Metallurgists have developed an impressive variety of useful metal alloys for manufacturing purposes. The combination of a metal and one or more other elements creates a metal alloy. Frequently, alloys combine a large quantity of a less expensive base metal, such as iron, with a more costly metal, such as gold or titanium.
About Titanium Alloys
Titanium occurs widely in nature in combination with other materials. In its purified form, titanium forms a metal. It displays two distinct possible crystallographic structures as a solid: an "alpha" hexagonal structure and a "beta" cubic structure. Metallurgists have identified three broad types of Titanium alloys based on the crystallographic form of the titanium used in the alloy. These metals differ somewhat in the physical properties they display.
Alpha and Near-Alpha Alloys: These alloys will generally weld well, but they are not heat treatable. They resist cold temperatures well, supply generally good ductility and offer low to medium levels of strength. Very high alpha or near-alpha alloys may resist oxidation.
Beta and Near-Beta Alloys: These readily heat treatable titanium alloys will also weld. They supply high strength within specified temperature ranges.
Combinations of Alpha and Beta Alloys: These alloys combine features of the other two types. Some display heat treatable properties and will weld. They offer medium to high levels of strength, but usually require hot (as opposed to cold) forming.
The Grades of Titanium Alloys
Both a private voluntary industry association called the American Society for Testing Materials (the "ASTM") and the American Society of Mechanical Engineers (the ASME") have issued guidelines for grading titanium. Many international companies have adopted these standards. Some 39 broad grades of titanium occur widely in the commercial marketplace; the grade number helps manufacturers identify the percentage composition of different alloys. For example, a "Grade 5" titanium alloy would include 6% aluminum and 4% vanadium.
Some manufacturers may also utilize other specifications. The Unified Numbering System (widely used in North America), the standards promulgated by the International Organization for Standardization (the ISO), and the EN Standards (used in the European Union) may address titanium alloys for specific purposes.
Properties And Applications
Although a few decades ago titanium alloys found utility mainly for military applications, today several other economic sectors also employ products containing these metals. Both the properties and applications of titanium alloys have helped create a high demand within some industries. However, price factors still limit the availability of some titanium alloy products:
Purified titanium forms a hard, lustrous silvery metal. Although it possesses impressive tensile strength, the element titanium displays considerably less density than steel (a cubic centimeter of titanium weighs only 4.5 grams). It also resists corrosion by salt water. Nonmagnetic and reportedly non-allergenic, titanium provides a low modulus of elasticity despite its high tensile strength. However, its high melting point of 3,038 degrees Fahrenheit for many years created challenges for manufacturers attempting to utilize Titanium as an alloy in commercial settings.
Today, titanium enjoys widespread use within the aerospace and aviation industries, as well as the defense industry. Its light weight and high strength within certain temperature ranges makes titanium well suited for a variety of aircraft parts. Additionally, titanium will resist corrosion from sea water better than many other materials, so alloys containing this metal have gained widespread use in power plant condensers and desalination plant facilities.
Although titanium products usually still command high prices, the metal titanium has found applications within the biomedical field for use in surgical and dental implants. Some luxury car makers reportedly employ titanium alloys in their vehicles, and consumers recently have begun using golf clubs, watches and jewelry with durable titanium alloy components. In the future, manufacturers will likely continue to discover new uses for titanium alloys.
Advantages of Titanium Alloys
Titanium alloys offer numerous advantages. First, they resist saltwater and chlorine corrosion well. Second, they offer lightweight strength within specified temperature ranges. Third, many titanium alloy products withstand cold temperatures. Fourth, these metals supply an attractive silvery surface finish. Finally, some titanium alloys retain shapes reliably.