ASTM B312-96
(Test Method)Standard Test Method for Green Strength for Compacted Metal Powder Specimens
Standard Test Method for Green Strength for Compacted Metal Powder Specimens
SCOPE
1.1 This test method covers determination of the green strength of unsintered compacted metal powder specimens by subjecting them to a uniformly increasing transverse loading under controlled conditions. The term green strength, as used herein, defines the stress, calculated from the flexure formula, required to break a specimen as a simple beam supported near the ends and applying the force midway between the fixed line center of the supports.
1.2 The values stated in inch-pound units are to be regarded as the standard. The SI equivalents are in parentheses and may be approximate.
1.3 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.
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Designation: B 312 – 96
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
Green Strength for Compacted Metal Powder Specimens
This standard is issued under the fixed designation B 312; 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 4.3 Green strength or maximum fiber stress of the material
under test is determined by calculation using the equation for
1.1 This test method covers determination of the green
a simply supported beam with a concentrated load.
strength of unsintered compacted metal powder specimens by
subjecting them to a uniformly increasing transverse loading
5. Significance and Use
under controlled conditions. The term green strength, as used
5.1 The test for green strength of a compacted metal powder
herein, defines the stress, calculated from the flexure formula,
is useful as a:
required to break a specimen as a simple beam supported near
5.1.1 Method to relate the resistance of a pressed compact to
the ends and applying the force midway between the fixed line
breakage or damage due to handling.
center of the supports.
5.1.2 Means of quality comparison of metal powder, lot to
1.2 The values stated in inch-pound units are to be regarded
lot.
as the standard. The SI equivalents are in parentheses and may
5.1.3 Method of determining the effect of additions to a base
be approximate.
powder.
1.3 This standard does not purport to address all of the
5.2 Significant variations in green strength will occur if the
safety concerns, if any, associated with its use. It is the
density tolerance of the pressed bar is exceeded.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
6. Apparatus
bility of regulatory limitations prior to use.
6.1 Punches and Die (see Fig. 1), for producing a test
2. Referenced Documents specimen having a nominal die dimension of 0.500 in. (12.70
mm) wide by 1.250 in. (31.75 mm) long.
2.1 ASTM Standards:
2 6.2 Compression Testing Machine or Powder Press, capable
B 243 Terminology of Powder Metallurgy
of applying the required pressure to produce, and break if
3. Terminology desired, the standard test specimen.
6.3 Balance, suitable for weighing to an accuracy of 0.01 g.
3.1 Definitions of powder metallurgy (P/M) terms can be
6.4 Micrometers, capable of measuring from 0.0 to 1.25 in.
found in Terminology B 243. Additional descriptive informa-
(0.0 to 31.8 mm) with an accuracy of 0.001 in. (0.03 mm).
tion is available in the Related Material section of Vol 02.05 of
6.5 Either of the following testing apparatus:
the Annual Book of ASTM Standards.
6.5.1 Constant Loading Beam Device as shown in Fig. 2,
4. Summary of Test Method
capable of measuring the breaking force on the test specimen
to the nearest 0.1 lbf (0.5 N).
4.1 The powder to be tested is pressed in a die to the
6.5.2 Transverse Rupture Test Fixture as shown in Fig. 3,
configuration of a bar having a standard rectangular shape in
for use with a compression testing machine to locate the test
the pressing direction and to one of two thicknesses. Either the
bar so the breaking force can be measured to the nearest 0.1 lbf
powder to be pressed contains lubricant or the surfaces of the
(0.5 N).
die are lubricated at each pressing.
4.2 The pressed test specimen’s width, thickness, and den-
7. Test Specimen
sity are determined. The load necessary to fracture the bar is
7.1 The test specimen has nominal dimensions of 0.500 in.
determined by applying a uniformly increasing force to the
(12.70 mm) wide by 1.250 in. (31.75 mm) long by either 0.250
specimen while supporting it in the prescribed three-point bend
in. (6.35 mm) or 0.500 in. (12.70 mm) thick. The green density
test fixture.
shall be within 60.05 g/cm of the target.
8. Procedure
This test method is under the jurisdiction of ASTM Committee B-9 on Metal
Powders and Metal Powder Products and is the direct responsibility of Subcom-
8.1 For lubricated powders follow the instructions starting
mittee B09.02 on Base Metal Powders.
in Section 8.2. The method of lubrication of the powders shall
Current edition approved Sept. 10, 1996. Published December 1996. Originally
e1
published as B 312 –56 T. Last previous edition B 312 – 82 (1988) .
Annual Book of ASTM Standards, Vol 02.05.
B 312
0.005 in. (12.7 6 0.13 mm).
8.5 After ejection from the die, weigh the specimen to the
nearest 0.01 g, measure the specimen dimensions to the nearest
0.001 in. (0.03 mm), and identify the top of the specimen.
Calculate the density of the green specimen. If the specimen
density is within the tolerance, place the specimen in the
transverse rupture test fixture or the constant loading beam
device perpendicular to the supporting rods with the top
uppermost. In the case of the transverse rupture test fixture,
place the loaded fixture between the platens of the compression
testing machine set for an initial crosshead velocity of approxi-
mately 0.1 in./min and apply a uniformly increasing force at a
rate of approximately 20 lbf (89 N)/min until rupture occurs.
Record the breaking force in lbf (or N) to the nearest 0.1 lbf
(0.5 N). When using the constant loading beam device (Fig. 2),
shot is allowed to flow into a suitable container at a rate that
will produce approximately 20 lbf (89 N)/min on the specimen.
The mass of the shot is determined to the nearest gram (0.0022
lb) and t
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