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  • Inclusion Rating

    Because the non-metallic inclusion destroys the continuity and uniformity of the metal matrix, it is easy to cause stress concentration, cause the decline of mechanical properties, and lead to the early failure of the material. The degree of influence mainly depends on the shape, size, distribution and aggregation state of the inclusion. Therefore, the quantity and distribution of inclusions are important indicators to evaluate the quality of steel. For metallographic analysts, how to correctly judge and identify non-metallic inclusions has become very important. As a professional reliability third-party testing organization, T,C&A Lab can perform inclusion rating analysis and testing on steel according to ISO, ASTM and other standards. Welcome to contact our experts for consultation.

    T,C&A Lab's inclusion rating capabilities include:

    • 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.

    The identification methods of inclusions we provide include:

    • Combination of metallographic method and micro-area component analysis

    After the undetermined inclusions were selected in the metallographic observation, the micro-area composition analysis was carried out 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 determine the constituent elements and approximate components of inclusions whose size is larger than 1μm, and more intuitive results can be obtained if the surface scanning of individual elements is used.

    • Optical metallographic method

    The color, shape, size and distribution of the inclusion are observed in the bright field of view under the optical microscope, the inherent color and transparency of the inclusion are observed in the dark field, and the various optical properties of the inclusion are observed under the orthogonal polarized light to judge the type of the inclusion. The corresponding grade is evaluated according to the distribution and quantity of inclusions, and its influence on the properties of steel is evaluated.

    Quantitative rating of non-metallic inclusions

    • JK ratings

    JK standard rating chart is divided into 4 basic types according to the shape and distribution of inclusions. Type A sulfide type, type B alumina type, type C silicate type and type D spherical oxide type. Each type of inclusions is divided into two series, coarse series and fine series, according to their thickness or diameter. Each series is composed of five grades (grades 1 to 5) pictures showing the increasing content of inclusions. When assessing the grade of inclusions, half-grade assessments are allowed, such as 0.5 and 1.5.

    • ASTM ratings

    The ASTM standard rating chart is also called the modified JK chart. The classification and series of inclusions in the rating chart are the same as those of the JK standard chart, but the rating chart consists of five grades of 0.5 to 2.5, which is suitable for evaluating inclusions in high purity steel.

    Standards we test to

    ASTM E45 - 18aStandard Test Methods for Determining the Inclusion Content of Steel
    ASTM E1245Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis
    ISO 3763Wrought Steels - Macroscopic Methods for Assessing the Content of Nonmetallic Inclusions
    ISO 4967Steel - Determination of Content of Nonmetallic Inclusions - Micrographic Methods Using Standard Diagrams

    In addition, the experts in our Inclusion Rating Laboratory also provide a variety of custom services as your needs and requirements. Let's discuss the custom service with our experts for free.

    Instruments and data

    inverted metallurgical microscope
    optical micrographs of oxide and sulfide inclusions
    optical micrographs of globular and oxide inclusions
    optical micrographs of globular oxide inclusions


    1. Arreola-Herrera, R.; et al. The effect of non-metallic inclusions on the mechanical properties of 32 CDV 13 steel and their mechanical stress analysis by numerical simulation[J]. Theoretical & Applied Fracture Mechanics, 2018:S0167844217303877.

    Note: this service is for Research Use Only and Not intended for clinical use.


    T,C & A LAB is an independent lab providing quality or custom testing, characterization and analysis of a variety of materials. Our engaged experts are ready to help you.

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