The following table gives a brief overview of methods K and M concerning SEP 1571 and comparable standards.

Source: SEP 1571 Part 1:2017-08: Evaluation of inclusions in special steels based on their surface areas – Part 1: Basics, Verlag Stahleisen GmbH, Düsseldorf 2017, Table 3: Comparison between the SEP 1571 method K and M and comparable test specifications, page 28.
* Comparison is also valid for ASTM E45 because no basic definitions have been changed with the standard revision from ASTM E45a:2018 to ASTM E45:2025.

SEP 1571

DIN EN 10247
2007

ISO 4967
2013

ASTM E45:
2025

DIN 50602
1985

Results cannot be influenced by change of category (thin/heavy)

Results cannot be influenced by change of category (thin/heavy)

Shifting of marginal thin (thin) inclusions towards thick (heavy) is possible

Shifting of marginal thin (thin) inclusions towards thick (heavy) is possible

Results cannot be influenced by change of category (thin/heavy)

Free path proximity conditions in and transverse to the rolling direction

Free path proximity conditions in and transverse to the rolling direction

Free path proximity conditions in and transverse to the rolling direction

Distance 40 μm in rolling direction and 15 μm transverse to them, likely similar to ISO 4967.

Proximity condition relative to the inclusion size; direction of distance is undefined

Definition of a smallest particle for forming lines of 5 μm²

Smallest particle 2 μm x 3 μm

Not available

According to chapter 11.4 inclusions thinner than 2 μm are not considered in the degree of severity.

Not available

Globular when l/b < 2.0

Globular when l/w < 3.0

Globular when l/b < 3.0

Globular when l/b < 2.0

Globular is not defined

No evaluation limits (g < 0, g > 9 possible)

Evaluation range is limited, optionally expandable upwards

Evaluation range is unlimited upwards (Annex D1)

Evaluation range is expandable upwards (> 3)

Restricted evaluation limits from K0 to K9

Uniform evaluation criteria for all inclusion types: surface

Uniform evaluation criteria for all inclusion types: surface area or length or number

Different evaluation depending on the inclusion type (length, thickness, number)

Different evaluation depending on the inclusion type (length, thickness, number)

Uniform evaluation criteria for all inclusion types: surface

Oversized (not classifiable) types are not available, since an extension of the class limits is possible

Oversized is possible, in current revision without a defined measure (In the revision of 2017 the following applies: Oversized only for excess lengths: they have to be evaluated as the next lower class and noted separately.)

Oversized is possible, separately noted

Oversized is possible, separately noted outside of the standard value table

Oversized are considered as macro-inclusions