Tungsten, element 74 of the periodic table, has come a long way since its early use as a material for filaments in lightbulbs. This silvery-white lustrous metal is becoming more present in the industry thanks to the alloying process – that is, the ability to add metallic elements together to create new, improved materials known as alloys. Tungsten can act as both an alloy base and an alloying element, and this article will compare elemental tungsten with its most common alloy, tungsten carbide. Both forms can be found in numerous applications, and this article will help distinguish each type of tungsten from the other by comparing the physical, mechanical, and working properties of each. By doing so, this article aims to help designers make more informed material choices, as well as show the unique characteristics of these advanced metals.
Graphic illustration of element 74, tungsten, from the periodic table of the elements.
Tungsten and its alloys are prized for their strength and stability over temperature.
Image credit: concept w/Shutterstock.com
Tungsten
Originally dubbed ‘wolfram’ in 1779, tungsten (tung sten, or “heavy stone” in Swedish) is a dense metal first isolated in the late 1700s. Since then, it has become increasingly important to the field of material science, as it shows some interesting and valuable properties. These includes excellent high temperature resilience, the lowest expansion coefficient of any metal, the highest melting point of any metal (3370°C/6100°F), the lowest vapor pressure of any metal, high moduli of compression and elasticity, good electrical conductivity, and a high density (19.25 g/cm3), just to name a few. When alloyed with other metals, tungsten can provide some of these properties to the resulting alloy, especially its high strength and resilience. There are, therefore, many tungsten alloys (explained further in our article on the types of tungsten alloys), as well as many other metals such as steel and aluminum that benefit from the addition of tungsten to them.
Tungsten is notoriously difficult to work with while in its impure state, as it’s low ductility predisposes it to shatter. It is brittle at room temperature, and so must be cut/formed well above its transition temperature and cannot be cold-tooled. Tungsten can be ground, joined, milled, riveted, spun, stamped, and turned, but it must be handled with great care, as it is prone to breaking and is generally an expensive material to work with. Pure tungsten is much easier to work, being able to be cut with a hacksaw and is much less brittle, but this pure state is more expensive and is reserved for niche applications. It has good corrosion resistance, only attacked by mineral acids, and oxidizes in the presence of oxygen at high temperatures. An interesting fact about tungsten is that when in a powder state, tungsten can spontaneously ignite in the presence of air (so, machinists beware).
Tungsten is useful for glass-to-metal seals, as its thermal expansion coefficient is on par with borosilicate glass, and finds many uses in lamp filaments, television tubes, electrical contact points, x-ray targets, heating elements, and other high-temperature applications. It is most popular usages are in dry lubricant (tungsten disulfide) and alloys such as high-speed tool steels, hard metal, and of course tungsten carbide – but more on that in the next section.
Tungsten Carbide
Tungsten carbide is an alloy made of tungsten and carbon, made by heating tungsten powder with carbon and hydrogen at 1,400 – 1,600°C (2,550 – 2,900°F). The resulting alloy is 2-3 times as rigid as steel and has a compressive strength surpassing all known melted, cast, and forged metals. It is highly resistant to deformation and keeps its stability at both extreme cold and hot temperatures. When in its monocarbide form (chemical formula of WC), tungsten carbide rivals diamond for the hardest known material. Its impact resistance, toughness, and resistance to galling/abrasions/erosions are exceptional, lasting up to 100 times longer than steel in extreme conditions. Its properties place tungsten carbide in the metal-like substances since it is technically a ceramic cement of tungsten, carbon, and some binder (often cobalt), which is also why it cannot be heat-treated in any way. It has a density of 15.7 g/cm3 and is generally not the best electrical conductor; however, it conducts heat much faster than tool steel.
It is incredibly difficult to machine tungsten carbide, as most machine bits and tools are made of tungsten carbide themselves. Tungsten carbide is generally only milled or lathed and is done so when in its soft, or “green” state, and can only be done with diamond-coated bits. It can also be cast and rapidly quenched to form an extremely hard crystal structure. Tungsten carbide is invaluable in making hardmetal, which is a form of tungsten carbide, as well as making mill products, high-speed tools, military weapons, armor, and other rugged applications.
Is Tungsten Carbide a Metal?
No, tungsten carbide is not a metal. It’s a metal and ceramic hybrid composed of tungsten and carbon atoms. The resulting material exhibits metal-like properties such as high hardness, strength, and thermal conductivity, but its structure is more akin to that of a ceramic.
Tungsten vs. Tungsten Carbide
Tungsten is a chemical element, while tungsten carbide is a compound composed of tungsten and carbon. Tungsten carbide is known for its exceptional hardness and wear resistance, making it a widely used material for cutting tools, jewelry, and various industrial applications, whereas pure tungsten is often utilized in electrical and high-temperature applications due to its unique properties.
Most people will confuse tungsten and tungsten carbide, as tungsten carbide is the most widely understood form of tungsten available. However, there are some niche use cases for its pure form, and this section will contrast tungsten and tungsten carbide to illustrate how they differ. Below, in Table 1, is shown several mechanical properties of each material, and their comparison should give readers a better idea as to when to implement one material over the other. Note that mono tungsten carbide (WC) is used for this comparison, but more alloys exist.
What Are the Properties of Tungsten Carbide and Tungsten?
The properties of tungsten carbide and tungsten are modulus of elasticity, shear modulus, tensile yield strength, thermal conductivity, and hardness (Rockwell A). Below, we compare the properties of each.
Table 1: Comparison of Material Properties Between Tungsten and Tungsten Carbide
材料特性
Tungsten (Metric)
Tungsten (English)
Tungsten Carbide (Metric)
Tungsten Carbide (English)
弾性係数
400 GPa
58000 ksi
669-696 GPa
97000-100000 ksi
Shear Modulus
156 GPa
22600 ksi
260-298 GPa
37700-43220 ksi
Tensile Yield strength
350 MPa
50800 psi
140 MPa
20300 psi
熱伝導率
163.3 W/m-K
1133 BTU-in/hr-ft²-°F
28-88 W/m-K
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