For detailed information, check the Standard ISO 4967 Steel - Determination of content of non-metallic inclusions - Micrographic method using standard diagrams.

This standard is equivalent to ISO 4967 with the exception of slightly different class limits.

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 2 Principles, 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.

The NMI Analysis module provides the following test methods:

  • Method A - Worst fields
  • Method B - Field assessment

Setup

Basic parameter

Measurement area

200 mm2

Total magnification

100x

Measuring field size

0.5 mm2

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 and Ds (fine and thick) for each severity from 0 to 3 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 B - Field assessment

This method evaluates steel specimens with a low inclusion content. The total number of fields of each inclusion type A, B, C, D, Ds (fine and thick) per severity level are reported. The NMI Analysis module calculates for each standard measuring field the index number from 0 to 3 in whole or half-index number increments. For this method, the NMI Analysis module considers contiguous fields located on the grid of standard measuring fields.

For more information on ISO 4967, see ISO 4967.