Tungsten Metal Melting Point-Highest of the High-Temperature Metals

Tungsten metal has the highest melting point of any metal, at approximately 3,422°C (6,192°F). Often regarded as the best metal for extreme heat applications, tungsten’s extraordinary heat tolerance makes it invaluable for engineers designing parts like rocket nozzles, furnace elements, and other components exposed to extreme temperatures.

However, this advantage comes with trade-offs – tungsten is very dense, somewhat brittle, and challenging to machine. This article provides a fresh look at tungsten’s melting point and properties, comparing it with other high-temperature metals, and offers practical insights for CNC machining and custom fabrication decisions.

Tungsten’s Unmatched Melting Point at a Glance

To put tungsten’s incredible melting point in perspective, consider these reference points:

• Tungsten (W): ~3,422°C (6,192°F) – highest of all pure metals.
• Tantalum (Ta): ~3,017°C (5,463°F) – second highest metal melting point.
• Iron (Fe): ~1,538°C (2,800°F) – typical steel melts around 1,370°C, far below tungsten.
• Titanium (Ti): ~1,668°C (3,034°F) – high for a lightweight metal, but nowhere near tungsten.

In short, tungsten can endure heat that would liquefy common structural metals many times over. Only a few exotic materials (like carbon or certain ceramics) can remain solid at higher temperatures, but among metals, tungsten stands at the top. This refractory metal property (exceptional resistance to heat) is what makes tungsten so special for high-temperature engineering.

Why Is Tungsten’s Melting Point So High?

The reason tungsten doesn’t melt until such an extreme temperature lies in its atomic structure and bonding:

Strong Atomic Bonds

Tungsten atoms bond together with very strong metallic bonds. A large number of shared d-electrons create a tight, cohesive bond between atoms. It takes an enormous amount of energy to break these bonds apart into a liquid state. In simple terms, tungsten’s atoms “stick” together more strongly than those of most metals, so it requires extreme heat to make them move freely (melt).

Dense Crystal Structure

Tungsten’s atoms are packed in a body-centered cubic (BCC) crystal lattice – each atom is surrounded by eight others in 3D. This dense arrangement means very high cohesive energy: the atoms strongly resist separation. Tungsten also has a high atomic mass (element 74), so its atoms vibrate less at a given temperature compared to lighter metals. All these factors combine to give tungsten one of the highest melting points of any element.

In summary, tungsten’s chemical bonding and structure make it exceptionally thermally stable. It is the prime example of a “refractory metal,” a family of high-temperature metals known for retaining strength at red-hot temperatures. This explains why tungsten can glow white-hot (as in light bulb filaments) without melting, and why it outperforms other metals in extreme heat.

Comparing Tungsten with Other High-Temperature Metals

Tungsten isn’t the only metal used for high-heat environments – it’s part of a group of refractory metals (high-temperature metals) that also includes tantalum, molybdenum, niobium, and rhenium. The table below compares tungsten’s melting point and density with some of these peers:

Tungsten leads in both melting point and density among common refractory metals. For example, tungsten melts ~400°C higher than tantalum and a full 800°C higher than molybdenum. Its density is also the greatest – about 19.3 g/cc, nearly double that of Mo. This combination of ultra-high melting point and heaviness means tungsten can handle heat and also concentrate a lot of mass in a small volume.

By contrast, molybdenum, tantalum, and niobium all have slightly lower melting points and lower densities. They are still considered high-temperature metals, but offer different balances of properties (for instance, tantalum is noted for corrosion resistance, molybdenum for easier machining, etc.). Engineers must weigh these differences when selecting a material for extreme heat: tungsten provides the absolute highest temperature capability, while others may be easier to work or less expensive.

Tungsten vs Molybdenum: Selecting the Right Refractory Metal

A common comparison is tungsten vs. molybdenum, since both are used in high-temperature industrial applications. Here’s how they stack up:

• Melting Point & Heat Performance: Tungsten’s melting point (~3422°C) far exceeds molybdenum’s (~2623°C). If your application pushes above ~2000–2500°C, tungsten is often the only viable metal. Molybdenum can handle very high heat too, but it will soften or melt well before tungsten does. For temperatures below ~2500°C, molybdenum might suffice and is often used to avoid tungsten’s drawbacks.

• Density & Weight: Tungsten is much denser (19.3 g/cm³) than molybdenum (10.2 g/cm³). Tungsten is excellent when you need to concentrate weight (e.g. in ballast or counterweights), but in weight-sensitive designs molybdenum’s lighter weight is an advantage. For aerospace parts, the heavy weight of tungsten could be a limiting factor unless absolutely needed for heat or radiation shielding.

• Machinability: Pure tungsten is notoriously difficult to machine, whereas molybdenum is comparatively easier (similar to machining stainless steel with proper techniques). Tungsten’s extreme hardness and brittleness at room temperature make cutting, drilling, or milling very challenging and slow. Molybdenum, while still a hard metal, is more ductile and can be machined with conventional equipment (albeit with faster tool wear than steel). This means molybdenum is often cheaper to fabricate into parts, whereas tungsten may require specialty machining methods (discussed later).

• Cost & Availability: Tungsten tends to be more expensive per kilogram than molybdenum and is less widely available in standard stock forms. In fact, among the refractories, molybdenum is usually the least costly, while tungsten is moderately high (tantalum and rhenium are much more expensive than tungsten). For budget-sensitive projects, molybdenum can deliver high performance at a lower material cost. Tungsten’s price, coupled with higher machining cost, means you pay a premium for that last measure of heat resistance.

When to choose tungsten vs molybdenum? If your part must survive truly extreme temperatures or intense heat flux that would push molybdenum to its limits, tungsten is the safer choice despite the challenges. On the other hand, if the required temperature is within molybdenum’s range and weight or machinability are concerns, molybdenum might be the more practical option. In some cases, engineers use molybdenum as a backup or base, and incorporate tungsten only in the hottest sections of a design (to balance performance and manufacturability).

CNC Machining Tungsten: Challenges and Solutions

Tungsten’s high melting point comes with mechanical properties that make CNC machining and fabrication a special challenge. Engineers and CNC project managers must account for the following factors when working with pure tungsten metal:

Hardness and Tool Wear

Tungsten is extremely hard (approaching 7.5 on the Mohs scale, similar to hardened steel) and has high strength. Cutting tools encounter significant resistance when machining tungsten. Expect rapid tool wear—carbide tools or even polycrystalline diamond tools are often required to cut tungsten, and they will still dull quickly. Machining tungsten can feel like machining a ceramic in terms of hardness. Budget for more frequent tool changes and use the hardest tool materials available.

Brittleness and Chipping

Despite its hardness, tungsten is brittle at room temperature. It can crack or chip if machined aggressively. This means you must use conservative cutting parameters: low feed rates and shallow depths of cut to avoid shock to the material. Even with care, edges may crumble instead of forming a clean chip. Pre-heating the tungsten workpiece (to a few hundred degrees) can sometimes improve its ductility slightly, but this is not always practical. Operators must be vigilant to avoid sudden tool engagement or excessive force which could shatter the part.

Heat Conductivity

Tungsten has high thermal conductivity, so it rapidly conducts heat away from the cutting zone into the tool. While this prevents the tungsten from local overheating, it heats the cutting tool quickly, which can degrade tool life. To counter this, use plenty of coolant and ensure good heat dissipation during machining. The high heat conductivity also means tungsten doesn’t “soften” much when cutting – unlike some metals that get easier to cut as they heat, tungsten stays hard, keeping cutting difficult throughout.

Preferred Machining Methods

Traditional milling or turning of tungsten is often replaced or supplemented by non-traditional machining methods. Grinding is commonly used for finishing tungsten parts since abrasive wheels can slowly wear down the material. Electrical Discharge Machining (EDM) is a popular method to cut or shape tungsten; since EDM uses spark erosion, it is not hindered by tungsten’s hardness. Laser cutting and waterjet (with abrasive) can also cut tungsten for profiles.

These methods avoid the direct tool-metal contact that makes conventional machining tough. If possible, plan to use grinding or EDM for intricate features instead of only end mills or drills.

Slow Material Removal

All the above factors result in slow machining speeds. Cutting tungsten is a gradual process – material removal rates are much lower than for aluminum or steel. CNC programmers often have to adjust CAM strategies to use multiple shallow passes, and allow for tool cooling breaks. This slows production, so fabrication lead times for tungsten parts are longer. It’s wise to inform stakeholders that machining tungsten is a specialized task requiring patience and expertise.

No Conventional Casting or Forming

Tungsten’s high melting point also affects how you obtain the material before machining. It’s not commercially feasible to cast large pure tungsten ingots or do typical foundry work – no standard furnace can readily melt it. Instead, tungsten stock (plates, rods, etc.) is usually produced by powder metallurgy: tungsten powder is pressed and sintered at high temperature to create a solid piece.

These sintered blanks are what you’ll machine. Forging and rolling operations for tungsten are limited and require high heat; welding tungsten is extremely difficult as well. In practice, expect to machine tungsten in the state you receive it (sintered bar or plate), rather than being able to cast or weld it into a near-net shape. This influences design for manufacturing: simple shapes are easier to achieve, and complex geometries might need to be split into assemblies or considered for alternative manufacturing like additive manufacturing or using tungsten alloys (discussed next).

Bottom line: Machining pure tungsten is possible but demands careful planning, specialized tooling, and plenty of patience. Many machine shops will opt for tungsten alloys or composites when feasible, as described below, to make fabrication more practical.

Tungsten Alloys for Industrial Use

Because pure tungsten is challenging to work with, industry often uses tungsten alloys and composites to harness tungsten’s benefits in a more convenient form. These materials combine tungsten with other elements to improve machinability, toughness, or to add other properties. Below are some of the most common tungsten alloys and their uses:

Tungsten Heavy Alloys (W-Ni-Fe / W-Ni-Cu)

These are alloys containing about 90–97% tungsten with a balance of nickel and iron or copper binders. Tungsten heavy alloys (often sold under trade names like Densalloy) are made by powder metallurgy – the additives allow the tungsten to sinter into a tough, workable material. They are much easier to machine than pure tungsten, while still retaining very high density and good (though slightly reduced) temperature resistance.

Heavy alloys are used in industrial applications where tungsten’s density is needed but some ductility and machinability is also important: for example, aircraft counterbalances, CNC machined radiation shielding parts, vibration dampening weights, and military penetrators.

Engineers choosing heavy alloy should note the melting point is lower than pure tungsten (the alloy’s behavior is limited by the binder, which might melt around 1,450°C for Ni-Fe). So, heavy alloys are not suited for the highest temperature environments, but they excel in high-density applications and can be precision machined with standard carbide tools.

Tungsten Carbide (WC)

Technically a carbide ceramic rather than a metallic alloy, tungsten carbide is a compound of tungsten and carbon, usually cemented with a small percentage of cobalt or nickel. It is one of the hardest materials commonly used in industry – significantly harder than steel – and retains this hardness even at red-hot temperatures.

Tungsten carbide’s melting point (~2,770°C) is lower than pure tungsten, but it’s still very high. The chief use of tungsten carbide is in cutting tools and wear-resistant parts. In fact, about 50% of all tungsten produced is used to make tungsten carbide tools for machining other metals, mining drill bits, milling cutters, and so on.

These tools can cut at high speeds without losing their edge due to heat. For CNC project planners, it’s worth noting that while you might not machine tungsten carbide (it usually requires grinding), you will likely use tungsten-carbide tools to machine everything else. Tungsten carbide exemplifies tungsten’s value in high-temperature, high-wear scenarios – it enables tooling that lasts in conditions where ordinary tool steels would soften or erode.

Tungsten-Copper Composites (W-Cu)

Tungsten-copper is not a true alloy (since tungsten and copper do not form a solid solution) but rather a sintered composite – typically 70–90% tungsten with 10–30% copper. It combines properties of both metals: tungsten’s ability to withstand heat and arc exposure, with copper’s excellent thermal and electrical conductivity.

Tungsten-copper is used for specialized high-heat applications such as electrical contacts in high-voltage switches, electrodes for EDM and resistance welding, and thermal management components. Notably, it’s used in aerospace for rocket engine nozzle inserts and throat liners. In these extreme environments (e.g. re-entry vehicles or missile engines), the copper phase in W-Cu actually provides a cooling mechanism – at very high temperatures (around 3,000°C), the copper can melt and vaporize, carrying away heat (a sort of self-cooling “sweat” effect).

This helps protect the remaining tungsten structure from overheating. Tungsten-copper parts can be machined by EDM or careful machining (the softer copper phase makes it a bit friendlier than pure tungsten), and they offer a clever balance: structural integrity under heat (from W) plus heat dissipation (from Cu). For industrial use, tungsten-copper is also common in electrical applications where contacts must endure arcing without melting.

Other tungsten alloys and uses include tungsten-molybdenum alloys (to combine high-temperature strength with improved ductility), tungsten as an alloying element in steels (e.g. high-speed tool steels use tungsten for hardness at temperature), and even emerging tungsten-based superalloys. But the three categories above – heavy alloys, tungsten carbide, and W-Cu – are the most widely used in CNC fabrication and engineering projects. They allow engineers to leverage tungsten’s unique properties in a more workable form when pure tungsten is impractical.

Applications of Tungsten in Extreme Heat

Thanks to its high melting point and resilience, tungsten (and its alloys) find use in some of the hottest and most demanding applications in industry. Below are a few key areas where tungsten truly excels:

Aerospace and Rocket Components

Tungsten is used in the aerospace industry for parts that must survive intense heat and pressure, such as rocket engine nozzle throats, propulsion system components, and even parts of re-entry heat shields. For example, certain rocket nozzles in missile systems have used tungsten liners to withstand the scorching combustion gases.

Tungsten’s ability to stay solid and retain strength in these environments makes it invaluable for rockets and jet engines. (In some designs, tungsten-copper composites are chosen to manage heat as mentioned earlier.) The downside – its weight – means tungsten is used strategically in areas of highest thermal stress.

Industrial Furnaces and Heating Elements

Tungsten can operate at temperatures where almost no metal could. High-temperature furnace components like heating elements, crucibles, and heat shields are often made of tungsten or tungsten alloys.

In glass melting furnaces, tungsten electrodes stir molten glass; in high-vacuum furnaces, tungsten heating coils can run white-hot. Even the humble incandescent light bulb filament is made of tungsten wire, glowing at ~2,500°C inside a bulb.

No other metal would survive as a fine filament at that temperature without melting. Tungsten’s low vapor pressure at high temp also means it evaporates slowly, prolonging filament life. While incandescent bulbs are less common now, tungsten’s role in heating elements is still critical in industrial settings (e.g. halogen lamps, vacuum furnace filaments).

Welding Electrodes (TIG Welding)

In the Tungsten Inert Gas (TIG) welding process, a tungsten electrode is used to create an arc that melts the workpiece, but the tungsten electrode itself must not melt. Tungsten is ideal here because it can carry the welding arc’s heat (which can exceed 3,000°C in the arc spot) and remain solid.

TIG welders often use tungsten electrodes doped with thorium or lanthanum for better electron emission, but the base is tungsten. This is a direct application of tungsten’s high melting point in manufacturing technology.

High-Temperature Molds and Tooling

Tungsten and tungsten alloys are used to make molds, dies, and tooling that operate at high temperatures. For instance, injection molds for certain glass or high-temp polymer parts may use tungsten inserts.

Similarly, electrodes for electrical discharge machining (EDM) are sometimes tungsten (or W-Cu) because they maintain shape while generating sparks. Tungsten’s dimensional stability (very low thermal expansion) keeps such tooling accurate even as temperatures rise.

Using Tungsten in Your Project: Practical Considerations

For engineers and procurement managers evaluating tungsten for high-temperature projects, here are some key takeaways and tips:

Unmatched Heat Resistance

If your design must survive extreme heat (2000°C+) or prolonged high-temperature operation, tungsten is typically the go-to metal. It outperforms other high-temperature metals like molybdenum or tantalum when it comes to maximum service temperature. Use tungsten when no other metal can handle the heat, such as certain furnace parts, aerospace hot-zone components, or cutting tools facing intense friction.

Weight and Strength Trade-off

Remember that tungsten is very heavy and also brittle at low temps. If weight is a critical factor or the part sees impact/loading at room temperature, pure tungsten might pose issues. In weight-sensitive high-heat applications, consider if a lighter refractory metal (like molybdenum or a superalloy) could meet requirements.

Alternatively, you might use tungsten only in specific hotspots and lighter structure elsewhere. Always account for tungsten’s 19.3 g/cc density in your designs – it can significantly increase mass of a component.

Machining & Fabrication Challenges

Plan for specialized manufacturing when choosing tungsten. CNC machining tungsten requires carbide or diamond tools, low speeds, and likely processes like EDM or grinding. This means longer lead times and higher machining costs. Ensure your vendors have experience with tungsten, or be prepared for a learning curve.

For complex shapes, explore modern methods like additive manufacturing (3D printing) of tungsten or using pre-sintered near-net shapes, since conventional cutting is so slow. If tolerances are tight, tungsten’s minimal thermal expansion is a bonus (it will hold size as it heats), but achieving those tolerances on a machined surface will take effort.

Use Alloys to Your Advantage

Don’t overlook tungsten alloys and composites as an alternative to pure tungsten. If you can tolerate a slight drop in melting point or an addition of other elements, materials like tungsten heavy alloy (W-Ni-Fe) can dramatically ease fabrication. Tungsten heavy alloys still give ~90% of tungsten’s performance but can be turned, milled, and drilled with relative ease – a huge cost and time saver.

Similarly, tungsten-copper can be considered for parts like arc contacts or thermal components to simplify manufacturing while meeting performance (plus it offers that built-in cooling effect). Always weigh whether a tungsten alloy might meet your needs at a lower overall project cost.

Cost and Supply

Tungsten is not a cheap material. It is more expensive per unit weight than common steels and aluminums, and even versus other refractories, tungsten sits in the mid-to-high price range (less costly than tantalum or rhenium, but more than molybdenum). Additionally, the global supply of tungsten is concentrated (a significant portion comes from a few countries), so consider supply chain reliability for large quantities.

When budgeting, account not just for raw material cost but also the specialized tooling and slower production rate – tungsten parts will likely cost more and take longer than the same geometry in steel. However, keep in mind that using a material that survives where others would fail can prevent costly failures in service, often justifying the upfront expense.

In conclusion, tungsten metal offers a unique combination of extremely high melting point, strength at temperature, and density that make it indispensable for certain engineering challenges. For CNC project decision-makers, the key is to leverage tungsten’s strengths (heat resistance, stability) while mitigating its difficulties (machining complexity, weight, cost).

By comparing it with other high-temperature metals and considering tungsten alloys, you can make an informed decision on whether tungsten is the optimal choice for your application. When the conditions demand the best metal for extreme heat, tungsten is very often the answer – just go in with a plan for how you will shape it and handle it, and you’ll unlock the full potential of this remarkable metal in your projects.