Does Tungsten Carbide Rust? Truth About Its Corrosion Resistance

Tungsten Carbide, due to its hardness and resistance, is an extremely durable alloy used in molds, cutting tools, valve components and mining tools. However, customers purchasing Tungsten Carbide products often wonder does tungsten carbide rust?

This article provides a thorough answer to this question by detailing the material’s composition, susceptibility to corrosion and protection instructions. Let’s go!

Part 1. What Is Tungsten Carbide?

Tungsten Carbide, also referred to as “carbide” or “cemented carbide,” is an alloy made of tungsten (W) and carbon (C), created through high temperature sintering process. To enhance mechanical strength and manageability, metal binder such as cobalt (Co) or nickel (Ni) binder is typically added for enhanced performance and handleability; creating an extremely hard, dense alloy with unparalleled combination of hardness and strength.

Tungsten carbide features many beneficial characteristics, including:

Unusual Hardness: Tungsten carbide ranks second only to diamond on the Mohs hardness scale and thus ranks as one of the hardest materials ever known to man. Due to this exceptional hardness, Tungsten carbide can easily machine, drill and cut other hard materials without difficulty.

Excellent Wear Resistance: Due to their hardness, diamond tools exhibit exceptional wear resistance that ensures long tool and component lifespan even under harsh operating conditions.

Excellent Heat Resistance: Tungsten carbide boasts superior heat resistance, withstanding high temperatures without suffering significant loss in mechanical strength – this makes it ideal for high-speed machining in high temperature environments as well as applications in these settings.

Chemical Stability: While not entirely inert, tungsten carbide has proved itself chemically stable in most environments and exhibits good corrosion and oxidation resistance in most situations.

Due to these advantages, tungsten carbide finds wide usage in various industries including:

• Tooling and Machining – for milling bits, drills, and cutting tools.
• Mold and Die Making – to make hard materials like metal or plastic into shape.
• Oil & Gas and Mining – in wear parts like drill bits, nozzles, and valves.
• Aerospace and Defense – in high-performance parts that must be extremely resistant to wear.

Tungsten carbide is an engineered material of toughness and long duration, ideal for applications where normal metals would fail instantaneously.

Part 2. Does Tungsten Carbide Rust?

Short Answer: Tungsten carbide in itself is extremely corrosion resistant; it should not, however, be considered completely immune to it.

WC (tungsten carbide material) is chemically inert. It does not react with oxygen or water easily at all, thus eliminating “rust” such as pure regular iron or carbon steel would. Under standard atmospheric conditions, plain pure tungsten carbide should neither be harmed by exposure to water nor air.

Nonetheless, tungsten carbide (WC) is not composed entirely of WC itself. In order for its grains to be bonded and for it to be strengthened, binder metals like cobalt (Co) or nickel (Ni) are incorporated in order to reinforce it as a composite material; unfortunately, these kinds of metals tend to be corrosion-prone in specific environmental conditions.

Corrosion risks should be anticipated in the following instances:

High humidity or extended immersion: Wet environments, if they are further poorly ventilated, may accelerate oxidation of the binder phase and provoke degradation.

Basic or acidic solutions: Any chemical exposure–e.g., commercial cleaning products, acid or base–will loosen the binder metals.

Marine or salty environments: Chlorides present in saltwater or salt spray can lead to pitting corrosion of cobalt or nickel binder material, leading to pitting corrosion of binder components.

Under such conditions, corrosion occurs not in the tungsten carbide but in its binder metal component and causes material weakness or surface degradation over time. This may appear as discoloration, spottiness or structural weakening depending on exposure levels and length of exposure duration.

Though “tungsten carbide rusts” isn’t entirely accurate, there may be slight surface oxidation or corrosion as a result of exposure to harsh environments or prolonged use, particularly due to metallic binder’s unique behavior.

Part 3. Typical Signs of Corrosion on Tungsten Carbide

Though tungsten carbide is generally considered resistant to corrosion, long-term exposure to harsh environments like high humidity, acid or base solutions, or salt can result in degradation that occurs predominantly within its binder phase. Below are a few signs that corrosion has begun:

1. Dull or Mottled Surface Appearance

One of the earliest telltale signs of corrosion is a noticeable change to its surface luster. A component that once had an appealing, shiny appearance may soon begin to look dull, mottled or stained due to corrosion caused by binder metal (e.g. cobalt or nickel), altering reflectivity at its surface and giving off an aged or dirty impression of itself.

2. Binder Leaching, Discoloration, or Oxidation

In corrosive environments, the binder material will probably seep out over a long period or oxidize and lead to visual surface staining or discoloration. This is most common if the part is exposed to an alkaline or acid solution. You can observe brown or a greenish tinge, depending on the type of binder material utilized and chemical used. In some cases, there may be powdery deposits that form, especially in corners or joints.

3. Localized Pitting or Rust Spots

Even though the tungsten carbide grains themselves are highly corrosion-resistant, the binder surface that is exposed can develop small rust-colored spots under salt-contaminated conditions (e.g., coastal or marine exposure). They might appear as minute rust stains or pitting, typically in surface defect, scratch, or regions with poor surface finish.

Part 4. Do These Types of Corrosion Affect Tungsten Carbide Performance?

In most cases, surface corrosion does not have a deep impact on the strength, hardness, or wear resistance of the tungsten carbide component, especially for regular applications. The structural core of the component remains intact, and the tungsten carbide phase remains well in stressful and abrasive situations.

However, in precision applications—such as aerospace components, precision molds, or sensitive cutting tools—very minor surface corrosion can impact:

• Dimensional accuracy
• Surface smoothness and friction behavior
• Aesthetic look (important for consumer products or premium products)

Therefore, proactive protection for pieces that will likely come into contact with moisture, chemicals or salt is strongly advised.

Part 5. How to Prevent Corrosion of Tungsten Carbide?

Tungsten carbide naturally resists corrosion from rust and chemicals; however, protective procedures can extend its useful life in more challenging or sensitive applications. Here are a few effective strategies for combatting corrosion:

1. Select an Appropriate Grade

To start off properly, it is essential that you select an apt grade of tungsten carbide. Not all grades of tungsten carbide offer equal corrosion protection capabilities – for instance:

Nickel-bonded carbide is less corrosive than cobalt-bonded carbide and best suited for chemical or humid environments.

Producers offer anti-corrosion additives or binders of special grades for use under harsh working conditions.

The use of materials with corrosion resistance incorporated will reduce the risk of premature surface deterioration from the outset.

2.Utilize Surface Treatments

Special surface treatments can enhance the corrosion resistance of tungsten carbide parts. Some of the common methods are:

Nickel Plating – Applies a thin chemical- and oxidation-resistant protective coating.

PVD Coating (Physical Vapor Deposition) – Thin hard, wear- and corrosion-resistant film over very thin metal films (e.g., TiN, CrN) that does not change dimensions.

Nitriding or Passivation – Alters the chemistry of the surface to increase hardness and chemical stability.

These processes are particularly apt for high-precision parts or tools utilized in marine, medical, or chemical environments.

3.Avoid Contact with Corrosive Media

Wherever practicable, minimize exposure to corrosive media such as:

• Strong acids (e.g., hydrochloric or sulfuric acid)
• Strong bases (e.g., sodium hydroxide)
• Saltwater or salt spray

Where exposure cannot be minimized, consider applying a protective sealant, a coated form of the part, or flushing and cleaning the component on a regular basis to remove chemical residues.

4.Store in Dry, Ventilated Area

Proper storage is needed to prevent passive corrosion during downtime. Recommendations are:

• Keeping parts dry in a low-humidity area
• Not exposing to high moisture or condensation
• Using desiccants in the storage bins
• Avoiding sealed plastic bags that hold moisture
• Maintaining moderate temperatures and not exposing for extended periods of steam or heat

By following these preventive steps, the appearance and surface integrity of tungsten carbide will not only be preserved but also its longevity of operation, especially in harsh applications. Prevention is superior to premature failure of tools or components due to avoidable corrosion.

Part 6. Comparison: Corrosion Resistance of Tungsten Carbide vs. Stainless Steel and Carbon Steel

For easy comparison of the corrosion performance of tungsten carbide, it can be compared with two of the commonly used industrial metals, stainless steel and carbon steel. The two materials and their comparison are provided below:

Material Type	Rust Susceptibility	Characteristics
Carbon Steel	Easily rusts	Low cost and high strength, but requires anti-rust treatment.
Stainless Steel	Usually does not rust	Contains chromium, which forms a passive layer to protect against oxidation.
Tungsten Carbide	Does not rust itself	Extremely hard and abrasion-resistant; however, binder metals (e.g. cobalt) may corrode.

Tungsten carbide exhibits an outstanding compromise between corrosion resistance and ultimate hardness. Though not fully impervious to environmental deterioration, particularly by corrosion of the binder, its net toughness makes it a material of first choice in the majority of demanding industrial applications.

Part 7. How XYMJ Can Help You in Tungsten Carbide

XYMJ, a competitive manufacturer of tungsten carbide parts, offers complete solutions to your specific industrial needs.

• Customized tungsten carbide parts for specific purposes
• Wear-resistant grades of tungsten carbide for harsh environments
• Surface treatment and precision machining
• Material consultation and technical support

As a mold factory, mining equipment supplier, or end user with stringent requirements on material performance, XYMJ is your reliable partner for high-strength, high-accuracy tungsten carbide parts.

Final Thoughts

Tungsten carbide itself is highly resistant to corrosion, and therefore an extremely fitting material for high-strength, high-precision uses of many types. While the binder phase may be slightly vulnerable to corrosion in certain conditions, this can be effectively countered by wise material selection and appropriate surface treatment techniques.

With suitable precautions, tungsten carbide components can in fact fully meet the anti-corrosion requirements of most industrial conditions.

If you’re looking for corrosion-resistant, high-strength tungsten carbide wear parts, XYMJ Tungsten Carbide Parts Manufacturer is a certified and trusted supplier.

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