Alloys are metallic materials that have been blended with other metals or materials to enhance or suppress specific characteristics. This may be for purposes of hardening, corrosion resistance, malleability, temperature tolerance, or to facilitate other manufacturing capabilities, such as extrusion or die casting.
Alloyed metals are used to make pipe, machine stock, high strength structural components for buildings and equipment, functional and aesthetic architectural elements, jewelry, appliances, tools, electronics, and coins.
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The History of Alloys
Ironware from as far back as 1800 B.C. has been found. It is safe to assume that the manufacture of alloyed metals came long before the use of metals in purified form, due to the lack of pure metals or the ability to refine them. The Roman military used weapons and armor that were forged from the less-than-pure metals available at the time.
In the sixteenth century B.C., in southern India and Sri Lanka, the monsoon winds were harnessed seasonally to make steel in wind furnaces. The Persians discovered carbon steel, initiating the "Iron Age" with agricultural tools and weapons of war.
Coins of "electrum" (half gold and half silver) and items made from 18k yellow gold were found in King Tutankhamen's tomb, dating back to 1300 B.C.
Bronze was developed in the third century B.C., by the Sumerians. It was the first intentional creation of an alloyed metal and was used to make musical instruments, weapons and farm implements, depending on which mine the metals came from, as different locations offered varying quantities of inclusion metals.
The Chinese made quench hardened steel as early as 400 B.C. and during the Han Dynasty, around 200 A.D. intermediate carbon steel was developed.
By 20 B.C., the Romans had created a "gold substitute" which was 75% copper and 25% zinc. Later known as brass, Caesar Augustus had coins made from the alloy, and stamped with his likeness.
In 1869, the Periodic Table Of Elements was published. Metallurgists, alchemists, and industrialists could isolate metals by property, and the science of refinement was born.
The industrial age dawned at the turn of the 20th century. Metal alloys were put to the test in any number of ways, from creating ever stronger materials for ever more intricate mechanical functions, to lighter materials that facilitated space travel.
North American and Western European countries were primary producers and consumers in the global metal market until the early 2000s, when demand shifted to emerging Eastern markets. From 2002 through 2014, China experienced an industrial boom and became the world’s largest consumer of metal. Sudden drops in Chinese stock prices and currency devaluation caused sharp drops in metal prices in 2015.
Where Alloys are Used
Alloys are used in various industries: water extraction, treatment and distribution, construction, agriculture, architecture, packaging and shipping, automotive, medical, marine, aerospace, military, pharmaceuticals, consumer products and manufacturing industries including oil, petroleum and chemicals. Specific applications within these industries include gas turbines, electric motors, vessels, tubing, industrial tools and machine parts such as gears, flat wear, dental tools, medical devices, power transmission parts, gear boxes, missile pieces and various parts of marine vessels. Which metal alloy is used in which industry for which application, depends on the aspects of the alloy that are most necessary. In most of the applications in which alloy metals are used, there are no acceptable or economic alternatives to alloys. Some alloys are unique enough to be used in super specialized situations, such as those with particular nuclear absorption qualities, which are used in nuclear reactors. There are also alloys used as superconductors in very low temperature applications, and there those that are designed to resist the corrosive effects of boiling salt water and are used in desalination plants. Spacecraft building material is another specialized field that requires the use of metal alloys.
Suppliers and Customizing Alloys
Alloy suppliers offer stronger, more durable metals with more desirable properties than those of their individual components, such as increased hardness or malleability. Metals like aluminum, copper, magnesium, steel and nonferrous metals are common metal alloys that have increased material properties that make them more attractive on the market. On the other hand, the alloy's engineering properties such as tensile and shear strength, can be very different from the original materials, which were more heat resistant and not so brittle under those circumstances. In these cases, lightweight alloys with strong heat-resistance are created, known as high temperature alloys. High temperature alloys are metals that are composed of two or more metallic elements and have the capacity to operate or be utilized at extremely high temperatures such as 2000ºF (1093 C). Superalloys are also high temperature resistant, but with increased mechanical strength, good surface stability and both corrosion and oxidation resistance. Most metals can be used in the forming of alloys and there are therefore many of them, including stainless steel, pewter, brass, bronze and then the specialized custom alloys. Custom alloys are chemically altered to various degrees for specific applications. Alloys can also be categorized by the types of processes that they are utilized within, such as brazing alloys and welding alloys.
Alloy Fusion and Formulation
Specific alloys, mixed in specific proportions, create metallic components with specifically desired qualities. They may be ferrous metal (containing iron) or non-ferrous metal (containing no iron), electrically conductive, magnetic, thermally resistant, or non corrosive.
Architectural metals, for instance, include brass, bronze, copper alloys, or nickel alloys are used to manufacture doors, elevator components, handrails, grillwork, stairs, and builder's hardware, including hinges, handles, and knobs.
The compositions of these alloys are similar, but changing the base formula causes variations that may be significant to their appearance or function. Machinability is affected by the addition of elements. Machinability is the ease with which a metal can be cut, effectively removing material while leaving behind a satisfactory finish. The effectiveness refers to energy consumption, tool wear, and cost.
Architectural Bronze Formulation
Architectural bronze, with a rich, golden yellow color, has a good machinability rating, making it easy to extrude, cut, punch, or perforate. The metal composition of this alloy is as follows:
Copper = 55-59%
Lead = 2.5-3.5%
Zinc = balance
By adding a slightly higher percentage of copper and a slightly lower percentage of lead, the alloy retains its bronze hue, matching the architectural bronze, but provides a product that is better suited for bending.
By raising the percentages of both copper and lead, bright yellow brass is produced. The addition of tin creates naval brass, which is corrosion resistant in salt water, and retains a good level of machinability.
Nickel Silver Alloy
Nickel silver alloy is a silvery yellow when it is polished. It has high tensile strength and corrosion resistance, but is difficult to extrude. Its metallic composition is as follows:
Copper = 42-45%
Nickel = 9-11%
Zinc = balance
By adding 1% lead and 2% manganese to the nickel silver alloy, it becomes a deep chocolate brown color that retains all the qualities of the original formula.
Steel is an alloy of iron and carbon used in every nook and cranny of industry. Iron, rarely found in its pure form, is soft and ductile. The addition of up to 2.14% of carbon, by weight, stabilizes and hardens the iron, creating steel. Allotropic bonding of the elemental alloys takes place when the components are heated to specified temperatures. This bond may be body centered cubic (BCC) or face centered cubic (FCC) depending on the crystalline structure of the iron.
Varying the amount of carbon or adding other elements changes the molecular structure and physical properties of the steel. Some classes of alloy steel include carbon steel, tool steel, stainless steel, and aircraft alloys. These classes are rated by the American Iron and Steel Institute (AISI) on the basis of their machinability.
Stainless Steel Alloy
Stainless steel is a virtually oxidizing alloy with a minimum 11% chromium, making it highly corrosion resistant. The higher the chromium content, the more resistant it becomes. Up to 30% nickel or molybdenum may be added to increase resistance to pitting. Stainless steel is a low conductor of electricity, and is magnetic until it is annealed.
Stainless steel is resistant to bacterial growth and may be steam cleaned, so is used extensively in food and medical industries. It can be formed into sheets, rolls, bars, plates or wires. It is used architecturally for structural, as well as aesthetic purposes. Tanks for storage or transport of food or corrosive liquids are made of stainless steel, as are many components for production equipment, such as conveyor parts and packaging plant machinery.
Tool Steel Formulation
Tool steel falls under one of six main grades.
- Water hardening steels (W grades) are low cost, high carbon steel that are not resistant to high temperatures. They must be water quenched, making it too brittle for most tools. The addition of tungsten or cobalt improves its temperature resistance. The addition of nickel will increase strength and malleability.
- Air hardening steels (A grades) are "all purpose" steels. The addition of chromium to the alloy offers a low distortion, wear resistant product with good machinability. It is ideal for woodworking tools, gages, and cold forming.
- D Type (D grades) contain higher ratios of chromium to increase abrasion resistance and characteristics of air hardened steel. It is used for making forging dies, die blocks, and drawing dies for extruders.
- Oil hardening (O grades) are "all-purpose" tool steels. They are tough and abrasion resistant, making them a good general use product for manufacturing tools for standardized uses, such as hammers, blades, collets, and arbors.
- Shock resisting types (S grades) have relatively low carbon content. They are used for high impacting products such as jack hammer bits, chipper knives, and chisels.
- Hot-working (H grades) are low carbon, high temperature alloy steels that are resistant to corrosion and cracking during prolonged exposure to elevated temperatures. They metal alloys may include zinc, aluminum, or magnesium to add hardness and thermal resistance.
Aluminum alloys may be mixed with magnesium, manganese, iron, silicone, zinc, or copper, in quantities up to 15% by weight. The alloy material is added to the aluminum in liquid form. Aluminum alloys are designated by a four digit classification. The first digit being the main alloying element.
- 1xxx series aluminum contains 99% pure aluminum. It is corrosion resistant and has high thermal and electrical conductivity.
- 2xxx series are aluminum copper alloys. Often used in aircraft manufacturing, the soft metal is typically coated with a 6xxx layer to increase corrosion.
- 6xxx series aluminum contains magnesium and silicon. This is used for extruded aluminum products, vehicle parts, marine structures, and architectural components.
- 7xxx series are aluminum/ zinc alloys with a small quantity of magnesium to make aircraft aluminum.
- Series 2xxx, 6xxx, and 7xxx are heat treatable, meaning that their strength and resistance are increased by heating to specified temperatures, where the alloy elements melt into the aluminum base. The metal is then cold quenched, or rapidly cooled, "freezing" the molecular structure into place.
- Series 3XXX, 4xxx, and 5xxx are non heat treatable aluminum alloys.
Tungsten alloys have been developed for use in light bulb filaments, radiation shielding, TIG welding, and X-ray tubes. Because of the high density, tungsten alloys have been used to manufacture penetrating projectiles.
Tungsten carbide has a very high melting point and hardness level. It is used to make carbide cutting tools, such as saw blades, knives, turning, and milling tools used in woodworking, mining, metal working, and construction.
Gold is a very soft base metal. It is measured by purity and weight, in units called carats (k). Pure gold is 24k. Alloys are added to strengthen the gold. The quantity of carats refers to the ratio of pure gold to alloy. 18k gold has 6 parts of alloy. 14k gold has 10 parts of alloy. 10k gold has 14 parts of alloy.
The specific elements in the alloy ratio give the gold its strength and color. The alloys in yellow gold are one half copper and one half silver. Rose gold alloys contain three fourths copper and one fourth silver. Green gold alloys contain one fourth copper and three fourths silver. White gold alloys contain approximately one fifth copper, one fifth zinc, and three fifths nickel.
Alloy suppliers are companies that provide metals composed of two or more metallic elements.
Binary alloys are made up of two components.
Brazing alloys refer to various metal alloys that are used as filler metal in brazing processes, and differentiate based upon either the intended use or the method of application.
Casting alloys are alloys used to form objects in molds, and they are more easily molded than other alloys.
Intermetallics are alloys of two or more metals in a certain proportion, forming a new chemical compound.
Magnesium alloys are mixtures of magnesium and other metals
Metal alloys are amalgamations of two or more elements, one of which must be a metal.
Nickel alloy is a metallic material predominantly composed of nickel.
Quaternary alloys are alloys made up of four different components.
Steel alloys are most commonly made up of nickel, chromium, silicon, manganese, tungsten, molybdenum and vanadium, and are used for their increased hardness, strength and chemical resistance.
Superalloys, or high-performance alloys, can withstand extreme temperatures that would destroy metals like steel and aluminum. A superalloy will have excellent mechanical strength, surface stability and corrosion resistance.
Ternary alloys are alloys made up of three different components.
Titanium alloy is a metal alloy in which titanium remains the main component.
Welding alloys are metals that are formed from two or more metallic elements that are utilized during the welding process in order to function as a filler metal.
The direct impact of metal markets is through the actual number of jobs that are created by production, processing, fabrication, and wholesaling of the metal.
The indirect impact includes money exchanged for rent or purchase of facilities, utilities, and transportation costs involved in metal processes.
Factors that drive the prices of metal start with supply. Buyers are seeking the highest quality product possible for the lowest price. Sometimes metals can be mined and processed very inexpensively in one location, where conditions elsewhere make it cost prohibitive. This may be due to ease of obtaining and processing raw materials or labor costs. The primary cost of production is transportation. This drives metal prices down, moves jobs from an advanced economy to an emerging one, and changes local economic dynamics in both locations.
Fair trade agreements and tariffs charged on imports and exports are designed to offset the imbalance, ensuring workers receive a fair wage and treatment while consumers get a satisfactory product at a reasonable price.
Alloy Standards and Specifications
ASTM International, formerly American Society for Testing and Materials, has set standards for the manufacture and use of alloyed metals. These standards define the machinability, capabilities, and characteristics of each blend of alloy metals, and to what uses each may be applied.
It is important to find conscientious alloy suppliers when seeking products and materials, whether you need alloy bar stock for extrusion or die forming, piping, tubing, or flat plates.
Previous examples have shown how important the right metallic ratios can be and how easily they may be altered. Alloys that are manufactured correctly and ethically should be offered. The right metal supplier will know which alloys are best for a given purpose and provide a quality product to that end.
- A substance that has metallic properties and is composed of two or more elements, at least one of which is a metal.
- Alloying element
- An element added to a metal that affects changes in structure and properties.
- Alloy suppliers
- Are companies that provide metals composed of two or more metallic elements.
- Ion implantation
- A process using beams of ions of carbon, nitrogen and other elements which are fired into metals in a vacuum chamber in order to produce a thin layer of alloy on the metal surface.
- A process used to change the shape or form of metals and alloys.
- The study of the physical and chemical behavior of metallic elements, their intermetallic compounds and their alloy mixtures.
- Powder metallurgy
- The process by which alloys are mixed in powder form and heated into a solid, homogeneous alloy.