ASTM B795-93(1997)

Designation: B 795 – 93 (Reapproved 1997)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
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.
1. Scope count made of features with etching characteristics different
from that of the matrix.
1.1 This test method covers a metallographic procedure for
4.3 The amount of contaminant is reported as a percent to
determining the percentage of alloyed or unalloyed iron
the nearest 0.1 %.
contamination present in powder forged low-alloy steel parts
and the percentage of alloyed iron contamination in powder-
5. Significance and Use
forged iron and carbon steel parts.
5.1 Cross product contamination occurs whenever alloy
1.2 Property values stated in SI units are the standard.
steel powders are processed in the same equipment as iron
Conversion factors to inch-pound units may be approximate.
powders.
1.3 This standard does not purport to address all of the
5.2 Unalloyed iron particles, because they may not harden
safety concerns, if any, associated with its use. It is the
upon heat treatment, are a potential source of soft spots in
responsibility of the user of this standard to establish appro-
low-alloy steel parts.
priate safety and health practices and determine the applica-
5.3 Alloyed iron particles, having higher hardenability than
bility of regulatory limitations prior to use.
an iron or carbon steel matrix, are a potential source of hard
2. Referenced Documents spots.
5.4 Hard or soft spots may cause problems in service or
2.1 ASTM Standards:
machining.
B 243 Terminology of Powder Metallurgy
5.5 The results of the tests may be used to qualify parts for
E 3 Methods of Preparation of Metallographic Specimens
shipment in accordance with guidelines agreed between pur-
E 562 Practice for Determining Volume Fraction by Sys-
chaser and manufacturer.
tematic Manual Point Count
6. Apparatus
3. Terminology
6.1 Equipment for the metallographic preparation of test
3.1 Definitions—Definitions of powder metallurgy terms
specimens.
can be found in Terminology B 243. Additional descriptive
6.2 A metallographic microscope permitting observation
information is available in the Related Material Section of Vol
and measurement at a magnification of 100 diameters.
02.05 of the Annual Book of ASTM Standards.
3.2 Description of Term Specific to This Standard:
7. Sampling
3.2.1 cross product contamination—the unintentional mix-
7.1 A metallographic specimen shall be taken from the
ing of powders with distinct differences in chemical composi-
powder-forged part. The polished surface of the specimen
tion.
should be not less than that required to superimpose 2500 grid
4. Summary of Test Method points at a magnification of 1003. Multiple sections are
permitted in order to obtain the necessary area for measure-
4.1 A section representing the core region of the part is
ment on small parts.
taken from the powder forged part and prepared for metallo-
7.2 The polished surface shall be parallel to the direction of
graphic examination.
forging, that is, parallel to the direction of travel of the forging
4.2 The polished and etched sample is examined micro-
punch, or as specified in the contract or purchase order, and
scopically at a magnification of 1003 and a systematic point
shall represent an area away from the surface of the part.
This specification is under the jurisdiction of ASTM Committee B-9 on Metal
8. Procedure
Powders and Metal Powder Products and is the direct responsibility of Subcom-
8.1 Preparation of Specimens:
mittee B09.11 on Near-Full Density Powder Metallurgy Materials.
Current edition approved July 15, 1993. Published December 1993. Originally
8.1.1 Polishing—In polishing the specimens, it is highly
...