Magnetic saturation is a precise and sensitive indicator of cobalt binder condition and carbon balance in WC–Co hardmetals.
At Langsun Carbide, magnetic saturation testing is used to verify that the cobalt binder phase and carbon content in each tungsten carbide grade are within the designed ranges, ensuring consistent hardness, toughness and corrosion behaviour.
Magnetic Saturation Testing Method
Magnetic saturation is measured using a dedicated magnetic saturation analyzer:
1.The cemented carbide sample is placed in a strong magnetic field until the cobalt binder reaches magnetic saturation.
2.The magnetization is measured and then normalized by the sample mass (i.e., specific saturation magnetization).
3.The result is compared against the theoretical saturation value of pure cobalt and the expected value for the specific grade.
A significant deviation from the expected saturation level indicates potential issues with cobinder ntent, carbon content, or the presence of impurity phases.
The Role of Magnetic Saturation in WC–Co Quality Control
Magnetic saturation is especially important for controlling the following:
● Cobalt Content — Confirms the binder content matches the designed grade composition, which directly affects toughness and hardness.
● Carbon Balance — Detects conditions that lead to η-phase formation (carbon deficiency) or free carbon (excess carbon), both of which can reduce performance.
● Binder Purity — Identifies impurities or changes in the binder phase that can affect magnetic properties and mechanical behavior.
When combined with coercivity, hardness, density, and metallographic analysis, magnetic saturation provides a comprehensive picture of the internal condition of WC–Co materials.
Magnetic Saturation Control at Langsun Carbide
Magnetic saturation is integrated into our standard quality routines for WC–Co grades:
● Grade-Specific Saturation Ranges — Each WC–Co grade is assigned a target magnetic saturation range that corresponds to the correct cobalt content and carbon balance.
● Routine Batch Testing — Production batches are tested to confirm saturation values remain within the specified range.
● Integrated Microstructure Evaluation — We interpret saturation results together with metallographic analysis to detect η-phase or free carbon.
● Process Stability — If saturation values drift, we investigate powder chemistry, the sintering atmosphere, and heat-treatment processes to maintain stable microstructure and performance.
By tightly monitoring magnetic saturation, Langsun Carbide ensures every batch of tungsten carbide products delivers highly consistent binder condition and performance.
Typical Magnetic Saturation Data for Common WC–Co Grades
The table below presents indicative cobalt content and magnetic saturation ranges for several common WC–Co compositions used in our product portfolio.
|
Grade |
wCo/% |
wWC/% |
Specific Magnetic Saturation / % of Pure Co |
Interpretation |
|
WC-6Co |
6 |
94 |
5.4 – 5.9 |
Low binder content; high hardness and wear resistance; suitable for severe abrasion. |
|
WC-11.5Co |
11.5 |
88.5 |
9.8 – 10.8 |
Balanced hardness and toughness; widely used for general wear parts and tools. |
|
WC-15Co |
15 |
85 |
12.0 – 13.2 |
Higher binder content; improved toughness and impact resistance for demanding applications. |
Note: Magnetic saturation ranges are typical reference values. Final specifications are defined according to grade design and application requirements.