosion resistance.
Titanium alloys are
normally selected for their strength properties, which depend on a number of specific heat-treatments (age hardening, quench and temper). The most commonly used titanium alloy is Ti6Al4V for which extensive mechanical and corrosion property data are available. |
