INCLUSION RATING IN STEELS AS PER ASTM STANDARDS MUHAMMED LABEEB 13MY06
Jun 19, 2015
INCLUSION RATING IN STEELS AS PER ASTM STANDARDS
MUHAMMED LABEEB
13MY06
INCLUSIONS
▪ Inclusions are non metallic particles embedded in the steel matrix.
▪ Chemical compounds of metals like (Fe, Mn, Al, Si, Ca etc) with non metals (O,
S, N, C, H)
▪ Examples: SiO2,MnO,MgS,Ce2S3,AlN etc…
▪ Properties: An inclusion is a mismatch with the steel matrix. Both may have
different properties resulting in undesired effect.
INCLUSION RATING
▪ Standard reference charts depicting a series of typical inclusion configurations
(size, type, and number) were created for direct comparison with the microscopic
field of view
▪ Rating is done in comparison with the ASTM standard chart. [Designation: E 45]
▪ Inclusions are assigned to a category based on similarities in morphology, that is,
by size, shape, concentration, and distribution, and not necessarily on their
chemical identity
CLASSIFICATION OF INCLUSIONS
▪ Inclusions are classified into four categories (called Type) based on their
morphology
▪ Each of them are classified into two subcategories based on their width or
diameter
CLASSIFICATION OF INCLUSIONS
categories
A-Sulfide Type
heavy
thin
B-Alumina Type
heavy
thin
C-Silicate Type
heavy
thin
D-Globular Oxide Type
heavy
thin
• Although the categories contain chemical names that imply knowledge of their chemical content, the ratings are based strictly on morphology
• The four categories, or Types, are partitioned into Severity Levels based on the number or length of the particles present in a 0.50 mm2 field of view
CLASSIFICATION OF INCLUSIONS
▪ Type A and C inclusions are very similar in size and shape
▪ They are distinguished based on their colour when viewed under brightfield illumination
▪ Type A-Sulfide are light gray
▪ Type C-Silicate are black
▪ The B-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
▪ The D-type are globular in shape
PROCEDURE
▪ The minimum polished surface area of a specimen for the microscopic
determination of inclusion content is 160 mm2 (0.25 in.2)
▪ Field of view is 0.50 mm2 or square of side 0.71 mm
▪ Either of two techniques may be employed to achieve a
0.50 mm2 field of view
▪ One method is to project the microscope image onto a viewing screen that has a
square mask with 71.0 mm sides drawn on it
▪ Another option is to use a reticle made for the microscope, which will superimpose the
required square mask directly onto the field of view
PROCEDURE
▪ Inclusions are classified into the before mentioned four types
▪ After the inclusions are categorized by Type, they must be categorized by thickness
or diameter- thin and heavy series
▪ After classification by type and thickness, the severity levels are determined for the
inclusions comparing with the chart
▪ These values can be numerically calculated as length or number based on the
limits given in standard Table (given below)
COMPARISON CHART- A (Sulfide type)
COMPARISON CHART- B (Aluminate type)
COMPARISON CHART- C (Silicate type)
COMPARISON CHART- D (Globular type oxides)
PROCEDURE
REFERENCES
▪ R E SMALLMAN – Modern Physical Metallurgy and Materials Engineering
▪ P C ANGELO – Materials Characterization
▪ ASTM E 45 – 05 - Standard Test Methods for Determining the Inclusion Content
of Steel
▪ ASTM E 1245 - Practice for Determining Inclusion or Second-Phase Constituent
Content of Metals by Automatic Image Analysis