Inclusion Rating

Because the non-metallic inclusion destroys metal matrix's continuity and uniformity, it is easy to concentrate stress, result in the decline of mechanical properties, and early failure of the material. The degree of influence mainly depends on the shape, size, distribution and aggregation state of the inclusion. Therefore, it is important to consider the quantity and distribution of inclusions when assessing the quality of steel.

STEMart can carry out inclusion rating on steel according to ISO, ASTM, and other standards.

Test Capabilities

• Oxides: FeO, Fe₂O₃, MnO, SiO₂, Al₂O₃, MgO, Cu₂O, etc.
• Sulfides: FeS, MnS, CaS, etc.
• Silicates: 2FeOSiO₂, 2MnO.SiO₂, CaO.SiO₂, etc.
• Nitrides: TiN, ZrN, VN, etc.

Test Methods

• Combination of metallographic method and micro-area component analysis

After the undetermined inclusions were chosen in the metallographic observation, the micro-area composition analysis was conducted with the Electron Probe Micro-analyzer (EPMA) or the Scanning Electron Microscope (SEM). Energy Dispersive X-ray Spectroscopy (EDS) was used for the composition analysis. It is usually possible to identify the constituent elements and approximate components of inclusions whose size is larger than 1μm, and more logical findings can be obtained if the surface scanning of individual elements is employed.

• Optical metallographic method

The color, shape, size and distribution of the inclusion are observed in the bright field of view under the optical microscope to identify the type of inclusion. The natural color and transparency of the inclusion are observed in the dark field, and inclusion's various optical properties are observed under the opposite polarized light. The corresponding grade is evaluated according to the distribution and quantity of inclusions, and its impact on the properties of steel is assessed.

For more information about our inclusion rating services, please contact us.