Physical

A metallic element, titanium is recognized for its high strength-to-weight ratio. It is a light, strong metal with low density that, when pure, is quite ductile (especially in an oxygen-free environment), lustrous, and metallic-white in color. The relatively high melting point (over 1,649 °C or 3,000 °F) makes it useful as a refractory metal. 

Commercial (99.2% pure) grades of titanium have ultimate tensile strengths of about 63,000 psi, equal to that of steels alloys, but are 45% lighter. Titanium is 60% heavier than aluminium, but more than twice as strong as the most commonly used 6061-T6 aluminium alloy. Certain titanium alloys (e.g., Beta C) achieve tensile strengths of over 200,000 psi (1.4 GPa). However, titanium loses strength when heated above 430 °C (800 °F)

It is fairly hard (although by no means as hard as some grades of heat-treated steel) and can be tricky to machine due to the fact that it will gall if sharp tools and proper cooling methods are not used. Like those made from steel, titanium structures have a fatigue limit which guarantees longevity in some applications. 

The metal is a dimorphic allotrope with the hexagonal alpha form changing into the body-centered cubic (lattice) beta form at 882 °C (1,619 °F). The heat capacity of the alpha form increases dramatically as it is heated to this transition temperature but then falls and remains fairly constant for the beta form regardless of temperature. 

Chemistry Data

The most noted chemical property of titanium is its excellent resistance to corrosion; it is almost as resistant as platinum, capable of withstanding attack by acids, moist chlorine gas, and by common salt solutions. Pure titanium is not soluble in water but is soluble in concentrated acids.

This metal forms a passive and protective oxide coating (leading to increased corrosion-resistance) when exposed to elevated temperatures in air, but at room temperatures it resists tarnishing. When it first forms, this protective layer is only 1 to 2 nanometers thick but continues to slowly grow; reaching a thickness of 25 nanometers in four years. 

Titanium burns when heated in air 610 °C (1,130 °F) or higher, forming titanium dioxide. It is also one of the few elements that burns in pure nitrogen gas (it burns at 800 °C or 1,472 °F and forms titanium nitride, which causes embrittlement). Titanium is resistant to dilute sulfuric and hydrochloric acid, along with chlorine gas, chloride solutions, and most organic acids. It is paramagnetic (weakly attracted to magnets) and has fairly low electrical and thermal conductivity.

Experiments have shown that natural titanium becomes radioactive after it is bombarded with deuterons, emitting mainly positrons and hard gamma rays. When it is red hot the metal combines with oxygen, and when it reaches 550 °C (1,022 °F) it combines with chlorine. It also reacts with the other halogens and absorbs hydrogen. 

Titanium is used in steel as an alloying element (ferro-titanium) to reduce grain size and as a deoxidizer, and in stainless steel to reduce carbon content. Titanium is often alloyed with aluminium (to refine grain size), vanadium, copper (to harden), iron, manganese, molybdenum, and with other metals. Applications for titanium mill products (sheet, plate, bar, wire, forgings, castings) can be found in industrial, aerospace, recreational and emerging markets.