For detailed information, check the Standard DIN EN 10247 Micrographic examination of the non-metallic inclusion content of steels using standard pictures.

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 and/or number, see the Standard in chapter 10, table 2. 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 the arrangement, this standard defines the following inclusion types.

  • Inclusion type α
  • Elongated, scattered
  • Inclusion type γ
  • Elongated, aligned
  • Inclusion type β
  • Globular, aligned
  • Inclusion type
  • Globular, scattered

Additionally, the inclusions are classified according to their color.

  • Inclusion type α
  • Gray (EA), black (EC) or color (EFC)
  • Inclusion type γ
  • Gray (EA), black (EC) or color (EFC)
  • Inclusion type β
  • Gray (EAB), black (EB) or color (EFB)
  • Inclusion type
  • Gray (EAD), black (ED) or color (EFD)

The NMI Analysis module provides the following test methods:

  • Method P - Largest inclusion
  • Method M - Largest field
  • Method K - Mean inclusion content

Setup

Basic parameter

Measurement area

200 µm2

Total magnification

100 x

Measuring field size

0.5 mm2

Method P - Largest inclusion

For each type of inclusion, only the inclusion having the greatest value of the selected method parameter L, d or a is evaluated and recorded. The result of the evaluation is the average of the individual values of the assessed specimens.

The measured size values are related to and reported as standardized size values based on the size classification in rows (q) and columns (k), seetable 2 in the standard. The NMI Analysis module reports the largest inclusion length (L), diameter (d), area (a) per type for rating according to method PL, Pd and Pa.

Method M - Largest field

For each inclusion type, the largest field is determined for the method parameter: inclusion number (n), length (L), diameter (d), area (a). The largest field has the size of a standard measuring field and can be located anywhere within the measurement area ("True worst field"). The NMI Analysis module calculates the total values per field and reports the characteristic values Mn, ML, Md, Ma according to method M per inclusion type. The measured size values are related to and reported as standardized size values based on the size classification in rows (q) and columns (k), see table 2 in the standard. The result of the evaluation is the average of the individual values of the assessed specimens.

Method K - Mean inclusion content

For each inclusion type, the mean inclusion content of the measurement area is determined based on the method parameter: inclusion number (n), length (L), diameter (d), area (a). The NMI Analysis module calculates the total values and reports the characteristic values Kn, KL, Kd, Ka according to method K per inclusion type. The measured size values are related to and reported as standardized size values based on the size classification in rows (q) and columns (k), see table 2 in the standard.

The K value can be calculated in the following way:

  • for number (Kn), or number and length (Kn, KL), or number and area (Kn, Ka) for elongated inclusions;
  • for number (Kn), or number and diameter (Kn, Kd), or number and area (Kn, Ka) for globular inclusions.

The total number of assessed fields Nj is counted, including empty fields.