ASTM B796-14
(Test Method)Standard Test Method for Nonmetallic Inclusion Content of Ferrous Powders Intended for Powder Forging (PF) Applications
Standard Test Method for Nonmetallic Inclusion Content of Ferrous Powders Intended for Powder Forging (PF) Applications
SIGNIFICANCE AND USE
4.1 The extensive porosity present in pressed and sintered ferrous materials masks the effect of inclusions on mechanical properties. In contrast, the properties of material powder forged to near full density are strongly influenced by the composition, size, size distribution, and location of nonmetallic inclusions.
4.2 The test for nonmetallic inclusions in powder forged steels is useful as the following:
4.2.1 Characteristic to classify or differentiate one grade of powder from another.
4.2.2 Means of quality comparison of powders intended for powder forging, lot to lot.
4.3 Significant variations in nonmetallic inclusion content will occur if:
4.3.1 The powder used to form the test specimen does not meet powder forging quality standards for nonmetallic inclusion content.
4.3.2 Processing of the powder forged test specimen has been carried out under conditions that do not permit oxide reduction or allow oxidation of the test specimen, or both.
SCOPE
1.1 This test method covers a metallographic method for determining the nonmetallic inclusion level of ferrous powders intended for powder forging (PF) applications.
1.2 The test method covers repress powder forged test specimens in which there has been minimal lateral material flow (
1.3 This test method is not suitable for determining the nonmetallic inclusion level of powder forged test specimens that have been forged such that the core region contains porosity. At the magnification used for this test method residual porosity is hard to distinguish from oxide inclusions. Too much residual porosity makes a meaningful assessment of the inclusion population impossible.
1.4 The test method may be applied to materials that contain manganese sulfide (admixed or prealloyed) provided the near neighbor separation distance is changed from 30 μm to 15 μm.
Note 1: The test method may be applied to powder forged parts where there has been a greater amount of material flow provided:
The near neighbor separation distance is changed, or
The inclusion sizes agreed between the parties are adjusted for the amount of material flow.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Buy Standard
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: B796 − 14
Standard Test Method for
Nonmetallic Inclusion Content of Ferrous Powders Intended
1
for Powder Forging (PF) Applications
This standard is issued under the fixed designation B796; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 2. Referenced Documents
2
1.1 This test method covers a metallographic method for 2.1 ASTM Standards:
determiningthenonmetallicinclusionlevelofferrouspowders E3Guide for Preparation of Metallographic Specimens
intended for powder forging (PF) applications. E768Guide for Preparing and Evaluating Specimens for
Automatic Inclusion Assessment of Steel
1.2 The test method covers repress powder forged test
specimens in which there has been minimal lateral material
3. Summary of Test Method
flow (<1%). The core region of the powder forged test
3.1 A section representing the core region is cut from the
specimen shall contain no porosity detectable at 100×.
powder forged test specimen, parallel to the direction of
1.3 This test method is not suitable for determining the
forging, to obtain a rectangular section that is mounted for
nonmetallic inclusion level of powder forged test specimens
metallographic grinding and polishing.
that have been forged such that the core region contains
3.2 The polished sample is examined microscopically at a
porosity.Atthemagnificationusedforthistestmethodresidual
magnification of 100× and a note made of inclusions larger
porosityishardtodistinguishfromoxideinclusions.Toomuch
than a predetermined size.
residual porosity makes a meaningful assessment of the inclu-
3.3 The maximum Feret’s diameter is used to determine
sion population impossible.
inclusion size. A Feret’s diameter is a caliper diameter as
1.4 Thetestmethodmaybeappliedtomaterialsthatcontain
illustrated in Fig. 1.
manganese sulfide (admixed or prealloyed) provided the near
neighbor separation distance is changed from 30 µm to 15 µm. 3.4 The fragmented nature of some inclusions means that
theirsizedeterminationissomewhatcomplicated.Theconcept
NOTE1—Thetestmethodmaybeappliedtopowderforgedpartswhere
of near neighbor separation is used in determining inclusion
there has been a greater amount of material flow provided:
size. If an inclusion is within a certain distance of its neigh-
The near neighbor separation distance is changed, or
The inclusion sizes agreed between the parties are adjusted for the
boring particles, it is considered a member of an inclusion
amount of material flow.
cluster or agglomerate. Detected features within 30 µm of one
1.5 The values stated in SI units are to be regarded as another are considered part of the same inclusion.The concept
standard. No other units of measurement are included in this is illustrated schematically in Fig. 2.
standard.
3.5 The nonmetallic inclusion level of the test specimen is
2
1.6 This standard does not purport to address all of the
reported as the number of inclusions per 100 mm greater than
safety concerns, if any, associated with its use. It is the or equal to the predetermined size.
responsibility of the user of this standard to establish appro-
4. Significance and Use
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 4.1 The extensive porosity present in pressed and sintered
ferrous materials masks the effect of inclusions on mechanical
properties.Incontrast,thepropertiesofmaterialpowderforged
1
This test method is under the jurisdiction of ASTM Committee B09 on Metal
Powders and Metal Powder Products and is the direct responsibility of Subcom-
2
mittee B09.11 on Near Full Density Powder Metallurgy Materials. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Sept. 1, 2014. Published October 2014. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1988. Last previous edition approved in 2002 as B796–07. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/B0796-14.
the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
B796 − 14
determines the features that will be resolved, and all detected features are
included in the assessment of inclusion size.
6. Test Specimen Preparation
6.1 Mix the powder that is intended for use in a powder
forgingapplicationwithanappropriateamountofgraphiteand
lubricant.
6.2 Press a cylindrical compa
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B796 − 07 B796 − 14
Standard Test Method for
Nonmetallic Inclusion Content of Ferrous Powders Intended
1
for Powder Forging (PF) Applications
This standard is issued under the fixed designation B796; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers a metallographic method for determining the nonmetallic inclusion level of ferrous powders
intended for powder forging (PF) applications.
1.2 The test method covers repress powder forged test specimens in which there has been minimal lateral material flow (< 1%).
The core region of the powder forged test specimen shall contain no porosity detectable at 100×.
1.3 This test method is not suitable for determining the nonmetallic inclusion level of powder forged test specimens that have
been forged such that the core region contains porosity. At the magnification used for this test method residual porosity is hard to
distinguish from oxide inclusions. Too much residual porosity makes a meaningful assessment of the inclusion population
impossible.
1.4 The test method may be applied to materials that contain manganese sulfide (admixed or prealloyed) provided the near
neighbor separation distance is changed from 30 μm to 15 μm.
NOTE 1—The test method may be applied to powder forged parts where there has been a greater amount of material flow provided:
The near neighbor separation distance is changed, or
The inclusion sizes agreed between the parties are adjusted for the amount of material flow.
NOTE 1—The test method may be applied to powder forged parts where there has been a greater amount of material flow provided:
The near neighbor separation distance is changed, or
The inclusion sizes agreed between the parties are adjusted for the amount of material flow.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
E3 Guide for Preparation of Metallographic Specimens
E768 Guide for Preparing and Evaluating Specimens for Automatic Inclusion Assessment of Steel
3. Summary of Test Method
3.1 A section representing the core region is cut from the powder forged test specimen and specimen, parallel to the direction
of forging, to obtain a rectangular section that is mounted for metallographic grinding and polishing.
3.2 The polished sample is examined microscopically at a magnification of 100× and a note made of inclusions larger than a
predetermined size.
3.3 The maximum Feret’s diameter is used to determine inclusion size. A Feret’s diameter is a caliper diameter as illustrated
in Fig. 1.
1
This test method is under the jurisdiction of ASTM Committee B09 on Metal Powders and Metal Powder Products and is the direct responsibility of Subcommittee B09.11
on Near Full Density Powder Metallurgy Materials.
Current edition approved Oct. 1, 2007Sept. 1, 2014. Published November 2007October 2014. Originally approved in 1988. Last previous edition approved in 2002 as
B796 – 02.B796 – 07. DOI: 10.1520/B0796-07.10.1520/B0796-14.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
B796 − 14
FIG. 1 Schematic illustration of Feret’s diameter.
3.4 The fragmented nature of some inclusions means that their size determination is somewhat complicated. The concept of near
neighbor separation is used in determining inclusion size. If an inclusion is within a certain distance of its neighboring particles,
it is considered a member of an inclusion cluster or agglomerate. Detected features within 30 μm of one another are considered
part of the same in
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.