Titanium, as an engineering material, has been developed in the past 50 years. This may seem like a long time, but in fact, as an engineering material, this time is relatively short. It takes many years to build a credible database. The credibility of data in the database is based on controllable research confirmed by application experience.

The most attractive feature of titanium is its extremely high strength-mass ratio. Their mass is only 57% of the same volume steel, but their strength is comparable to that of heat treated iron-carbon alloys. Titanium is an ideal material for aerospace, jet aircraft and missiles. But its biggest disadvantage is that the cost is too high. Titanium is not encouraged as a fastener unless there is no alternative.

Titanium alloys exhibit excellent corrosion resistance in harsh environments, which is the main reason why they are used in chemical equipment manufacturing. It has good high and low temperature characteristics, non-magnetization and low thermal conductivity and thermal expansion coefficient.

On the negative side, it is very difficult to process titanium fasteners. And when the thread fastener is installed and locked, the thread is easily scratched or stuck. Here are some examples of stress corrosion sensitivity of titanium alloys at appropriate high temperatures. But this situation can be mitigated by some special processes.

titanium alloy

Pure titanium is not heat-treated. Generally speaking, almost no fasteners are made of pure titanium.

There are many titanium alloys, most of which are exclusive. The results show that only a small proportion of planed titanium alloys are suitable for manufacturing threaded fasteners.

Ti-6Al-4V is a heavy-duty alloy. The fastener made of this alloy has a minimum tensile strength of 135,000 psi, with high strength and satisfying toughness.

Ti-6Al-4Mn has great creep resistance and is easy to cast. Its strength characteristics are similar to those of Ti-6Al-4V alloy, but its toughness is slightly worse.

The tensile strength of Ti-1Al-8V-5Fe is about 200,000 psi. It should be exaggerated that its outstanding strength-mass ratio is equal to that of steel fasteners with 350,000 psi tensile strength.

Two other titanium alloys, Ti-6Al-12Zr and Ti-6Al-6V-2Sn, are sometimes used in fastener manufacturing.

strength characteristics

The mechanical properties of titanium alloy external thread fasteners are guided by ASTM F468 on page B-158 and ASTM F467 on page B-184. In these specifications, the identification number of Ti-6Al-4V alloy is 5.