ASTM B934-04a

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Designation:B934–04a
Standard Test Method for
Effective Case Depth of Ferrous Powder Metallurgy (P/M)
1
Parts Using Microindentation Hardness Measurements
This standard is issued under the fixed designation B934; 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 3.2.1 case —that portion of a part, extending inward from
the surface that has a microindentation hardness, after harden-
1.1 This test method covers a procedure for determination
ing, equal to or greater than a specified hardness.
of the effective case depth of powder metallurgy (P/M) parts.
3.2.2 effective case depth—perpendicular distance from the
1.2 A microindentation hardness traverse procedure is de-
surface of the hardened case to the furthest point where a
scribedtodetermineeffectivecasedepth.Thistestmethodmay
microindentation hardness value equivalent to 50 HRC is
be used to determine the effective case depth for all types of
maintained, unless otherwise specified.
hardened cases.
1.3 The procedure for determining the microindentation
4. Summary of Test Method
hardness of powder metallurgy materials, as described in Test
4.1 The powder metallurgy part is sectioned and the surface
Method B933 shall be followed.
prepared for examination. Microindentation hardness measure-
1.4 This standard does not purport to address all of the
ments are taken at various depths below the part surface. The
safety concerns, if any, associated with its use. It is the
distance where the microindentation hardness falls below the
responsibility of the user of this standard to establish appro-
equivalent of 50 HRC is defined as the effective case depth,
priate safety and health practices and determine the applica-
unless otherwise specified.
bility of regulatory limitations prior to use.
5. Significance and Use
2. Referenced Documents
2 5.1 The engineering function of many P/M parts may
2.1 ASTM Standards:
require an exterior portion of the part to have a specified case
B243 Terminology of Powder Metallurgy
depth and microindentation hardness. Measurement of effec-
B933 Test Method for Microindentation Hardness of Pow-
tive case depth is used to determine the depth to which the
der Metallurgy (PM) Materials
microindentation hardness of the exterior portion of a part has
E384 Test Method for Microindentation Hardness of Mate-
been increased over that of the interior of the part.
rials
6. Apparatus
3. Terminology
6.1 Knoop or Vickers Hardness Indenters, using 100 gf
3.1 Definitions of powder metallurgy (P/M) terms can be
(0.9807 N) loads are recommended following Test Method
found in Terminology B243. Additional descriptive informa-
E384. The type of hardness indenter and load used shall be
tion is available in the Related Material section of Volume
agreed upon between customer and producer.
02.05 of the Annual Book of ASTM Standards.
6.2 Calibrated Optical Instrument, Micrometer Stage,or
3.2 Definitions of Terms Specific to This Standard:
other suitable means to measure the distance from the surface
of the part to the center of the impression with a precision of
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This test method is under the jurisdiction of ASTM Committee B09 on Metal
0.025 mm.
Powders and Metal Powder Products and is the direct responsibility of Subcom-
mittee B09.05 on Structural Parts.
7. Test Specimen
Current edition approved Oct. 1, 2004. Published October 2004. Originally
approved in 2004. Last previous edition approved in 2004 as B934 – 04. DOI: 7.1 Cut a test specimen from the P/M part, perpendicular to
10.1520/B0934-04A.
the hardened surface at a specified location, being careful to
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
avoid any cutting or grinding procedure that would affect the
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
original microindentation hardness.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
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B934–04a
7.2 Mounting of the test specimen is recommended for Randomly encountered upper bainite or fine pearlite in the
convenience in surface preparation, edge retention, and micro- martensite should not be excluded as a measurement location.
indentation hardness measurement. Edge retention is important 8.3 Plot microindentation hardness versus distance from the
for proper depth measurement of the case. part surface (see Fig. 2). The effective case depth shall be the
7.3 Grind and polish the
...