ASTM B797-93(2002)e1

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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e1
Designation: B 797 – 93 (Reapproved 2002)
Standard Test Method for
Surface Finger Oxide Penetration Depth and Presence of
Interparticle Oxide Networks in Powder Forged (P/F) Steel
Parts
This standard is issued under the fixed designation B 797; 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 (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Sections 1.1, 3.2, 5.1, 6.2, and 8.3 were editorially updated in January 2003.
1. Scope 4.3 For interparticle oxide network concentration, the pol-
ished and unetched sample is examined microscopically at a
1.1 This test method covers a metallographic method for
magnification of 200 to 4003 to determine the presence of
determining the maximum depth of surface finger oxide
interparticle oxide networks.
penetration and the concentration of subsurface interparticle
oxide networks in critical areas of powder forged steel parts.
5. Significance and Use
1.2 This standard does not purport to address all of the
5.1 The presence of surface finger oxide penetration and
safety concerns, if any, associated with its use. It is the
interparticle oxide networks are two of the properties used to
responsibility of the user of this standard to establish appro-
evaluate powder forged steel parts for proper processing.
priate safety and health practices and determine the applica-
Maximum acceptable depths of penetration of surface finger
bility of regulatory limitations prior to use.
oxide penetration and acceptable concentrations of subsurface
2. Referenced Document interparticle oxide networks depend on the component and its
service environment.
2.1 ASTM Standards:
5.2 Results of tests may be used to qualify parts for
E 3 Guide for Preparation of Metallographic Specimens
shipment.
3. Terminology
6. Apparatus
3.1 surface finger oxides—surface finger oxides are surface
6.1 Equipment for the metallographic preparation of test
oxides that follow prior particle boundaries into a powder
specimens.
forged part from the surface and cannot be removed by
6.2 A metallographic microscope permitting observation
physical means such as rotary tumbling. Examples of surface
and measurement up to a magnification of 4003.
finger oxides are shown in Fig. 1.
3.2 interparticle oxide networks—interparticle oxide net-
7. Sampling
works are continuous or discontinuous oxides that follow prior
7.1 A metallographic specimen shall be removed from the
particle boundaries in powder forged parts. Examples of
powder forged part to cover each designated critical area.
interparticle oxide networks are shown in Fig. 2.
Critical areas shall be defined by the applicable part drawing or
4. Summary of Test Method the purchaser order. Specimens shall be taken from the powder
forged part in the condition in which it is to be supplied. The
4.1 A section representing both surface and subsurface
polished surface of the specimens shall be parallel to the
regions of a critical area is cut from the powder forged part and
forging direction, that is, parallel to the direction of travel of
mounted for metallographic grinding and polishing.
the forging punch.
4.2 For surface finger oxide penetration, the polished and
unetched sample is examined microscopically at a magnifica-
8. Procedure
tion of 4003. The maximum depth of penetration of surface
8.1 Preparation of Specimens—In mounting the specimen
finger oxides is measured.
for grinding and polishing, protection from rounding the edge
of the part is essential. In polishing the specimen it is important
This test method is under the jurisdiction of ASTM Committee B09 on Metal
that a clean polish be obtained and that edge detail of the part
Powders and Metal Powder Products and is the direct responsibility of Subcom-
not be destroyed. Specimens shall be examined in the as-
mittee B09.11on Near Full Density Powder Metallurgy
...