ASTM B795-93(2002)e1

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e1
Designation:B795–93 (Reapproved 2002)
Standard Test Method for
Determining the Percentage of Alloyed or Unalloyed Iron
Contamination Present in Powder Forged (P/F) Steel Parts
This standard is issued under the fixed designation B 795; 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—Titles of referenced documents were updated and paragraphs 4.3, 6.2, 7.1, and 8.1.2 were revised editorially in June
2002.
1. Scope 4. Summary of Test Method
1.1 This test method covers a metallographic procedure for 4.1 A section representing the core region of the part is
determining the percentage of alloyed or unalloyed iron taken from the powder forged part and prepared for metallo-
contamination present in powder forged low-alloy steel parts graphic examination.
and the percentage of alloyed iron contamination in powder- 4.2 The polished and etched sample is examined micro-
forged iron and carbon steel parts. scopically at a magnification of 1003 and a systematic point
1.2 Property values stated in SI units are the standard. count made of features with etching characteristics different
Conversion factors to inch-pound units may be approximate. from that of the matrix.
1.3 This standard does not purport to address all of the 4.3 The amount of contaminant is reported as a percentage
safety concerns, if any, associated with its use. It is the to the nearest 0.1 %.
responsibility of the user of this standard to establish appro-
5. Significance and Use
priate safety and health practices and determine the applica-
5.1 Cross product contamination occurs whenever alloy
bility of regulatory limitations prior to use.
steel powders are processed in the same equipment as iron
2. Referenced Documents
powders.
2.1 ASTM Standards: 5.2 Unalloyed iron particles, because they may not harden
B 243 Terminology of Powder Metallurgy upon heat treatment, are a potential source of soft spots in
E 3 Practice for Preparation of Metallographic Specimens low-alloy steel parts.
E 562 Test Method for Determining Volume Fraction by 5.3 Alloyed iron particles, having higher hardenability than
Systematic Manual Point Count an iron or carbon steel matrix, are a potential source of hard
spots.
3. Terminology
5.4 Hard or soft spots may cause problems in service or
3.1 Definitions—Definitions of powder metallurgy terms
machining.
can be found in Terminology B 243. Additional descriptive 5.5 The results of the tests may be used to qualify parts for
information is available in the Related Material Section of Vol
shipment in accordance with guidelines agreed between pur-
02.05 of the Annual Book of ASTM Standards. chaser and manufacturer.
3.2 Description of Term Specific to This Standard:
6. Apparatus
3.2.1 cross product contamination—the unintentional mix-
ing of powders with distinct differences in chemical composi- 6.1 Equipment for the metallographic preparation of test
tion. specimens.
6.2 A metallographic microscope permitting observation
and measurement at a magnification of 1003.
This specification is under the jurisdiction of ASTM Committee B09 on Metal
Powders and Metal Powder Products and is the direct responsibility of Subcom-
7. Sampling
mittee B09.11 on Near-Full Density Powder Metallurgy Materials.
Current edition approved July 15, 1993. Published December 1993. Originally
7.1 Take a metallographic specimen from the powder-
published as B 795 – 88. Last previous edition B 795 – 88.
forgedpart.Thepolishedsurfaceofthespecimenshouldbenot
Annual Book of ASTM Standards, Vol 02.05.
less than that required to superimpose 2500 grid points at a
Annual Book of ASTM Standards, Vol 03.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B795
magnification of 1003. Multiple sections are permitted in from unalloyed iron contamination because the particles etch
order to obtain the necessary area for measurement on small differently (see Fig. 1 and Fig. 2).
parts. 8.2 Examination—Superimpose a grid of between 100 and
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