ASTM F1801-97(2009)e1
(Test Method)Standard Practice for Corrosion Fatigue Testing of Metallic Implant Materials
Standard Practice for Corrosion Fatigue Testing of Metallic Implant Materials
SIGNIFICANCE AND USE
Implants, particularly orthopedic devices, are usually exposed to dynamic forces. Thus, implant materials must have high fatigue resistance in the physiological environment.
This practice provides a procedure for fatigue testing in a simulated physiological environment. Axial tension-tension fatigue tests in an environmental test chamber are recommended as a standard procedure. The axial fatigue loading shall comply with Practice E466 and Practice E467.
Bending and rotating bending beam fatigue tests or torsion tests may be performed in a similar environmental cell.
This practice is intended to assess the fatigue and corrosion fatigue properties of materials that are employed or projected to be employed for implants. This practice is suitable for studying the effects of different material treatments and surface conditions on the fatigue behavior of implant materials. The loading mode of the actual implants may be different from that of this practice. Determining the fatigue behavior of implants and implant components may require separate tests that consider the specific design and loading mode.
As a substitute for body fluid, 0.9 % saline solution is recommended as a standard environment. One of the various Ringer's solutions or another substitute for body fluid may also be suitable for particular tests. However, these various solutions may not give equal fatigue endurance results. The chloride ions are the most critical constituent in these solutions for initiating corrosion fatigue.
Because implants are manufactured from highly corrosion-resistant materials, no visible corrosion may be detectable by optical or electron-optical (SEM) means. Only a decrease of fatigue strength in the high cyclic life range may be noticeable. Therefore, S-N curves covering a broad fatigue loading range should be generated in 0.9 % saline solution (Ringer's solutions) and air. Comparison of fatigue curves generated in air and saline solution may be the only way to assess the...
SCOPE
1.1 This practice covers the procedure for performing corrosion fatigue tests to obtain S-N fatigue curves or statistically derived fatigue strength values, or both, for metallic implant materials. This practice describes the testing of axially loaded fatigue specimens subjected to a constant amplitude, periodic forcing function in saline solution at 37°C and in air at room temperature. The environmental test method for implant materials may be adapted to other modes of fatigue loading such as bending or torsion. While this practice is not intended to apply to fatigue tests on implantable components or devices, it does provide guidelines for fatigue tests with standard specimens in an environment related to physiological conditions.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
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: F1801 − 97(Reapproved 2009)
Standard Practice for
Corrosion Fatigue Testing of Metallic Implant Materials
This standard is issued under the fixed designation F1801; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
´ NOTE—Units information was editorially corrected in January 2010.
1. Scope E468Practice for Presentation of Constant Amplitude Fa-
tigue Test Results for Metallic Materials
1.1 This practice covers the procedure for performing cor-
E739PracticeforStatisticalAnalysisofLinearorLinearized
rosion fatigue tests to obtain S-N fatigue curves or statistically
Stress-Life (S-N) and Strain-Life (´-N) Fatigue Data
derived fatigue strength values, or both, for metallic implant
E1012Practice for Verification of Testing Frame and Speci-
materials. This practice describes the testing of axially loaded
men Alignment Under Tensile and Compressive Axial
fatigue specimens subjected to a constant amplitude, periodic
Force Application
forcing function in saline solution at 37°C and in air at room
E1150Definitions of Terms Relating to Fatigue (Withdrawn
temperature. The environmental test method for implant mate-
1996)
rials may be adapted to other modes of fatigue loading such as
F86Practice for Surface Preparation and Marking of Metal-
bending or torsion.While this practice is not intended to apply
lic Surgical Implants
to fatigue tests on implantable components or devices, it does
F601Practice for Fluorescent Penetrant Inspection of Me-
provide guidelines for fatigue tests with standard specimens in
tallic Surgical Implants
an environment related to physiological conditions.
G15Terminology Relating to Corrosion and CorrosionTest-
1.2 The values stated in either SI units or inch-pound units
ing (Withdrawn 2010)
are to be regarded separately as standard. The values stated in
2.2 ANSI Standard:
each system may not be exact equivalents; therefore, each
ANSI B46.1Surface Texture
system shall be used independently of the other. Combining
values from the two systems may result in non-conformance
3. Terminology
with the standard.
3.1 Definitions:
1.3 This standard does not purport to address all of the
3.1.1 Theterminologyusedinconjunctionwiththispractice
safety concerns, if any, associated with its use. It is the
complies to Terminology E1150 and Terminology G15.
responsibility of the user of this standard to establish appro-
3.2 Definitions of Terms Specific to This Standard:
priate safety and health practices and determine the applica-
3.2.1 S-N curves—S-N curves (also known as Wöhler-
bility of regulatory limitations prior to use.
curves)showthecorrelationbetweentheappliedstress(S)and
the counted number (N) of cycles to failure.
2. Referenced Documents
2.1 ASTM Standards:
4. Significance and Use
E4Practices for Force Verification of Testing Machines
E466Practice for Conducting Force Controlled Constant 4.1 Implants, particularly orthopedic devices, are usually
exposed to dynamic forces. Thus, implant materials must have
Amplitude Axial Fatigue Tests of Metallic Materials
high fatigue resistance in the physiological environment.
E467Practice for Verification of Constant Amplitude Dy-
4.1.1 This practice provides a procedure for fatigue testing
namic Forces in an Axial Fatigue Testing System
in a simulated physiological environment. Axial tension-
tension fatigue tests in an environmental test chamber are
ThispracticeisunderthejurisdictionofASTMCommitteeF04onMedicaland
recommended as a standard procedure. The axial fatigue
Surgical Materials and Devices and is the direct responsibility of Subcommittee
loading shall comply with Practice E466 and Practice E467.
F04.15 on Material Test Methods.
Current edition approved Dec. 1, 2009. Published January 2010. Originally
approved in 1997. Last previous edition approved in 2004 as F1801–97(2004).
DOI: 10.1520/F1801-97R09E01.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or The last approved version of this historical standard is referenced on
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM www.astm.org.
Standards volume information, refer to the standard’s Document Summary page on Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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F1801 − 97 (2009)
4.1.1.1 Bending and rotating bending beam fatigue tests or measured dynamically as described in Practice E467, shall be
torsion tests may be performed in a similar environmental cell. maintained within an accuracy of less than or equal to 2% of
4.1.2 This practice is intended to assess the fatigue and the extreme loads applied during testing.
corrosion fatigue properties of materials that are employed or
5.3 Non Axial Fatigue Testing—Corrosion fatigue tests un-
projectedtobeemployedforimplants.Thispracticeissuitable
derloadingconditionsdifferentfromaxialtension-tensionmay
for studying the effects of different material treatments and
be requested. In such cases established experimental arrange-
surfaceconditionsonthefatiguebehaviorofimplantmaterials.
ments for bending, rotating bending beam, or torsional testing
Theloadingmodeoftheactualimplantsmaybedifferentfrom
may replace the axial tension-tension mode.An environmental
that of this practice. Determining the fatigue behavior of
test chamber is attached to the equipment and the environmen-
implants and implant components may require separate tests
tal tests are carried out under conditions as described in this
that consider the specific design and loading mode.
standard. Except for the mechanical testing arrangements the
4.1.3 As a substitute for body fluid, 0.9% saline solution is
conditions of this standard practice apply where possible.
recommended as a standard environment. One of the various
Reporting should follow Section 9 and should include all
Ringer’ssolutionsoranothersubstituteforbodyfluidmayalso
details where the testing deviates from the standard procedure.
be suitable for particular tests. However, these various solu-
5.4 Environmental Chamber:
tions may not give equal fatigue endurance results. The
5.4.1 For corrosion fatigue testing, the machine shall be
chlorideionsarethemostcriticalconstituentinthesesolutions
fittedwithanenvironmentaltestcellsurroundingthespecimen
for initiating corrosion fatigue.
gauge section as shown in Fig. 1. A heated solution reservoir,
4.1.4 Because implants are manufactured from highly
a solution pump, and connecting lines for circulating the test
corrosion-resistant materials, no visible corrosion may be
solution to the specimen surface are required. The solution
detectable by optical or electron-optical (SEM) means. Only a
should be pumped from the reservoir through the system at a
decreaseoffatiguestrengthinthehighcyclicliferangemaybe
rate that will maintain the temperature at 37 6 1°C in the test
noticeable. Therefore, S-N curves covering a broad fatigue
cell, but with flow rates low enough to avoid flow-dependent
loading range should be generated in 0.9% saline solution
phenomenalikeerosion-corrosion.Thereservoirshouldhavea
(Ringer’s solutions) and air. Comparison of fatigue curves
minimum capacity of 1000 mL per square centimeter of
generated in air and saline solution may be the only way to
specimensurfaceexposedtotheelectrolyte.Thereservoirshall
assess the effect of the saline environment.
be vented to the atmosphere. If the solution volume decreases,
4.1.5 Where the fatigue behavior of a material system is
the reservoir shall be replenished with distilled water to
already established, it may suffice to test modifications of the
maintain the saline concentration, or the solution should be
materialpropertiesorsurfaceconditioninonlyaselectedstress
exchanged. During long testing periods exchange of the
range.
solution is recommended.Atypical environmental test cell for
4.1.6 The recommended loading frequency of one hertz
axial fatigue testing is shown in Fig. 1.
corresponds to the frequency of weight-bearing during walk-
5.4.2 The test equipment should be manufactured of mate-
ing. For screening tests, higher test frequencies may be used;
rials or should be protected in such a manner that corrosion is
but it must be realized that higher frequencies may affect the
avoided. In particular galvanic corrosion in conjunction with
results.
the test specimen and loosening of the specimen grips due to
4.1.7 Summary of Standard Conditions—For inter-
corrosion must be avoided.
laboratory comparisons the following conditions are consid-
ered as the standard test. Axial tension-tension tests with
6. Test Solution
cylindrical specimens in 37°C 0.9% saline solution and air
6.1 To prepare the saline solution, dissolve9gof reagent-
under a loading frequency of 1 Hz.
grade sodium chloride in distilled water and make up to 1000
mL. If other typical Ringer’s solutions are used, note the
5. Testing Equipment
solution in the report.
5.1 The mechanics of the testing machine should be ana-
lyzed to ensure that the machine is capable of maintaining the
7. Test Specimen
desired form and magnitude of loading for the duration of the
7.1 Specimen Design:
test (see Practices E4).
7.1.1 Axial Fatigue Testing:
5.2 Axial Fatigue Testing: 7.1.1.1 The design of the axial load fatigue test specimens
5.2.1 Tension-tensionfatiguetestsmaybeperformedonone
should comply to Practice E466 (see Fig. 2, Fig. 3, Fig. 4 and
of the following types of axial fatigue testing machines: Fig.5).Forthedimensionalproportionsofflatspecimensrefer
5.2.1.1 Mechanical,
to the drawing in Practice E468. The ratio of the test section
5.2.1.2 Electromechanical or magnetically driven, and area to end section area will depend on the specimen geometry
5.2.1.3 Hydraulic or electrohydraulic. and should comply to those standards. The test specimens
5.2.2 The machine shall have a load-monitoring system, specified in Practice E466 and Practice E468 are designed so
such as a transducer mounted in series with the specimen. The that fatigue failure should occur in the section with reduced
test loads shall be monitored continuously in the early stage of diameter and not at the grip section.
the test and periodically thereafter, to ensure that the desired 7.1.1.2 For bending tests one may refer to the specimen
load is maintained. The magnitude of the varying loads, configuration suggested in Practice E466.
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F1801 − 97 (2009)
FIG. 1 Example for Environmental Chamber for Axial Corrosion Fatigue Testing
FIG. 2 Specimens With Tangentially Blending Fillets Between the Test Section and the Ends
FIG. 3 Specimens With a Continuous Radius Between Ends
7.1.1.3 To calculate the load necessary to obtain the re- lessthan5.00mmthick[0.197in.],andtothenearest0.05mm
quired stress, the cross-sectional area of the specimen test- [0.002 in.] for specimens more than 5.00 mm thick [0.197 in.].
section must be measured accurately. The dimensions should Surfacesintendedtobeparallelandstraightshouldbecarefully
be measured to the nearest 0.03 mm [0.001 in.] for specimens aligned.
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F1801 − 97 (2009)
FIG. 4 Specimens With Tangentially Blending Fillets Between the Uniform Test Section and the Ends
FIG. 5 Specimens With Continuous Radius Between Ends
7.2 Specimen Dimensions—Consult Practice E466 and in an inert medium or exsiccator, to prevent surface change
PracticeE468forthedimensionsoffatiguespecimensforaxial until the beginning of the test.
tension-tension loading (Fig. 2, Fig. 3, Fig. 4, and Fig. 5). If 7.3.5 Visualinspectionsatamagnificationofapproximately
bending specimens corresponding to the example of Practice 20× shall be performed on all specimens. When such inspec-
F466 are used, observe the suggested dimensions. tions reveal potential defects, nondestructive dye penetrant,
ultrasonic methods, or other suitable tests may be employed.
7.3 Specimen Preparation:
Dimensional inspection should be conducted without altering
7.3.1 The method of surface preparation and the resulting
or damaging the specimen’s surface. Specimens with surface
surface condition of the test specimens are of great importance
defects should not be used for testing. Inspection should take
because they influence the test results strongly. Standard
place prior to final surface cleaning.
preparation shall consist of machining, grinding, or polishing,
7.3.6 Immediately prior to testing, the specimens may be
or all of these.Afinal mechanical polish is suggested to give a
steamsterilizedatatemperatureof120 610°Candapressure
finish of 16 Min RA or less in accordance with ANSI B46.1.
of 0.10 MPa [14.5 psi] to simulate the actual implant surface
Alternatively, a finish with 600 grit paper in the longitudinal
conditions. Specimens shall be allowed to cool to room
direction may be used. However, specimens that are to be
temperature prior to testing. This sterilizing procedure is not
compared should be prepared the same way. Mechanically
mandatory. If it is used, it should be employed consistently in
finished specimens shall then be degreased in acetone, flushed
test series that are related and should be reported in the test
first with ethyl alcohol, then with distilled water, and finally
protocol.
blown dry with warm air.
7.3.7 In the liquid environmental testing, the time elapsed
7.3.1.1 Surface passivation may be carried out where ap-
between surface preparation and testing can influence the
propriate (compare Practice F86).
results due to the growth of a passive film. The elapsed time
7.3.1.2 The surface preparation may be also exactly as used
should thus be reported.
or intended to be used for surgical implants.Afull account of
the surface preparation should be given in the test protocol.
8. Procedure
7.3.2 Allspecimensusedinanygivenseriesofexperiments,
8.1 Test Set-Up:
includingcomparisonbetweentheairandliquidenvironments,
8.1.1 Specimen grips shall be designed so that alignment is
should be prepared with the same geometry and by the same
consistently good from one specimen to the next. Every effort
methodtoensurecomparableandreproducibleresults.Regard-
shouldbemadetopreventmisalignment,dueeithertotwisting
less of the machining, grinding or polishing method used, the
(rotation of the grips) or to displacement in their axes of
final mechanical working direction should be approximately
symmetry.
parallel to the long axis o
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