ASTM B934-04

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
Designation:B934–04
Standard Test Method for
Effective Case Depth of Ferrous Powder Metallurgy (P/M)
Parts Using Microindentation Hardness Measurements
This standard is issued under the fixed designation B 934; 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 (ϵ) indicates an editorial change since the last revision or reapproval.
1. Scope information is available in the Related Material section of
Volume 02.05 of the Annual Book of ASTM Standards.
1.1 This test method covers a procedure for determination
3.2 Definitions of Terms Specific to This Standard:
of the effective case depth of powder metallurgy (P/M) parts.
3.2.1 case —that portion of a part, extending inward from
1.2 A microindentation hardness traverse procedure is de-
the surface that has a microindentation hardness, after harden-
scribedtodetermineeffectivecasedepth.Thistestmethodmay
ing, equal to or greater than a specified hardness.
be used to determine the effective case depth for all types of
3.2.2 effective case depth—the perpendicular distance from
hardened cases.
the surface of the hardened case to the furthest point where a
1.3 The procedure for determining the microindentation
microindentation hardness value equivalent to 50 HRC is
hardness of powder metallurgy materials, as described in Test
maintained, unless otherwise specified.
Method B 933B 933 shall be followed.
1.4 This standard does not purport to address all of the
4. Summary of Test Method
safety concerns, if any, associated with its use. It is the
4.1 The powder metallurgy part is sectioned and the surface
responsibility of the user of this standard to establish appro-
prepared for examination. Microindentation hardness measure-
priate safety and health practices and determine the applica-
ments are taken at various depths below the part surface. The
bility of regulatory limitations prior to use.
distance where the microindentation hardness falls below the
2. Referenced Documents equivalent of 50 HRC is defined as the effective case depth,
unless otherwise specified.
2.1 ASTM Standards:
B 243 Terminology of Powder Metallurgy
5. Significance and Use
B 933 Test Method for Microindentation Hardness of Pow-
5.1 The engineering function of many P/M parts may
der Metallurgy (P/M) Materials
require an exterior portion of the part to have a specified case
E18 Test Methods for Rockwell Hardness and Rockwell
depth and microindentation hardness. Measurement of effec-
Superficial Hardness of Metallic Materials
tive case depth is used to determine the depth to which the
E 384 Test Method for Microindentation Hardness of Ma-
microindentation hardness of the exterior portion of a part has
terials
been increased over that of the interior of the part.
2.2 Other Standard:
SAE J 423 Recommended Practice, Methods of Measuring
6. Apparatus
Case Depth
6.1 Knoop or Vickers Hardness Indenters, using 100 gf
(0.9807 N) loads are recommended following Test Method
3. Terminology
E 384E 384. The type of hardness indenter and load used shall
3.1 Definitions of powder metallurgy (P/M) terms can be
be agreed upon between customer and producer.
found in Terminology B 243B 243. Additional descriptive
6.2 Calibrated Optical Instrument, Micrometer Stage,or
other suitable means to measure the distance from the surface
of the part to the center of the impression with a precision of
This test method is under the jurisdiction of ASTM Committee B09 on Metal
0.1 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 April 1, 2004. Published April 2004.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 7.1 Cut a test specimen from the P/M part, perpendicular to
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
the hardened surface at a specified location, being careful to
Standards volume information, refer to the standard’s Document Summary page on
avoid any cutting or grinding procedure that would affect the
the ASTM website.
original microindentation hardness.
Available from Society of Automotive Engineers (SAE), 400 Commonwealth
Dr., Warrendale, PA 15096-0001.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
B934–04
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 test specimen using methods distanceatwhichthemicroindentationhardnessfallsbelowthe
recommended in Appendix X2 of Test Method B 933B 933. equivalent of 50 HRC unless a different value is specified (see
The area to be traversed should be polished so the microin- Note 1). Plot definition will dictate the required number of
dentation hardness impressions are unaffected, that is, the readings, particularly in the critical region of effective case
lighter the indenter load, the finer the finish necessary. Care depth. The procedure described in Appendix X1 of Test
should be taken to ensure that the true area fraction of porosity Method B 933B 933 shall be used for conversion to HRC.
is revealed throughout the entire cross-section of the specimen.
NOTE 1—No compositional change occurs in induction hardened ma-
It is essential in surface preparation to remove all smeared
terials The hardness of martensite is affected by the carbon content of the
metal and to identify pores clearly so that they may be avoided
steel. Some lower-carbon steels will not reach the equivalent of 50 HRC
during testing. when fully hardened. All concerned parties should agree upon the
specified effective case depth hardness if other than 50 HRC.
7.4
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