Tungsten Metal Properties | Melting Point, Density, Hardness — Ruixin



Why Pure Tungsten Metal Alone Won’t Solve Industrial Wear Problems

A procurement manager searching for tungsten metal because shearer picks are wearing out at 40 hours per tip is looking at the wrong material. Tungsten’s 3,422°C melting point and 19.3 g/cm³ density are impressive numbers for lamp filaments and counterbalances. They are not what determines tool life on a DTH rig or a shearer drum.

For a system-level diagnosis before changing carbide, continue with the rod blanks for end mills and drills metal properties melting.

The property that makes tungsten valuable for industrial wear applications is not the pure metal — it is tungsten carbide, a sintered composite of tungsten carbide particles bonded with a cobalt matrix. Cemented carbide at HRA 88–93 is substantially harder than pure tungsten’s Mohs 7.5, and the ability to tune cobalt content and grain size gives it a performance range that pure tungsten metal cannot match.

The gap between what buyers search for and what they actually need is costing them in replacement frequency, downtime, and cost per operating hour. The properties of tungsten metal — melting point, density, hardness — are transformed and amplified in the cemented carbide grades that mining and tunneling operations rely on.

Tungsten Metal Melting Point: 3,422°C — and Why It Matters Less Than You Think

Tungsten’s 3,422°C melting point (6,192°F) is the highest of any element, with a boiling point at 5,555°C. For lamp filaments, furnace heating elements, and rocket engine nozzle throats, that ceiling is essential. No other metal sustains structural integrity above 1,650°C while maintaining tensile strength.

But for mining and excavation tools, the operating temperature at the cutting edge rarely approaches these extremes. The relevant failure mechanism in rock cutting is abrasive wear and impact fracture, not thermal degradation. The real question is not whether the material can survive 3,000°C — it’s whether the tool edge can resist abrasion at 200–600°C for the full length of a production shift.

Ruixin’s cemented carbide grades are not designed for the 3,422°C ceiling of pure tungsten metal. They are designed for the 200–600°C range where cobalt washout and thermal fatigue determine actual tool life. SR8C at HRA 89.0 with 8% cobalt resists thermal softening at sustained cutting temperatures above 500°C through grain size control at 2.0–3.0 µm and cobalt distribution — not through the pure tungsten melting point.

Tungsten Metal Density: 19.3 g/cm³ — How It Transforms Into Carbide

Pure tungsten metal at 19.3 g/cm³ has nearly the same density as uranium and 1.7 times that of lead. That density makes it useful for counterbalances, kinetic energy penetrators, and radiation shielding. For cutting tools, the density figure tells a different story.

When tungsten is converted to tungsten carbide (WC) and sintered with a cobalt binder, the density drops. Ruixin’s SR7X grade sits at 14.70 ± 0.05 g/cm³. That is still nearly twice the density of steel (7.8 g/cm³), but lower than pure tungsten because the carbide structure incorporates carbon and the cobalt binder occupies volume without the same mass contribution.

What matters operationally is not the absolute density figure but what it represents: the volume fraction of tungsten carbide particles in the sintered composite. A higher density in carbide grades (14.70 g/cm³ for SR7X vs. 14.45 g/cm³ for SR10C) correlates with lower cobalt content and higher hardness. The density of tungsten metal in the pure form sets the upper bound — carbide grades trade some of that density for the toughness that makes them usable in impact-loaded tools.

Table 1: Density Comparison — Pure Tungsten vs. Ruixin Carbide Grades

Material	Density (g/cm³)	Cobalt Content	HRA Hardness	Primary Trade-off
Pure tungsten metal	19.3	0%	Mohs 7.5 (~HRA 72)	Highest density, lowest toughness
Ruixin SR7X	14.70 ± 0.05	6%	91.0 ± 0.5	Highest wear resistance, lowest impact tolerance
Ruixin SR8C	14.65 ± 0.05	8%	89.0 ± 0.5	Balanced wear/toughness, standard mining grade
Ruixin SR10C	14.45 ± 0.05	10%	88.0 ± 0.5	Highest impact toughness, lower wear ceiling
Steel (reference)	7.8	—	~HRA 65–70	Low cost, low wear resistance

Tungsten Metal Hardness: From Mohs 7.5 to HRA 91.0

Pure tungsten metal ranks at approximately 7.5 on the Mohs hardness scale: harder than glass (5.5) and hardened steel (6–7), but well below topaz (8) and diamond (10). In HRA terms, pure tungsten metal scores approximately HRA 72.

By contrast, Ruixin SR7X at HRA 91.0 is dramatically harder. This jump comes from the tungsten carbide phase itself (WC has a Mohs hardness of 9.0–9.5) combined with a fine grain size of 1.0–1.2 µm that creates a dense, tightly bonded microstructure.

The WC grain size effect on wear resistance is one of the most under-discussed variables in material selection. In the same cobalt content range, a grade with 1.0 µm grain size can deliver 20–30% higher abrasion resistance than a grade with 3.0 µm grain size — at the cost of reduced fracture toughness. This is why Ruixin offers three distinct grain-size profiles across the SR7X, SR8C, and SR10C grades rather than a single “tungsten carbide” option.

For buyers comparing cemented carbide vs tool steel, the gap is even wider. Tool steel tops out around HRA 82–84. The softest cemented carbide grade in Ruixin’s range starts at HRA 88. Tool steel cannot reach that hardness without losing its temper. This is not an incremental improvement — it is a different category of material.

The Cobalt Content and Grain Size Trade-off: What Pure Tungsten Specs Don’t Tell You

The properties of pure tungsten metal are fixed. You cannot tune a block of tungsten for higher toughness or lower wear rate. The advantage of cemented carbide is that the cobalt binder ratio can be adjusted to match the application’s failure mode.

The cobalt content carbide hardness tradeoff follows a predictable curve:

• 6% cobalt (SR7X, HRA 91.0): Maximum wear resistance. Best for pure abrasion applications: DTH buttons in hard granite, wear strips in crushers, nozzles handling abrasive slurries.
• 8% cobalt (SR8C, HRA 89.0): Balanced profile. Standard for roadheader picks, coal mining shearer drums, and road milling inserts where the load includes both abrasion and moderate impact.
• 10% cobalt (SR10C, HRA 88.0): Maximum toughness. The correct choice for high-impact applications: longwall shearer picks in coal seams with hard rock inclusions, heavy-interrupted cutting, TBM tools in mixed ground conditions.

The tungsten carbide cobalt ratio performance equation is straightforward: more cobalt = more toughness and less wear resistance; less cobalt = more wear resistance and less toughness. Grain size modulates both: at 1.0–1.2 µm (SR7X), the fine grain structure adds hardness without changing cobalt content; at 2.0–3.0 µm (SR8C, SR10C), the coarser grain sacrifices some hardness for improved thermal fatigue resistance and crack propagation tolerance.

Grade Selection Table: Matching Tungsten Carbide to Application Conditions

Application Scenario	Recommended Grade	Key Parameters	Why This Grade
DTH drilling in granite (f = 16–18)	SR7X	HRA 91.0, grain 1.0–1.2 µm, 6% Co	High hardness resists the fine-abrasion wear of hard granite; low impact load means fracture risk is minimal
Roadheader cutting in medium-hard sandstone with clay bands	SR8C	HRA 89.0, grain 2.0–3.0 µm, 8% Co	2–3 µm grain absorbs intermittent impact from sandstone inclusions; flexural strength ≥ 2,200 MPa prevents chipping
Longwall shearer in coal seam with hard rock partings	SR10C	HRA 88.0, grain 2.0–3.0 µm, 10% Co	10% cobalt binder absorbs repeated high-impact loads; reduced hardness is acceptable because coal has low abrasivity
Asphalt milling with recycled abrasive overlay	SR8C	HRA 89.0, flexural strength ≥ 2,200 MPa	Consistent wear across hundreds of picks per drum; batch-to-batch density control within ±0.05 g/cm³ prevents uneven wear

Wrong Grade Consequences: Quantified Cost of Mismatch

Selecting the wrong WC-Co grade for an application produces measurable, predictable penalties:

1. Tip life drops 30–50% when a high-cobalt grade (SR10C) is used in a pure abrasion application like granite DTH drilling. The softer matrix wears faster, and the cost per meter rises 20–35% compared to the correct SR7X grade.
2. Replacement frequency doubles when a high-hardness grade (SR7X) is used on a roadheader encountering clay-bound sandstone with intermittent hard inclusions. Chipping failures occur hours into a shift that should run 16+ hours.
3. Cost per operating hour rises 25–40% from unplanned downtime. A chipped carbide tip on a longwall shearer does not just end that tip’s life. It can damage the tool holder or pick box, requiring welding repairs that stop the entire face.
4. Batch variance becomes the hidden cost when undocumented grade changes occur between sample approval and bulk delivery. Reliable carbide suppliers provide per-batch Material Test Reports with density, HRA, and flexural strength — if a supplier cannot or will not provide these, the risk of receiving a different grade with different performance is unacceptably high.

How to Implement This in Your Operation

The transition from understanding tungsten metal properties to specifying the correct cemented carbide grade requires three documented inputs: rock type (or material being cut), machine model (shearer, roadheader, DTH rig, or mill), and current failure pattern (wear rate images or fractured tip photos).

Ruixin manufactures grades SR7X, SR8C, and SR10C in formats compatible with most OEM tooling, including coal tooth carbide tips for shearer drums, road milling picks, DTH spherical buttons, and TBM cutting tools. All grades are produced on a 14,200 m² production floor with up to 500 tons annual capacity, ISO certified, with batch QC data available per shipment.

For a deeper dive into how cobalt content and grain size interact, see our cemented carbide guide on WC grain size and cobalt content. The full range of tungsten carbide wear parts is documented on our tungsten carbide wear parts for mining article for engineering review.

If your conditions fall outside the standard SR7X/SR8C/SR10C parameters, such as unusual rock types, custom tool geometry, or specific performance targets, Ruixin offers custom grade formulation. This is the factory value that trading companies cannot match: the ability to adjust cobalt content by 1–2% or shift grain size by 0.5 µm to solve a site-specific failure mode.

Frequently Asked Questions

How do I choose between pure tungsten metal and tungsten carbide for an industrial application?

The choice depends on your failure mode. Pure tungsten metal is used in applications requiring extreme temperature resistance — filaments, heating elements for furnaces above 1,650°C. Tungsten carbide, bonded with cobalt and sintered, is used where wear resistance and impact toughness are the primary concerns — mining tools, DTH drill buttons, road milling picks, and wear components. Tungsten carbide at HRA 88–91 is significantly harder than pure tungsten metal at approximately Mohs 7.5, and the cobalt binder can be adjusted between 6% and 10% to tune toughness versus wear resistance.

What is the difference between SR7X and SR8C in practical performance?

Ruixin SR7X (HRA 91.0, 6% cobalt, 1.0–1.2 µm grain size) is optimized for high-abrasion, low-impact applications such as wear-resistant components and DTH buttons in hard rock. SR8C (HRA 89.0, 8% cobalt, 2.0–3.0 µm grain size) is a balanced grade that trades some hardness for impact toughness, making it the standard choice for roadheader picks and road milling inserts where the load includes both abrasion and intermittent impact.

Which tungsten carbide grade performs best under high-impact conditions?

For high-impact conditions such as longwall shearer drums cutting coal with hard rock inclusions, Ruixin SR10C is the recommended grade. It has HRA 88.0, 10% cobalt, and a coarser 2.0–3.0 µm grain structure, giving it the highest flexural strength (≥2,200 MPa) of Ruixin’s standard grades. The elevated cobalt binder content absorbs shock loads that would crack a lower-cobalt grade like SR7X within hours of operation in the same application.

How does cobalt content affect tungsten carbide performance?

The relationship is inverse: increasing cobalt from 6% to 10% drops HRA from approximately 91.0 to 88.0, but flexural strength rises from ≥2,000 MPa to ≥2,200 MPa. Higher cobalt content means the carbide matrix is more ductile and can absorb impact without fracturing. Lower cobalt content means higher hardness and superior wear resistance against fine abrasion. The correct cobalt content is determined by whether your primary failure mode is fracture (requiring more cobalt) or excessive wear (requiring less cobalt).

What causes premature tungsten carbide tip failure in mining tools?

Premature failure is most commonly caused by a mismatch between four variables: cobalt content, grain size, rock abrasiveness, and impact frequency. Using a high-cobalt grade (like SR10C) in a pure abrasion environment where the rock has no impact load will cause accelerated wear — tip life may drop 30–50% compared to a lower-cobalt grade. Conversely, using a high-hardness grade like SR7X in high-impact coal seam cutting with hard rock inclusions will cause chipping and fracture within hours. The failure is rarely random — it is the predictable result of a grade-to-application mismatch.

How does grain size affect cemented carbide wear resistance?

Grain size is one of the most important but least discussed parameters. At the same cobalt content, a grain size reduction from 3.0 µm to 1.0 µm can increase hardness by HRA 2–3 points. Ruixin SR7X uses ultra-fine 1.0–1.2 µm grains specifically for maximum wear resistance in pure abrasion applications. SR8C and SR10C use 2.0–3.0 µm grains, which trade some hardness for improved impact toughness and resistance to thermal fatigue. The wrong grain size can cause premature failure even when the cobalt content is technically correct.

Is pure tungsten metal or tungsten carbide better for high-temperature cutting applications?

Pure tungsten metal is better for applications above 1,650°C where the structure must survive extreme heat without deformation — such as furnace elements and rocket nozzles. Tungsten carbide is better for cutting and drilling applications where edge hardness at 200–600°C determines tool life. Ruixin’s SR8C at HRA 89.0 with 8% cobalt resists thermal softening at sustained cutting temperatures above 500°C because its cobalt matrix is stabilized by the WC grain structure — a performance profile pure tungsten metal does not offer.

Get a Custom Grade Recommendation

Tungsten metal properties tell you what the raw element can do. But applying tungsten metal in its cemented carbide form depends on matching the grade variables to your specific conditions.

Send us your application details: rock type, machine model, current tool geometry, and wear pattern photos. Our engineers will confirm the correct Ruixin grade (SR7X, SR8C, or SR10C) and available dimensions within 24 hours. Custom grade formulations are available for non-standard performance requirements.

Email: info@ruixintungstencarbide.com
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