ASTM F1801-97(2004)
(Test Method)Standard Practice for Corrosion Fatigue Testing of Metallic Implant Materials
Standard Practice for Corrosion Fatigue Testing of Metallic Implant Materials
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 37C 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 SI units are to be regarded as the standard.
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 2004)
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. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E1012 PracticeforVerificationofTestFrameandSpecimen
Alignment Under Tensile and Compressive Axial Force
1.1 This practice covers the procedure for performing cor-
Application
rosion fatigue tests to obtain S-N fatigue curves or statistically
E1150 Definitions of Terms Relating to Fatigue
derived fatigue strength values, or both, for metallic implant
F86 Practice for Surface Preparation and Marking of Me-
materials. This practice describes the testing of axially loaded
tallic Surgical Implants
fatigue specimens subjected to a constant amplitude, periodic
F601 Practice for Fluorescent Penetrant Inspection of Me-
forcing function in saline solution at 37°C and in air at room
tallic Surgical Implants
temperature. The environmental test method for implant mate-
G15 Terminology Relating to Corrosion and Corrosion
rials may be adapted to other modes of fatigue loading such as
Testing
bending or torsion. While this practice is not intended to apply
2.2 ANSI Standard:
to fatigue tests on implantable components or devices, it does
ANSI B46.1 Surface Texture
provide guidelines for fatigue tests with standard specimens in
an environment related to physiological conditions.
3. Terminology
1.2 The values stated in SI units are to be regarded as the
3.1 Definitions:
standard.
3.1.1 Theterminologyusedinconjunctionwiththispractice
1.3 This standard does not purport to address all of the
complies to Terminology E1150 and Terminology G15.
safety concerns, if any, associated with its use. It is the
3.2 Definitions of Terms Specific to This Standard:
responsibility of the user of this standard to establish appro-
3.2.1 S-N curves—S-N curves (also known as Wöhler-
priate safety and health practices and determine the applica-
curves) show the correlation between the applied stress (S) and
bility of regulatory limitations prior to use.
the counted number (N) of cycles to failure.
2. Referenced Documents
4. Significance and Use
2.1 ASTM Standards:
4.1 Implants, particularly orthopedic devices, are usually
E4 Practices for Force Verification of Testing Machines
exposed to dynamic forces. Thus, implant materials must have
E466 Practice for Conducting Force Controlled Constant
high fatigue resistance in the physiological environment.
Amplitude Axial Fatigue Tests of Metallic Materials
4.1.1 This practice provides a procedure for fatigue testing
E467 Practice for Verification of Constant Amplitude Dy-
in a simulated physiological environment. Axial tension-
namic Forces in an Axial Fatigue Testing System
tension fatigue tests in an environmental test chamber are
E468 Practice for Presentation of Constant Amplitude Fa-
recommended as a standard procedure. The axial fatigue
tigue Test Results for Metallic Materials
loading shall comply with Practice E466 and Practice E467.
E739 Practice for Statistical Analysis of Linear or Linear-
4.1.1.1 Bending and rotating bending beam fatigue tests or
ized Stress-Life ( S-N) and Strain-Life (e-N) Fatigue Data
torsion tests may be performed in a similar environmental cell.
4.1.2 This practice is intended to assess the fatigue and
ThispracticeisunderthejurisdictionofASTMCommitteeF04onMedicaland
corrosion fatigue properties of materials that are employed or
Surgical Materials and Devices and is the direct responsibility of Subcommittee
projected to be employed for implants.This practice is suitable
F04.15 on Material Test Methods.
for studying the effects of different material treatments and
Current edition approved Aug. 1, 2004. Published August 2004. Originally
approved in 1997. Last previous edition approved in 1997 as F1801 – 97. DOI: surfaceconditionsonthefatiguebehaviorofimplantmaterials.
10.1520/F1801-97R04.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Withdrawn.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F1801–97 (2004)
The loading mode of the actual implants may be different from ronmental test chamber is attached to the equipment and the
that of this practice. Determining the fatigue behavior of environmental tests are carried out under conditions as de-
implants and implant components may require separate tests scribed in this standard. Except for the mechanical testing
that consider the specific design and loading mode. arrangements the conditions of this standard practice apply
4.1.3 As a substitute for body fluid, 0.9 % saline solution is where possible. Reporting should follow Section 9 and should
recommended as a standard environment. One of the various include all details where the testing deviates from the standard
Ringer’ssolutionsoranothersubstituteforbodyfluidmayalso 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
chloride ions are the most critical constituent in these solutions fitted with an environmental test cell surrounding the specimen
in initiating corrosion fatigue. gauge section as shown in Fig. 1. A heated solution reservoir,
4.1.4 Because implants are manufactured from highly cor- a solution pump, and connecting lines for circulating the test
rosion resistant materials, no visible corrosion may be detect- solution to the specimen surface are required. The solution
able 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 phenomena like erosion-corrosion.The reservoir should have a
(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 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 excluded.
laboratory comparisons the following conditions are consid-
6. Test Solution
ered as the standard test. Axial tension-tension tests with
6.1 To prepare the saline solution, dissolve9gof reagent-
cylindrical specimens in 37°C 0.9 % saline solution and air
grade sodium chloride in distilled water and make up to 1000
under a loading frequency of 1 Hz.
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-
7. Test Specimen
lyzed to ensure that the machine is capable of maintaining the
desired form and magnitude of loading for the duration of the 7.1 Specimen Design:
test (see Practice 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). For the dimensional proportions of flat specimens refer
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.
measured dynamically as described in Practice E467 shall be 7.1.1.3 To calculate the load necessary to obtain the re-
maintained within an accuracy of less than or equal to 2 % of quired stress, the cross-sectional area of the specimen test-
the extreme loads applied during testing. section must be measured accurately. The dimensions should
5.3 Non Axial Fatigue Testing—Corrosion fatigue tests be measured to the nearest 0.03 mm (0.001 in.) for specimens
under loading conditions different from axial tension-tension less than 5.00 mm thick (0.197 in.), and to the nearest 0.05 mm
may be requested. In such cases established experimental (0.002 in.) for specimens more than 5.00 mm thick (0.197 in.).
arrangements for bending, rotating bending beam, or torsional Surfacesintendedtobeparallelandstraightshouldbecarefully
testing may replace the axial tension-tension mode. An envi- aligned.
F1801–97 (2004)
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
7.2 Specimen Dimensions—Consult Practice E466 and 7.3.1 The method of surface preparation and the resulting
PracticeE468forthedimensionsoffatiguespecimensforaxial surface condition of the test specimens are of great importance
tension-tension loading (Fig. 2, Fig. 3, Fig. 4, and Fig. 5). If because they influence the test results strongly. Standard
bending specimens corresponding to the example of Practice preparation shall consist of machining, grinding, or polishing,
F466 are used, observe the suggested dimensions. or all of these.Afinal mechanical polish is suggested to give a
7.3 Specimen Preparation: finish of 16 Min RA or less in accordance with ANSI B46.1.
F1801–97 (2004)
FIG. 4 Specimens With Tangentially Blending Fillets Between the Uniform Test Section and the Ends
FIG. 5 Specimens With Continuous Radius Between Ends
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 must 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 such as should thus be reported.
usedorintendedtobeusedforsurgicalimplants.Afullaccount
8. Procedure
of the surface preparation should be given in the test protocol.
7.3.2 Allspecimensusedinanygivenseriesofexperiments, 8.1 Test Set-Up:
including comparison between air and liquid environment, 8.1.1 Specimen grips must 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- should be made to prevent misalignment, due either to twist
less of the machining, grinding or polishing method used, the (rotation of the grips) or to a displacement in their axes of
final mechanical working direction should be approximately symmetry.
parallel to the long axis of the specimen to avoid notch effects 8.1.2 For axial fatigue testing, alignment should be verified
of surface grooves. according to Practice E4, Practice E467, and Practice E1012.
7.3.3 Fillet undercutting and the introduction of residual 8.2 Test Conditions:
stresses into the specimen must be avoided. Both effects can be 8.2.1 The environment shall be air at room temperature or
caused by poor machining practice. Fillet undercutting can be 0.9 weight % NaCl solution at 37 6 1°C. The pH should be
identified by visual inspection. The introduction of unwanted measured before and after the test is begun and should be
residual stresses can be avoided by careful control of the monitored in 24 h intervals, and at the end of the test.
machining process. 8.2.1.1 The specimens should be exposed to the liquid
7.3.4 Specimens that are subject to surface alterations under environment 2 h prior to the start of the cyclic loading.
ambient conditions shall be protected appropriately, preferably 8.2.2 Mechanical test conditions for tension-tension, con-
in an inert medium or exsiccator, to prevent surface
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