Titanium alloys at low and ultra-low temperature

Titanium alloys at low and ultra-low temperature, retains its mechanical properties. Low temperature performance, low interstitial elements of titanium, as TA7, at -253 ℃ still maintain a certain plasticity. Thus, low-temperature titanium alloy is also an important structural materials.
Large chemical activity
Chemical activity of titanium cap screws is large, a strong chemical reaction with atmospheric O, N, H, CO, CO2, water vapor, ammonia and the like. Carbon content greater than 0.2%, it will form a hard TiC in the titanium alloy; at higher temperatures, and also the role of N forms TiN hard surface; at above 600 ℃, the high hardness of hardened layer is formed of titanium absorbs oxygen ; hydrogen content increased, brittle layer will form. Absorbing gas produced brittle surface to a depth of 0.1 ~ 0.15 mm, the degree of hardening of 20% to 30%. Chemical affinity of titanium is also large, easy and sticking friction surface.
Small thermal elasticity
Thermal conductivity of titanium λ = 15.24W / (mK) approximately 1/4 of nickel, iron 1/5, 1/14 aluminum, while the thermal conductivity of various titanium alloys decreased by 50% than the thermal conductivity of copper nickel square bar. Elastic modulus was about 1/2 of the titanium alloy for steel, so the poor rigidity, deformation, and should not be made thin-walled elongated rod member, the machined surface when cutting a large amount of spring back, the stainless steel is about 2 to 3 times, causing severe tool flank friction, adhesion, adhesive wear.