Will tungsten carbide products become brittle when heated to 400 degrees？Why？

Tungsten carbide products, like most materials, undergo changes in properties when exposed to elevated temperatures. While tungsten carbide is known for its exceptional hardness and wear resistance, it can become brittle at high temperatures, especially when exceeding certain critical temperatures. The reasons for this behavior are related to the material's thermal and mechanical characteristics:

1. Cobalt Binder Phase:

Tungsten carbide is often bound together with a binder phase, commonly cobalt. At elevated temperatures, cobalt has a tendency to undergo a phase transformation, which can reduce the material's ductility and impact toughness. This transformation is often referred to as the "cobalt binder embrittlement."

2. Thermal Expansion Mismatch:

Tungsten carbide and cobalt have different coefficients of thermal expansion. When heated, this thermal expansion mismatch can create internal stresses within the material, potentially leading to cracking and reduced toughness.

3. Decarburization:

At high temperatures, there is a risk of decarburization, which involves the loss of carbon from the tungsten carbide structure. The reduction in carbon content can compromise the hardness and wear resistance of the material.

4. Recrystallization:

Tungsten carbide undergoes recrystallization at elevated temperatures, resulting in changes to the grain structure. This can affect the mechanical properties of the material, including hardness and brittleness.

5. Oxidation:

Exposure to elevated temperatures in the presence of oxygen can lead to oxidation of the tungsten carbide surface. Oxidation can introduce surface flaws and reduce the material's overall performance.

The critical temperature at which tungsten carbide becomes brittle depends on various factors, including the specific composition of the tungsten carbide (such as the ratio of tungsten to cobalt), the nature of the application, and the duration of exposure to high temperatures.

For many grades of tungsten carbide, significant changes in properties, including increased brittleness, can occur at temperatures around 400 degrees Celsius (752 degrees Fahrenheit) and higher. Therefore, it is essential to consider the operating temperature limits when using tungsten carbide products, especially in applications involving high-temperature environments.

If thermal stability is a crucial consideration for an application, alternative materials or coatings may be explored that better withstand elevated temperatures without compromising mechanical properties. Always refer to the specific recommendations and specifications provided by the manufacturer for the tungsten carbide product in question.