What is Titanium? (Ti)
Titanium is a lustrous, silver-gray, metallic element. It has the strength of steel and yet weight comparable to aluminum. It responds very little to electricity, heat and magnets (making it perfect as the medium for a magnetic bracelet). In addition, titanium forms protective surface layers, which gives it excellent resistance to corrosive attacks by saltwater, sea air and certain acids. It is even capable of being submerged in water for long periods of time without sustaining damage.
Where is it being used?
Blackbird Titanium is one of the favorite metals in the aerospace industry. After World War II, the U.S. military was developing advanced missile systems and aircraft that could fly faster than the speed of sound. It needed a stronger metal, one that could handle the high temperature and the NASA stresses produced by air friction when traveling at high speed. It chose titanium. The Black Bird (AKA Habu) is made of titanium alloy. It can fly more than 2,200 mph (more than three times the speed of sound). NASA has also realized the benefits of titanium, using it to make many of its space shuttles.
Most of the grades are of alloyed type with various additions of for example aluminum, vanadium, nickel, ruthenium, molybdenum, chromium or zirconium for the purpose of improving and/or combining various mechanical characteristics, heat resistance, conductivity, microstructure, creep, ductility, corrosion resistance etc. etc.
Palladium (Pd) and ruthenium (Ru), Nickel (Ni) and molybdenum (Mo) are elements which can be added to the pure titanium types in order to obtain a significant improvement of corrosion resistance particularly in slightly reducing environments where titanium otherwise might face some problems due to insufficient conditions for formation of the necessary protective oxide film on the metal surface. The formation of a stable and substantially inert protective oxide film on the surface is otherwise the secret behind the extraordinary corrosion resistance of titanium .
The mechanical properties of commercially pure titanium are in fact controlled by "alloying" to various levels of oxygen and nitrogen to obtain strength levels varying between approximately 290 and 550 MPa. For higher strength levels alloying elements, e.g. Al and V have to be added. Ti3Al2,5V has a tensile strength of minimum 620MPa in annealed condition and minimum 860 MPa in the as cold worked and stress relieved condition. The CP-titanium grades are nominally all alpha in structure, whereas many of the titanium alloys have a two phase alpha + beta structure. There are also titanium alloys with high alloying additions having an entire beta phase structure. While alpha alloys cannot be heat treated to increase strength, the addition of 2,5% copper would result in a material which responds to solution treatment and ageing in a similar way to aluminum-copper.
|
