For detailed information, check the Standard ASTM E45:2025 Standard Test Methods for Determining the Inclusion Content of Steel.

The ASTM E45 standard covers a number of test methods for determining the non-metallic inclusion content of wrought steel.

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 11 Classification of Inclusions and Calculation of Severities, here section 11.5, here Table 1 and 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 arrangements of the inclusions, this standard defines the following inclusion types.

• Inclusion type A (sulfide inclusion type)
• Elongated sulfide, very similar to group C. Light gray when viewed under brightfield illumination.
• Inclusion type B (aluminia inclusion type)
• Stringers consist of a number (at least three) of round or angular oxide particles with aspect ratios less than 2 that are aligned nearly parallel to the deformation axis.
• Inclusion type C (silicate inclusion type)
• Very similar to group A. Black when viewed under brightfield illumination. The stringers consist of one or more highly elongated oxides with smooth surfaces aligned parallel to the deformation axis.
• Inclusion type D (oxide inclusion type)
• Any oxides that have aspect ratios < 2, and are not part of an inclusion type B- or an inclusion type C stringer, are rated as inclusion type D. No other shape restriction is applicable. The criterion for this inclusion type is the number of oxides rather than their length.
• Inclusion types Ds and Dos: Ds are globular, gray type D inclusions. Dos are globular, gray and black type D inclusions. In Dos inclusions, the black area portion is larger than the gray area portion.

NMI Analysis provides the following test methods:

• Method A - Worst Fields
• Method D - Low Inclusion Content
• Method E - SAM Rating

Method A - Worst Fields

This method reports the worst fields with the largest severity values per inclusion type. The worst field has the size of a standard measuring field and is located within the measurement area. According to the standard, the worst field can be located anywhere on the specimen and is usually not located on the grid of standard measuring fields. The NMI Analysis module calculates these true worst fields.

The NMI Analysis module reports for each inclusion type A, B, C, D, Ds and Dos (thin and heavy) for each severity from 0 to 5 in half-severity level increments.

Note that fields with inclusions below the smallest severity level (0.5) are not rated and indicated in the Field Statistics tool of the Field Based Inspection view as non-ratable. Empty fields without a specific inclusion type are presented as n.a. for this inclusion type.

Method D - Low Inclusion Content

This method evaluates steel specimens with a low inclusion content. The total number of fields of each inclusion type A, B, C, D, Ds and Dos (thin and heavy) per severity level are reported. The NMI Analysis module calculates for each standard measuring field the severity level from 0 to 5 in whole or half-severity level increments. For this method, the NMI Analysis module considers contiguous fields located on the grid of standard measuring fields.

Method E - SAM Rating

This method rates the inclusion content in a manner that reflects the severity and frequency of occurrence of the larger Type B and D inclusions. The method reports two measures describing the content of type B (thin and heavy) and inclusion type D (heavy) inclusions.

The number of type B fields recorded at each severity level multiplied by the severity level is summed and normalized by dividing by the total measurement area, in square inches. The NMI Analysis module records the nearest whole number as the rating. The number of D units is summed and normalized by dividing by the total rated area, in square inches. The NMI Analysis module reports all oversized inclusion types B and D along with their actual lengths or widths, or both. For more information, see the calculation of method E in the standard document.