How does grain size affect the performance of carbide?
The grain size of tungsten carbide has a direct impact on the performance of the finished tool. From service life and toughness to wear resistance and coating compatibility, selecting the right grain structure is key to achieving optimal results. In this article, we’ll explain what grain size actually means, the different types that exist, how it influences material properties and, more importantly, which grain size best suits your specific application. That way, you can choose the right material with confidence.
What exactly is grain size in carbide?
Carbide is made by mixing carbide powder (usually tungsten carbide) with a binder (usually cobalt). The size of the tungsten carbide grains also influences the structure and properties of the material.
The grain size is measured in micrometres (µm). Depending on this size, it is sometimes expressed as one of the following types of grains:
- Ultra-fine grain
- Submicron
- Fine grain
- Medium grain
- Coarse grain
Since there is no fixed definition of a particular grain type, at GSE Carbide we report grain size in micrometres. For instance, our GSE10 carbide has a grain size of 0.8 µm.
How does grain size affect the properties of carbide?
The grain size has a strong influence on the properties of carbide. It determines the balance between hardness and toughness, two properties that usually cannot be maximised simultaneously.
Smaller grain
Larger grain
A larger grain increases the toughness and bending strength of the carbide. This makes it more resistant to fracture and therefore suitable for dynamic loads or operations involving impact.
Grain size and cobalt concentration
While grain size and cobalt content are separate factors, they work together to influence carbide performance.
- Cobalt concentration largely determines the material’s toughness and flexural strength. Higher cobalt content therefore increases toughness but reduces hardness.
- Grain size primarily affects hardness and wear resistance.
By combining the right grain size with the desired cobalt concentration, the end product can achieve optimal performance for your application.
Which grain size is best suited to your application?
When selecting carbide for your application, it is important to understand that the entire carbide grade determines performance, not just the grain size. Properties such as cobalt concentration, density, toughness and hardness work together with the grain structure. Therefore, the final choice is always tailored to both the type of machining operation and the material being machined.
Nevertheless, in practice we see a number of regular patterns recurring in the choice of grain sizes. These are mainly related to the difference between rough machining and finishing:
- Finer grains (ultrafine and submicron) are often used for precise finishes and applications where wear resistance and dimensional accuracy are important. Examples include the use of tools for machining hardened steel in the medical sector or for precision machining in the aviation industry.
- Coarser grains (medium and coarse) offer greater toughness and are therefore better suited to heavier or interrupted machining operations, such as rough machining of cast iron or machining non-ferrous metals in the automotive industry.
GSE Carbide specialises in the correct grain selection
At GSE Carbide we understand that the right grain size makes all the difference. That is why, with over 20 years of experience, we offer a wide range of carbide rods based on different grain sizes and cobalt contents. A large number of fixed lengths and long rods are available from stock as standard. Special compositions are available on request.
To further support your production process, we can also pre-machine our rods in our own grinding shop. By using our CNC grinding service, all you need to do is grind the geometry.
Would you like advice on the right type of carbide for your application? Please contact our specialists, we are happy to assist you.
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