For detailed information, check the Standard DIN 50602 Metallographie test methods; microscopic examination of special steels using standard diagrams to assess the content of non-metallic inclusions.

This standard specifies the examination of non-metallic inclusions in special steels.

The NMI Analysis module generates a report document showing the method results and corresponding characteristic values.

Inclusion assessment

For information on the inclusion classification by size, see the Standard in chapter 6, tables 2 and table 3. To obtain a reasonable evaluation of the inclusion distribution within a lot, at least six locations, chosen to be as representative of the lot as possible, should be examined.

Inclusion categories

According to the shape and arrangement of the inclusions, this standard defines the following inclusion types.

• Inclusion type SS (sulfide inclusion type)
• Sulfide inclusions of elongated type, gray particles.
• Inclusion type OA (aluminium oxide inclusion type)
• Oxide inclusions, black particles of aligned type.
• Inclusion type OS (silicate inclusion type)
• Oxide inclusions of elongated type, dark-gray, black particles.
• Inclusion type OG (globular oxide inclusion type)
• Oxide inclusions of globular type, black, isolated particles.

The NMI Analysis moduleNMI Analysis provides the following test methods:

• Method M - Maximum inclusion value
• Method K - Mean inclusion value

Methode M

The NMI Analysis module evaluates the field with the largest inclusion for each type and specimen. The result is the sum of these maximum rating values divided by the number of the examined specimen.

Method K

The NMI Analysis module evaluates the non-metallic inclusions separately for the individual inclusion types. The frequency of each size class is recorded. To determine the inclusion content, the individual frequencies are multiplied by a factor so that larger inclusions are weighted more heavily than smaller inclusions. Depending on the agreement, the summation or the reporting respectively begins with a certain size class, e.g. only inclusions of sizes 4 (method K4) and greater are considered.