Introduction to Standards
The NMI Analysis module supports the following standards:
|
Standard |
Method |
Short |
Long |
|---|---|---|---|
|
ASTM E45 |
A |
Worst fields |
Fields* with highest severity rating per inclusion type, based on largest total inclusion length per field and further categorization in thin and heavy based on inclusion width. True worst field identification. For more information, see ASTM E45. |
|
ASTM E45 |
D |
Low inclusion content |
For steels with low inclusion content. Number of fields per inclusion type and severity rating. |
|
ASTM E45 |
E |
SAM rating |
Only larger inclusions type of B and D are considered. Number of fields per severity rating for B thin, B heavy, D heavy. Weighted result, SAM rating for type B and D. |
|
ISO 4967 |
A |
Worst fields |
Fields with highest severity rating per inclusion type, based on largest total inclusion length per field and further categorization in fine and thick based on inclusion width. True worst field identification. For more information, see ISO 4967. |
|
ISO 4967 |
B |
Field assessment |
Comparable to ASTM E45, Method D. Total number of fields per inclusion type and severity rating. |
|
JIS G 0555 |
A |
Worst fields |
Revision JIS G 0555:2020 is based on ISO 4967:1998 and revision JIS G 0555:2023 is based on ISO 4967:2013. Worst fields: fields with highest severity rating per inclusion type, based on largest total inclusion length per field and further categorization in fine and thick based on inclusion width. True worst field identification. For more information, see JIS G 0555. |
|
JIS G 0555 |
B |
Field assessment |
Revision JIS G 0555:2020 is based on ISO 4967:1998 and revision JIS G 0555:2023 is based on ISO 4967:2013. Total number of fields per inclusion type and severity rating. |
|
GB/T 10561 |
A |
Worst fields |
Almost identical to ISO 4967:1998 with only small differences in size classification. Worst fields: fields with highest severity rating per inclusion type, based on largest total inclusion length per field and further categorization in fine and thick based on inclusion width. True worst field identification. For more information, see GB/T 10561. |
|
GB/T 10561 |
B |
Field assessment |
Almost identical to ISO 4967:1998 with only small differences in size classification. Total number of fields per inclusion type and severity rating. |
|
(DIN) EN 10247 |
P |
Largest inclusion |
Largest inclusion: inclusions with largest length, diameter, and area per inclusion type. Standardized size values. For more information, see DIN EN 10247. |
|
(DIN) EN 10247 |
M |
Largest field |
Fields with the largest number, total length, diameter, and area per inclusion type. Standardized size values. For more information, see EN 10247, table 2. The largest field is based on the true worst field identification. |
|
(DIN) EN 10247 |
K |
Mean inclusion content |
Mean inclusion content of the analyzed specimen area: inclusion content based on total number, length, diameter, and area per inclusion type. Standardized size values. |
|
SEP 1571 |
M |
Maximum inclusion value |
Largest size class rating per inclusion type based on inclusion area. Single inclusion rating comparable to EN 10247, method P. For more information, see SEP 1571. |
|
SEP 1571 |
K |
Mean inclusion value |
Size weighted and normalized Oxide and Sulfide content of the analyzed specimen area. Number of inclusions per size class and inclusion type. Single inclusion rating based on inclusion area. |
|
DIN 50602 |
M |
Maximum inclusion value |
Withdrawn standard but in practice still in use. Fields with the largest characteristic value per inclusion type. For more information, see DIN 50602 |
|
DIN 50602 |
K |
Mean inclusion value |
Withdrawn standard but in practice still in use. Normalized inclusion content per inclusion type. |
For detailed Information, check the respective standards.
All supported standards are visible in the standard template editor, see Standard Template Editor.
Basic Principles of Inclusion Groupings
The analysis of shape and morphology of individual particles is essential for the grouping into inclusions. For inclusion formation a particle is considered to have a round or elongated shape. The definition of where round is getting elongated depends on the standard. The particle shape in combination with the distance to next neighboring inclusion(s) is decisive for the grouping of single particles to aligned inclusions. Note: The shape definition and the grouping rules differ from standard to standard. Therefore, a direct comparison of standard results on the base of individual inclusions is usually complex.
As a Supervisor, you can copy and edit pre-configured standard templates, see Standard Template Editor.
For detailed information on inclusion inspection with the NMI Analysis module, see NMI Global Results View and NMI Field Based Inspection View
Each standard has its own grouping rules but the underlying principles are comparable and therefore described based on the definitions of EN 10247.
One single inclusion (particle)
Calculation of the nearest neighbor to group inclusions
The nearest neighbor is defined by the distance between the inclusions perpendicular to the main deformation direction (t) and the distance between the inclusions in the main deformation direction (e). If the distance criteria are fulfilled, one stringer is formed and rated as one inclusion. If the distance criteria are not fulfilled, two isolated inclusions are rated.
Formation of Stringers
|
Two particles - one stringer |
Two particles - no stringer |
|
If e ≤ 40 µm and t ≤ 10 µm: |
If e > 40 µm or t > 10 µm: |
If the distance criteria are fullfilled, the two inclusions are combined to one inclusion stringer with two particles. The calculation of the total length and width for the inclusion stringer is shown according to the standard EN 10247 in the Figure above. Note: The calulation might differ depending on the standard and the standard specific inclusion type.
Agglomeration of stringers to group inclusions
|
1 |
Eight particles |
2 |
Eight particles |
|
3 |
16 particles |
Based on the inclusion size calculation all inclusions are classified per type and size for each individual standard. The resulting standard specific ratings are used in the different methods for further calculation and result presentation. The ratings and calculated characteristic values determine the cleanliness of steel.
See also
ASTM E45
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
|
Setup |
Basic parameter |
|---|---|
|
Measurement area |
160 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, 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.
ISO 4967
For detailed information, check the Standard ISO 4967 Steel - Determination of content of non-metallic inclusions - Micrographic method using standard diagrams. This standard is related to ASTM E45.
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, here, table 1 and table 2. To obtain a reasonable estimate of inclusion variations within a lot, at least six locations, chosen to be as representative of the lot as possible, should be examined. 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 A (sulfide inclusion type)
- Highly malleable, individual gray particles with a wide range of aspect ratios (length/width) and generally rounded ends.
- Inclusion type B (aluminate inclusion type)
- Numerous non-deformable, angular, low aspect ratio (generally < 3), black or bluish particles (at least three) aligned in the deformation direction.
- Inclusion type C (silicate inclusion type)
- Highly malleable, individual black or dark gray particles with a wide range of aspect ratios (generally > 3) and generally sharp ends.
- Inclusion type D (globular oxide inclusion type)
- Non-deformable, angular or circular, low aspect ratio (generally < 3), black or bluish, randomly distributed particles.
- Inclusion type DS (single globular inclusion type)
- Circular, or nearly circular, single particle with a diameter > 13 μm.
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.
See also
JIS G 0555
For detailed information, check the Standard JIS G 0555 Microscopic testing methods for the non-metallic inclusions in steel. JIS G 0555: 2020 is based on ISO 4967:1998. JIS G 0555: 2023 is based on ISO 4967:2013.
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 Principle, 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 arrangement of the inclusions, this standard defines the following inclusion types.
- Inclusion type A (sulfide inclusion type)
- Highly malleable, individual gray particles with a wide range of aspect ratios (length/width) and generally rounded ends.
- Inclusion type B (aluminate inclusion type)
- Numerous non-deformable, angular, low aspect ratio (generally < 3), black or bluish particles (at least three) aligned in the deformation direction.
- Inclusion type C (silicate inclusion type)
- Highly malleable, individual black or dark gray particles with a wide range of aspect ratios (generally ≥ 3) and generally sharp ends.
- Inclusion type D (globular oxide inclusion type)
- Non-deformable, angular or circular, low aspect ratio (generally < 3), black or bluish, randomly distributed particles.
- Inclusion type DS (single globular inclusion type)
- Circular, or nearly circular, single particle with a diameter ≥ 13 μm.
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 of the examined specimen. 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.
NMI Analysis reports the number and size of each inclusion type A, B, C, D and Ds (fine and thick) for each index number 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 of the field based inspection 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.
GB/T 10561
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.
DIN EN 10247
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.
SEP 1571
For detailed information, check the Standard SEP 1571 Evaluation of inclusions in special steels based on their surface areas – Part 1: Basics. The scope of testing for methods K and M is described in SEP 1571 Part 2.
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 Annex E. 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 A (sulfide inclusion type)
- Light gray elongated inclusion or stringer, usually MnS.
- Inclusion type B (aluminium or magnesium oxide inclusion type)
- Dark gray to black stringer that consists of at least three non-contiguous, predominantly globular particles, usually aluminum oxides or magnesium oxides.
- Dark gray to black compact, elongated inclusion consisting of at least three contiguous non-deformable particles.
- Inclusion type C (oxide inclusion type)
- Black elongated inclusion or inclusion line that consists of one or more deformable elongated particles, generally a silicate.
- Inclusion type D (aluminium or magnesium oxide inclusion type)
- Dark gray to black globular inclusion, randomly distributed, generally an aluminum oxide or magnesium oxide.
- Inclusion type Dsulf (sulfide inclusion type)
- Gray globular inclusion, randomly distributed, e.g. CaS.
The NMI Analysis module provides the following test methods:
- Method M - Maximum inclusion value
- Method K - Mean inclusion value
|
Setup |
Basic parameter |
|---|---|
|
Measurement area |
200 mm2 |
|
Total magnification |
100x |
|
Measuring field size |
0.5 mm2 |
Method M - Maximum inclusion value
The NMI Analysis module evaluates the largest inclusion of each type for each specimen as described in SEP 1571 - Part 2. The result is the sum of these maximum rating values divided by the number of the examined specimen. Compared to DIN 50602, individual inclusions are inspected instead of a field based evaluation.
Method K - Mean inclusion value
The NMI Analysis module evaluates the non-metallic inclusions separately for the individual inclusion types. The frequency of each size class is recorded as described in SEP 1571 - Part 2. 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 and greater are considered (method K4).
DIN 50602
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.
|
Setup |
Basic parameter |
|---|---|
|
Measurement area |
200 mm2 |
|
Total magnification |
100x |
|
Measured field size |
0.5 mm2 |
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.
|
Setup |
Basic parameter |
|---|---|
|
Measurement area |
min. 100 mm2 |
|
Total magnification |
100x |
|
Measured field size |
0.5 mm2 |