ASTM F1801-20

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Designation: F1801 − 97 (Reapproved 2014) F1801 − 20
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
1.1 This practice covers the procedure for performing corrosion fatigue tests to obtain S-N (3.2.1) 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E4 Practices for Force Verification of Testing Machines
E466 Practice for Conducting Force Controlled Constant Amplitude Axial Fatigue Tests of Metallic Materials
E467 Practice for Verification of Constant Amplitude Dynamic Forces in an Axial Fatigue Testing System
E468 Practice for Presentation of Constant Amplitude Fatigue Test Results for Metallic Materials
E739 Practice for Statistical Analysis of Linear or Linearized Stress-Life (S-N) and Strain-Life (ε-N) Fatigue Data
E1012 Practice for Verification of Testing Frame and Specimen Alignment Under Tensile and Compressive Axial Force
Application
E1150 Definitions of Terms Relating to Fatigue (Withdrawn 1996)
F86 Practice for Surface Preparation and Marking of Metallic Surgical Implants
F601 Practice for Fluorescent Penetrant Inspection of Metallic Surgical Implants
This practice is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee F04.15
on Material Test Methods.
Current edition approved Oct. 1, 2014Oct. 1, 2020. Published November 2014October 2020. Originally approved in 1997. Last previous edition approved in 20092014
ε1
as F1801 – 97 (2014).(2009) . DOI: 10.1520/F1801-97R14.10.1520/F1801-20.
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volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
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F1801 − 20
G15 Terminology Relating to Corrosion and Corrosion Testing (Withdrawn 2010)
2.2 ANSI Standard:
ANSI B46.1 Surface Texture
3. Terminology
3.1 Definitions:
3.1.1 The terminology used in conjunction with this practice complies to Terminology with E1150 and Terminology G15.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 S-N curves—S-N curves (also known as Wöhler-curves) show the correlation between the applied stress (S) and the counted
number (N) of cycles to failure.
4. Significance and Use
4.1 Implants, particularly orthopedic devices, are usually exposed to dynamic forces. Thus, implant materials must have high
fatigue resistance in the physiological environment.
4.1.1 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
PracticePractices E466 and Practice E467.
4.1.1.1 Bending and rotating bending beam fatigue tests or torsion tests may be performed in a similar environmental cell.
4.1.2 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.
4.1.3 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.
4.1.4 Because implants are manufactured from highly corrosion-resistant materials, no visible corrosion may be detectable by
optical or electron-optical (SEM) means.when inspected by means of optical microscopy or scanning electron microscopy. Only
a decrease of fatigue strength in the high cyclic life cycle 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 the test solution and in air. Comparison of
fatigue curves generated in air and saline solution may be the only way to assess the effect of the saline environment.
4.1.5 Where the fatigue behavior of a material system is already established, it may suffice to test modifications of the material
properties or surface condition in only a selected stress range.
4.1.6 The recommended loading frequency of one hertz corresponds to the frequency of weight-bearing weight bearing during
walking. For screening tests, higher test frequencies may be used; but it must be realized that higher frequencies may affect the
results.
4.1.7 Summary of Standard Conditions—For inter-laboratory comparisons the following conditions are considered as the standard
test. Axial tension-tension tests with cylindrical specimens in 37°C 0.9 % saline solution at 37°C and air at room temperature under
a loading frequency of 1 Hz.
5. Testing Equipment
5.1 The mechanics of the testing machine should be analyzed to ensure that the machine is capable of maintaining the desired form
and magnitude of loading for the duration of the test (see Practices E4).
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F1801 − 20
5.2 Axial Fatigue Testing:
5.2.1 Tension-tension fatigue tests may be performed on one of the following types of axial fatigue testing machines:
5.2.1.1 Mechanical,
5.2.1.2 Electromechanical or magnetically driven, and
5.2.1.3 Hydraulic or electrohydraulic.
5.2.2 The machine shall have a load-monitoring system, such as a transducer mounted in series with the specimen. The test loads
shall be monitored continuously in the early stage of the test and periodically thereafter, to ensure that the desired load is
maintained. The magnitude of the varying loads, measured dynamically as described in Practice E467, shall be maintained within
an accuracy of less than or equal to 2 % of the extreme loads applied during testing.
5.3 Non Axial Fatigue Testing—Corrosion fatigue tests under loading conditions different from axial tension-tension may be
requested. In such cases established experimental arrangements for bending, rotating bending beam, or torsional testing may
replace the axial tension-tension mode. An environmental test chamber is attached to the equipment and the environmental tests
are carried out under conditions as described in this standard. Except for the mechanical testing arrangements the conditions of
this standard practice apply where possible. Reporting should follow Section 9 and should include all details where the testing
deviates from the standard procedure.
5.4 Environmental Chamber:
5.4.1 For corrosion fatigue testing, the machine shall be fitted with an environmental test cell surrounding the specimen gauge
section as shown in Fig. 1. A heated solution reservoir, a solution pump, and connecting lines for circulating the test solution to
the specimen surface are required. The solution should be pumped from the reservoir through the system at a rate that will maintain
the temperature at 37 6 1°C in the test cell, but with flow rates low enough to avoid flow-dependent phenomena like
erosion-corrosion. The reservoir should have a minimum capacity of 1000 mL per square centimeter of specimen surface exposed
to the electrolyte. The reservoir shall be vented to the atmosphere. If the solution volume decreases, the reservoir shall be
replenished with distilled water to maintain the saline concentration, or the solution should be exchanged. During long testing
periods exchange of the solution is recommended. A typical environmental test cell for axial fatigue testing is shown in Fig. 1.
5.4.2 The test equipment should be manufactured of materials or should be protected in such a manner that corrosion is avoided.
In particular galvanic corrosion in conjunction with the test specimen and loosening of the specimen grips due to corrosion must
be avoided.
6. Test Solution
6.1 To prepare the saline solution, dissolve 9 g of reagent-grade sodium chloride in distilled water and make up to 1000 mL. If
other typical Ringer’s solutions are used, note the solution a substitute for 0.9 % saline solution is used, such as one of the various
Ringer’s solutions, note that in the report.
7. Test Specimen
7.1 Specimen Design:
7.1.1 Axial Fatigue Testing:
7.1.1.1 The design of the axial load fatigue test specimens should comply to Practice E466 (see Fig. 2, Fig. 3, Fig. 4, and Fig.
5). For the dimensional proportions of flat specimens refer to the drawing in Practice E468. The ratio of the test section area to
end section area will depend on the specimen geometry and should comply to those standards. The test specimens specified in
PracticePractices E466 and Practice E468 are designed so that fatigue failure should occur in the section with reduced diameter
and not at the grip section.
7.1.1.2 For bending tests one may refer to the specimen configuration suggested in Practice E466.
F1801 − 20
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 required stress, the cross-sectional area of the specimen test-section must be
measured accurately. The di
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