With efforts underway to ban lead-based ammunition as a potential health and environmental hazard, scientists are reporting new evidence that a prime alternative material for bullets -- tungsten alloys-- may not be a good substitute The report, which found that tungsten alloys accumulate in major structures of the immune system in animals, appears in ACS' journal Chemical Research in Toxicology.

Jose Centeno and colleagues explain that tungsten alloys have been introduced as a replacement for lead in bullets and other munitions. It resulted from concern that lead from spent ammunition could harm wildlife when it dissolves into water in the soil, streams, and lakes. Scientists thought that tungsten alloys were relatively non-toxic, and a "green" replacement for lead. Recent studies suggested otherwise, and with small amounts of tungsten alloys also used in some artificial hips and knees, Centeno's group decided to gather further information on tungsten alloys.

They added small amounts of  tungsten compound to the drinking water of laboratory mice, used as surrogates for people in such research, and examined the organs and tissues to see exactly where tungsten ended up. The highest concentrations of tungsten were in the spleen, one of the main components of the immune system, and the bones, the center or "marrow" of which is the initial source of all the cells of the immune system. Further research, they say, will be needed to determine what effects, if any, tungsten may have on functioning of the immune system.


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Tungsten heavy alloy, also called tungsten heavy density alloy. Its main component is tungsten which consist of 85-98%. Therefor the first step of manufacturing heavy alloy is to mix the metal powder, and then trough pressing and liquid-phase sintering processes.

Tungsten heavy alloy is excellent in high density, high strength, good electric and heat conduction.Tungsten heavy alloy has the advantages of good corrosion resistance and antioxidant activity. Besides,
Tungsten heavy alloy has good capability in absorbing rays.

Tungsten heavy alloy is used in nuclear shielding, vial shield, isotope container, high- temperature die, electrical rivet, tungsten sinker bar, shrapnel head, golf and tungsten alloy dart parts spheres. It is core for armourpiercing bullet measurement.


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Tungsten alloy in high temperature tooling is called as tungsten alloy extrusion dies and die casting components.

Tungsten alloy can save time and money in hot metal working. The high tungsten content offers good resistance to thermal cracking, erosion, soldering and the effects of heat cycling in hot metal working processes. Experience has shown that, due to its non-wetting properties, tungsten alloy has significantly increased longevity over the equivalent parts in steel or cast iron. Tungsten alloy does not require heat treatment before use.

Tungsten alloy can save time and money in the extrusion of copper and copper alloys because its high tungsten content offers good resistance to metal pick up, erosion, soldering and the effects of heat cycling such as thermal cracking. This significantly increases the operating life of die inserts compared to the same components made from steel or stellite.


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In recent years, there has been an increased desire to replace depleted uranium (DU) anti-armor penetrators with tungsten heavy alloy (WHA) penetrators. However, the ballistic performance of WHA does not compare with that of DU.

Many methods of improving the ballistic properties of tungsten heavy alloys have been explored. One recent method includes jacketing a long thin core of WHA with a more ductile metal. However, applying thermal-sprayed coatings onto a tungsten substrate is a challenge. The differences in the coefficients of thermal expansion (CTE) make it difficult to achieve adequate adhesion of most coatings to tungsten. Further compounding the problem are residual stresses inherent in thermally sprayed coatings. The thicker the coating desired, the more likely disbonding will occur upon cooling of the substrate. Early attempts to apply an Ni coating (0.0lOA).020 in thick) to a tungsten substrate yielded immediate disbonding and/or cracking of the coatings. The work presented is an investigation focusing on modifications to spray parameters and the use of multiple thin layers to minimize heat transfer and achieve better adhesion.

The use of a material with a CTE nearer to that of tungsten heavy alloys as a bond coat and grading of coating materials was also examined as a method for increasing the overall adhesion of the coating system.


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Tungsten heavy alloys comprising by weight from about 80 to about 100% tuten and from about 0 to about 20% of one or more heavy alloying metals are produced by introducing powders of tungsten and the alloying metals into a thermal spray plasma gun, melting the powders in the hot zone of the gun to form a molten alloy and then spraying the molten alloy in droplet form into a collecting chamber where the droplets are solidified, and the resultant alloy in powdered form is collected. The powdered alloy can be further mixed with powdered copper, iron, nickel, cobalt or tantalum and compacted by dynamic or explosive compaction to form a near full density material. Full density materials are produced by further thermomechanical processing of the compact.

Tungsten heavy alloys, which are of great value in counter weights for aircraft, in ballistics, and in other applications, are conventionally produced by liquid phase sintering of mixed elemental powders. Alloys produced by this method are generally two-phase composites consisting of rounded tungsten grains dispersed in an alloy metrix.

The mechanical properties of tungsten heavy alloys are strongly dependent upon their specific microstructural features: for example, the grain size, contiguity, dihedral angle and the volume fraction of the tungsten phase. For a given tungsten content, the optimal microstructure exhibits low contiguity, small grain size, and strong W-W grain boundary and W-matrix interface.


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There are various kinds of tungsten heavy alloy products, like tungsten heavy alloy rod, tungsten heavy alloy plate, etc.. This article is talking about tungsten heavy alloy main applications.

Tungsten heavy alloy can be used in many fields due to its excellent properties, such as small capacity but high density. When it comes to tungsten heavy alloy main applications, tungsten heavy alloy could be widely used for different industries and countries in various fields, such as the sports, including golf, fishing, darts, racing cars and others. Tungsten heavy alloy can be used in the medical treatment, like radiation shielding, isotope container, source holder. Tungsten heavy alloy can also be used in the scientific field, like tungsten heat sinks, oil drill, mine exploration and others. Tungsten heavy alloy is also used as a substitution in some military products for Depleted Uranium.

For its high melting point, tungsten heavy alloy is usually used in high temperature fields. Tungsten heavy alloy is friendly to the environment, so tungsten heavy alloy can be produced into fishing sinker, jig and other products. Due to its special properties, tungsten heavy alloy is very popularly applied in our daily life.


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Mixing tungsten with carbon creates a strong material called tungsten carbide. The material has become increasingly popular in many industries around the globe. Its uses range from construction tools to jewelry to weapons.

Facts
Tungsten's atomic number on the Periodic Table is 74; its atomic symbol is W. The element is highly resistant to bases and acids. Tungsten's melting point of 3,422 degrees Celsius is the highest of any metal. Hard by itself, tungsten becomes even more durable when combined with carbon, as well as nearly scratch resistant.

Uses
Tungsten carbide is used to make cutting tools for metalworking, drilling construction and mining. Its strength makes it a popular material for jewelry, such as rings, bracelets and necklaces. Weapons makers use tungsten carbide to produce armor-piercing ammunition.

Comparisons
Tungsten carbide is a much more versatile material than most other metals. It is four times as hard as titanium and twice as hard as steel. Tungsten carbide is much more heat resistant than both metals as well.

History
Tungsten was discovered in 1758 and first separated from wolframite in 1793. In the 20th century, tungsten carbide became best known as the material for light bulb filaments. Tungsten carbide was widely used in World War II for making weapons.

Sources
Leading producers of tungsten carbide include China and Russia. Canada, Bolivia and the United States have large reserves. Some 30,000 tons of tungsten carbine are produced annually.


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With very sharp cutting edges and slot type, the cutting force of tungsten solid carbide cutting tools is small in aluminium alloy machining, and it also include the advantages of high chip space and smooth chip removal. So gradually the solid tungsten carbide cutting tools replaces of the high speed steel cutting tools.

In addition, the elastic modulus of tungsten carbide is about 3 times of steel, which means that under the same load, the deformation of tungsten solid carbide cutting tools is only a third of indexable cutting tools. As helical tooth end mill, solid tungsten carbide end mill can smoothly cut into and out. Its chip removal is also very smoothly, all of that helps to decrease the fluctuation of cutting force to restrain the vibration trends.

Tungsten solid carbide cutting tools system can bring potential advantage for aluminum rough machining and finish machining, especially the use of 25 to 100 mm medium to large cutting tools. To be used for aluminum alloy processing, tungsten solid carbide cutting tools has better security, versatility,higher metal removal rate and unparalleled performance without grinding again. However, many cases of finish machining can't reach the required level. But now, Sandvik Coromant’s CoroMill790 can achieve this through new cutting edge, blade, blade bearing and the clamping technology.


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Some tungsten carbide end mills that have been used can be reground to use over again. This saves money and can often be done in the shop while a cycle is being run or by another machinist when he has some down time.

Benefits
Regrinding end mills allows them to be reused which can save a machine shop hundreds of dollars a year. Some end mills are used for profiling only and the dull area can be removed and the bottom reground for further use.

Procedure
Cut the used area off using a cut-off saw. Place the end mill in an end mill sharpening holder, which set the end mill at the right angle for regrinding. Grind the bottom of the end mill to achieve a new, sharp edge for bottom cutting using a surface grinder.

Considerations
If you do not have the capabilities to regrind the end mills in your shop, you can have it done professionally. If the price is less than a new end mill, that route would be preferred to buying new end mills.


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1. Attach the diamond wheel to your bench grinder. Refer to your manual to ensure that the wheel is properly attached and the grinder itself is appropriately mounted.

2. Hold your tungsten carbide tool against the rest beneath the wheel. Touch the tip to the wheel, but do not turn on the grinder yet. Adjust the rest as needed so that you achieve the necessary grinding angle for your particular tool. Many rests will allow you to adjust both the height and the angle of the rest.

3. Remove the tool from the rest, then turn on the grinder. Touch the tip of the tool to the moving wheel, just as you did before when determining the angle, and use the rest to guide the angle of the grinding. Carbide may emit short red sparks during grinding. These are normal. The carbide tool may also become very hot. Work in short intervals and do not burn yourself, overheat the tool or touch the tool immediately after grinding. Continue grinding until the tool is sharpened.


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