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Titanium heat treating is the industrial process of applying extremely high temperatures to titanium so that the metal becomes more workable for manufacturing purposes. The two most common types used today are annealing and stress relieving. Annealing serves mainly to make the titanium resist fracture while increasing its ductility, or ability to be stretched into thin wire. The stress relieving method, on the other hand, is used mostly to reduce the amount of stress the titanium undergoes while being welded or formed.
Either annealing or stress relieving is typically required to make titanium usable. Titanium that is not stress relieved may crack after being welded or formed, while that meant for extensive machine processing usually will not hold up to such heavy processing without first being annealed. Temperatures as high as 1,100°F (593°C) for stress relieving and 1,450°F (788°C) for annealing are not uncommon
Contamination is a crucial issue in titanium heat treating. Fabrication shops often have separate areas for titanium since this metal is especially prone to contamination from air, moisture, dust, and grease. Other high-performance metals, such as stainless steel and nickel-base alloys, do not require as strict attention to cleanliness as they are not as sensitive as titanium to contamination while being formed or welded.
It is important to note that pure elemental titanium is rarely used in modern manufacturing as it is a rather soft metal on its own. Titanium alloys, mixtures of titanium with other metals, allow for maximum hardening properties. Each particular titanium alloy will respond differently to the heat treatment process, however.
The National Aeronautics and Space Administration's (NASA) first Space Shuttle helped the public become more aware of the use of titanium alloys and titanium heat treating, as the shuttle used titanium heat shield insulation tiles to remain strong in high temperatures. Since the first space shuttle, NASA continued to incorporate titanium alloys in their designs because of their non-melting, strong properties. Manufacturers of quality swords and knives also rely on the strength of these alloys. They are even stronger for their weight than steel and are also resistant to corrosives such as acids, solvents, and bases.