Standard Test Method for
Metallographically Estimating the Observed Case Depth of
Ferrous Powder Metallurgy (P/M) Parts1
This standard is issued under the fixed designation B 931; 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.
1. Scope
1.1 A metallographic method is described for estimating the
observed case depth of ferrous powder metallurgy (P/M) parts.
This method may be used for all types of hardened cases where
there is a discernible difference between the microstructure of
the hardened surface and that of the interior of the part.
1.2 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
2.1 ASTM Standards:
B 243 Terminology of Powder Metallurgy2
E 407 Practice for Microetching Metals and Alloys3
3. Terminology
3.1 Definitions—Definitions of powder metallurgy (P/M)
terms can be found in Terminology B 243.
Additional descriptive information is available in the Related Material section of
Vol 02.05 of the Annual Book of ASTM Standards.
3.2 The metallographically estimated observed case depth is
defined as the distance from the surface of the part to the point
where, at a magnification of 100X, there is a discernible
difference in the microstucture of the material.
4. Summary of Test Method
4.1 The powder metallurgy part is sectioned and the surface
prepared for metallographic evaluation.
The metallographic specimen is etched and the distance is measured from the
surface of the part to the point at which a discernible difference
in the microstructure of the material is observed.
5. Significance and Use
5.1 The engineering function of many P/M parts may
require an exterior portion of the part to have a hardened layer
Click below to download Astm B 931 – 03 Pdf free
[wpdm_package id=’6167′]
Click here to Astm B 930 – 03 Pdf free download