| Frequently Asked Questions |
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| What is magnesium? |
| Magnesium is the lightest of all the commonly used metals. It is one of the most abundant element in the earth's surface, amounting to about 2.5 percent of its composition. |
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| Where is magnesium found? |
| Magnesium is produced from sea water, brines and magnesium-bearing minerals, which offer unlimited reserves. |
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| How is magnesium used in the market? |
Most pure metals, including magnesium, are too soft for structural use. However strength properties comparable to those of many aluminum alloys are obtained by alloying magnesium with other metals, and, in some cases, by heat treating or working.
Magnesium is used as an alloy in other metals, most often aluminum. Magnesium melts at 650 degrees C (1202 degrees F), about the same temperature as required to melt aluminum. Aluminum represents 40 - 45 percent of total demand for magnesium.
Magnesium alloys, used in foundry work, represent approximately one-third of total worldwide demand for the metal.
Magnesium is also used in desulfurization with other metals, specifically steel. Sulfur has a deleterious effect on the properties of steel, and the increasing demands of the market have forced the steel industry to provide products with lower sulfur content. Magnesium has a high affinity for sulfur, and when injected into molten iron or steel, it will reduce the sulfur content dramatically. |
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| How is magnesium brought to market? |
| Magnesium alloys are processed into castings (die, sand, permanent mold and investment), extrusions, forgings, impact extrusions and flat rolled products. It can be joined by riveting or any of the commonly used welding methods. |
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| What are magnesium's major benefits? |
In short, magnesium is light, abundant and recyclable.
Magnesium can be machined faster and has the best strength-to-weight ratio of any of the commonly used structural metals. It has excellent dimensional stability and is highly impact and dent resistant. Magnesium has excellent damping capacity and low inertia which makes it a good choice for parts which undergo frequent and sudden high-speed changes in the direction of motion. The new high purity alloys have corrosion resistance better than carbon, steel and some aluminum alloys. |
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| How much magnesium is produced? |
| While metallic magnesium has been known since 1808 when Sir Humphrey Davy succeeded in isolating small quantities, industrial production did not start until 1886 in Germany, the same year that the Hall-Heroult process for aluminum was discovered. By the turn of the century the entire world production was only ten metric tons per year. By 1990 it was over 350,000 metric tons per year. Experts anticipate that the demand for magnesium will rise significantly over the next few years to reach close to 500,000 metric tons by the year 2005. Producers have kept ahead of the steady increase in demand for magnesium by building new capacity ahead of the demand curve. |
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| What are the primary markets for magnesium? |
The four principal uses of magnesium in an industrial context are:
Alloying with aluminum - 40 - 45 percent
As a structural metal - magnesium alloys - 33 - 35 percent
Iron and steel processing - desulfurization - 13 percent
Electrochemical and other |
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| What is aluminum alloying? |
This is the largest single application for magnesium, accounting for about forty to forty-five percent of total consumption. Relatively small additions of magnesium to aluminum will improve its strength and corrosion resistance.
Many aluminum alloys contain some magnesium. The 5,000 series, frequently called the marine alloys because of their excellent corrosion resistance, may contain up to 5.5 percent magnesium. The 7,000 series, often referred to as the aerospace alloys, may contain up to 3.5 percent magnesium. The ubiquitous aluminum beverage can usually uses alloy 3004 (1.1 percent magnesium) for the can's body and alloy 5182 (4.5 percent magnesium) for the lid. Over 60 percent of the aluminum beverage cans sold in the U.S. today are being recycled, thereby conserving the magnesium component. |
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| What are some structural uses? |
| Magnesium alloys are used in a wide variety of structural applications. While a large number of alloys are in use, the most common contain up to nine percent aluminum, up to two percent zinc and small amounts of manganese. Generally, the alloys of lower aluminum content are used for the production of wrought products while those of higher aluminum content are used mainly for castings. |
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| Die castings: |
One of the fastest growing structural markets for magnesium is die castings, particularly since the introduction of the corrosion resistant high purity alloys in the early 1980's. Typical of the numerous automotive die castings are cylinder head covers, clutch housings, steering columns, wheels, instrument panels and valve covers.
There is a wide diversity of non-automotive die cast parts ranging from computer components, luggage frames, lawn mower decks and chain saw housings to bicycle frames, fishing reels, ski bindings, video and digital camera housings and archery bows. |
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| Thixomolding: |
The latest method to process magnesium alloy. Thixomolding is based on material flow in a semi solid state to achieve thin wall, high density, and complex shaped components. The material is kept at room temperature and is heated in a controlled environment before injection into a mold.
Thixomolded components can be found in the automotive, electronics. power tool, computer and recreational industries. Parts include television housings, PDA covers, eyeglass frames, steering wheels and hand drill components. |
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| Sand cast: |
| Magnesium's low density is especially important for sand cast aerospace applications. Special alloys containing zinc, ziconium, silver, yttrium and rare earths are used for components operating at temperatures up to 300 degrees C (575 degrees F) for extended periods of time. Typical applications include helicopter gear boxes, canopy frames, air intakes, engine frames and speed brakes. |
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| Wrought products: |
| Magnesium is also used in wrought product form such as extrusions, forgings, sheet and plate. Applications for these mill products range from bakery racks, loading ramps, and hand trucks to concrete finishing tools, computer printer platens and nuclear fuel element containers. Magnesium tooling plate is widely used for making jigs and fixtures because of its high dimensional stability and ease of machining. |
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| Besides desulfurization, how is magnesium used in iron and steel processing? |
| Magnesium is an important element in the production of nodular cast iron, which is also known as ductile iron and spheroidal graphite iron. It is produced by introducing a small but definite amount of magnesium and/or rare earths, usually in the form of magnesium bearing ferro-silicon, to the molten iron. This process causes the graphite in the iron to nucleate as spherical particles instead of flakes, thereby imparting higher strength and much greater ductility to the casting. Ductile iron castings are widely used in automotive components and pipe. |
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| What are magnesium's electrochemical and other uses? |
Magnesium anodes are used to prevent galvanic corrosion of steel in certain environments such as underground pipelines, storage tanks and domestic water heaters. The use of magnesium anodes to suppress corrosion and thus decrease leaks in pipelines and vessels contribute both to increase safety and conservation of resources.
Magnesium is also used as a reducing agent in the production of beryllium, titanium, zirconium, hafnium and uranium. Organic chemistry applications of magnesium include important industrial syntheses such as the Grignard reaction.
In finely divided form, magnesium is used in pyrotechnics, either as pure magnesium or alloyed with 30 percent or more aluminum. It is also used in dry cell and reserve cell batteries, principally in military applications.
In the printing industry, wrought magnesium alloy plates are used for photoengraving. Magnesium etches rapidly to provide a sharp impression, and the by-products are less hazardous than alternative metals. |
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| Why use magnesium for structural parts? |
The primary reason for selecting magnesium is its light weight and superior weight-to-strength ratio. Another common reason is its machinability. Other benefits include:
Dimensionally stable
Welds easily
Excellent damping capacity
Impact and dent resistant
Corrosion resistant |
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| What are the principal production processes in use today? |
Two principal production processes are in use today:
Electrolysis of molten magnesium chloride
Thermal reduction of magnesium oxide
Both processes are used to produce significant quantities of magnesium, although currently the majority of production on a worldwide scale is by the electrolytic method.
The magnesium chloride cell feed for the electrolytic process is obtained from the ocean, brines rich in magnesium chloride, residual bitterns from the processing of potash, dolormite or magnesium oxide ores.
The magnesium furnace feed for the thermal reduction process is obtained from magnesium bearing minerals such as dolomite, brucite or magnesite which are widely distributed in the earth's crust. The raw material reserves for either process are virtually inexhaustible. |
