1、Designation: F 1801 97 (Reapproved 2004)Standard Practice forCorrosion Fatigue Testing of Metallic Implant Materials1This standard is issued under the fixed designation F 1801; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the procedure for performing cor-rosion fatigue tests to obtain S-N fatigue curves or stat
3、isticallyderived fatigue strength values, or both, for metallic implantmaterials. This practice describes the testing of axially loadedfatigue specimens subjected to a constant amplitude, periodicforcing function in saline solution at 37C and in air at roomtemperature. The environmental test method
4、for implant mate-rials may be adapted to other modes of fatigue loading such asbending or torsion. While this practice is not intended to applyto fatigue tests on implantable components or devices, it doesprovide guidelines for fatigue tests with standard specimens inan environment related to physio
5、logical conditions.1.2 The values stated in SI units are to be regarded as thestandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices
6、and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 4 Practices for Force Verification of Testing MachinesE 466 Practice for Conducting Force Controlled ConstantAmplitude Axial Fatigue Tests of Metallic MaterialsE 467 Practice for Veri
7、fication of Constant Amplitude Dy-namic Loads on Displacements in an Axial Load FatigueTesting MachineE 468 Practice for Presentation of Constant Amplitude Fa-tigue Test Results for Metallic MaterialsE 739 Practice for Statistical Analysis of Linear or Linear-ized Stress-Life (S-N) or Strain-Life (e
8、-N) Fatigue DataE 1012 Practice for Verification of Specimen AlignmentUnder Tensile LoadingE 1150 Definitions of Terms Relating to Fatigue3F 86 Practice for Surface Preparation and Marking of Me-tallic Surgical ImplantsF 601 Practice for Fluorescent Penetrant Inspection of Me-tallic Surgical Implant
9、sG 15 Terminology Relating to Corrosion and CorrosionTesting2.2 ANSI Standard:ANSI B46.1 Surface Texture43. Terminology3.1 Definitions:3.1.1 The terminology used in conjunction with this practicecomplies to Terminology E 1150 and Terminology G 15.3.2 Definitions of Terms Specific to This Standard:3.
10、2.1 S-N curvesS-N curves (also known as Whler-curves) show the correlation between the applied stress (S) andthe counted number (N) of cycles to failure.4. Significance and Use4.1 Implants, particularly orthopedic devices, are usuallyexposed to dynamic forces. Thus, implant materials must havehigh f
11、atigue resistance in the physiological environment.4.1.1 This practice provides a procedure for fatigue testingin a simulated physiological environment. Axial tension-tension fatigue tests in an environmental test chamber arerecommended as a standard procedure. The axial fatigueloading shall comply
12、with Practice E 466 and Practice E 467.4.1.1.1 Bending and rotating bending beam fatigue tests ortorsion tests may be performed in a similar environmental cell.4.1.2 This practice is intended to assess the fatigue andcorrosion fatigue properties of materials that are employed orprojected to be emplo
13、yed for implants. This practice is suitablefor studying the effects of different material treatments andsurface conditions on the fatigue behavior of implant materials.The loading mode of the actual implants may be different fromthat of this practice. Determining the fatigue behavior ofimplants and
14、implant components may require separate teststhat consider the specific design and loading mode.4.1.3 As a substitute for body fluid, 0.9 % saline solution isrecommended as a standard environment. One of the various1This practice is under the jurisdiction of ASTM Committee F04 on Medical andSurgical
15、 Materials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved Aug. 1, 2004. Published August 2004. Originallyapproved in 1997. Last previous edition approved in 1997 as F 1801 97.2For referenced ASTM standards, visit the ASTM website,
16、 www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 1003
17、6.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Ringers solutions or another substitute for body fluid may alsobe suitable for particular tests. However, these various solu-tions may not give equal fatigue endurance results. Thechl
18、oride ions are the most critical constituent in these solutionsin initiating corrosion fatigue.4.1.4 Because implants are manufactured from highly cor-rosion resistant materials, no visible corrosion may be detect-able by optical or electron-optical (SEM) means. Only adecrease of fatigue strength in
19、 the high cyclic life range may benoticeable. Therefore, S-N curves covering a broad fatigueloading range should be generated in 0.9 % saline solution(Ringers solutions) and air. Comparison of fatigue curvesgenerated in air and saline solution may be the only way toassess the effect of the saline en
20、vironment.4.1.5 Where the fatigue behavior of a material system isalready established, it may suffice to test modifications of thematerial properties or surface condition in only a selected stressrange.4.1.6 The recommended loading frequency of one hertzcorresponds to the frequency of weight-bearing
21、 during walk-ing. For screening tests, higher test frequencies may be used;but it must be realized that higher frequencies may affect theresults.4.1.7 Summary of Standard ConditionsFor inter-laboratory comparisons the following conditions are consid-ered as the standard test. Axial tension-tension t
22、ests withcylindrical specimens in 37C 0.9 % saline solution and airunder a loading frequency of 1 Hz.5. Testing Equipment5.1 The mechanics of the testing machine should be ana-lyzed to ensure that the machine is capable of maintaining thedesired form and magnitude of loading for the duration of thet
23、est (see Practice E 4).5.2 Axial Fatigue Testing:5.2.1 Tension-tension fatigue tests may be performed on oneof the following types of axial fatigue testing machines:5.2.1.1 Mechanical,5.2.1.2 Electromechanical or magnetically driven, and5.2.1.3 Hydraulic or electrohydraulic.5.2.2 The machine shall h
24、ave a load-monitoring system,such as a transducer mounted in series with the specimen. Thetest loads shall be monitored continuously in the early stage ofthe test and periodically thereafter, to ensure that the desiredload is maintained. The magnitude of the varying loads,measured dynamically as des
25、cribed in Practice E 467 shall bemaintained within an accuracy of less than or equal to 2 % ofthe extreme loads applied during testing.5.3 Non Axial Fatigue TestingCorrosion fatigue testsunder loading conditions different from axial tension-tensionmay be requested. In such cases established experime
26、ntalarrangements for bending, rotating bending beam, or torsionaltesting may replace the axial tension-tension mode. An envi-ronmental test chamber is attached to the equipment and theenvironmental tests are carried out under conditions as de-scribed in this standard. Except for the mechanical testi
27、ngarrangements the conditions of this standard practice applywhere possible. Reporting should follow Section 9 and shouldinclude all details where the testing deviates from the standardprocedure.5.4 Environmental Chamber:5.4.1 For corrosion fatigue testing, the machine shall befitted with an environ
28、mental test cell surrounding the specimengauge section as shown in Fig. 1. A heated solution reservoir,a solution pump, and connecting lines for circulating the testsolution to the specimen surface are required. The solutionshould be pumped from the reservoir through the system at arate that will ma
29、intain the temperature at 37 6 1C in the testcell, but with flow rates low enough to avoid flow-dependentphenomena like erosion-corrosion. The reservoir should have aminimum capacity of 1000 mL per square centimeter ofspecimen surface exposed to the electrolyte. The reservoir shallbe vented to the a
30、tmosphere. If the solution volume decreases,the reservoir shall be replenished with distilled water tomaintain the saline concentration, or the solution should beexchanged. During long testing periods exchange of thesolution is recommended. A typical environmental test cell foraxial fatigue testing
31、is shown in Fig. 1.5.4.2 The test equipment should be manufactured of mate-rials or should be protected in a manner that corrosion isavoided. In particular galvanic corrosion in conjunction withthe test specimen and loosening of the specimen grips due tocorrosion must be excluded.6. Test Solution6.1
32、 To prepare the saline solution, dissolve9gofreagent-grade sodium chloride in distilled water and make up to 1000mL. If other typical Ringers solutions are used, note thesolution in the report.7. Test Specimen7.1 Specimen Design:7.1.1 Axial Fatigue Testing:7.1.1.1 The design of the axial load fatigu
33、e test specimensshould comply to Practice E 466 (see Fig. 2, Fig. 3, Fig. 4 andFig. 5). For the dimensional proportions of flat specimens referto the drawing in Practice E 468. The ratio of the test sectionarea to end section area will depend on the specimen geometryand should comply to those standa
34、rds. The test specimensspecified in Practice E 466 and Practice E 468 are designed sothat fatigue failure should occur in the section with reduceddiameter and not at the grip section.7.1.1.2 For bending tests one may refer to the specimenconfiguration suggested in Practice E 466.7.1.1.3 To calculate
35、 the load necessary to obtain the re-quired stress, the cross-sectional area of the specimen test-section must be measured accurately. The dimensions shouldbe measured to the nearest 0.03 mm (0.001 in.) for specimensless than 5.00 mm thick (0.197 in.), and to the nearest 0.05 mm(0.002 in.) for speci
36、mens more than 5.00 mm thick (0.197 in.).Surfaces intended to be parallel and straight should be carefullyaligned.7.2 Specimen DimensionsConsult Practice E 466 andPractice E 468 for the dimensions of fatigue specimens foraxial tension-tension loading (Fig. 2, Fig. 3, Fig. 4, and Fig. 5).F 1801 97 (2
37、004)2If bending specimens corresponding to the example of PracticeF 466 are used, observe the suggested dimensions.7.3 Specimen Preparation:7.3.1 The method of surface preparation and the resultingsurface condition of the test specimens are of great importancebecause they influence the test results
38、strongly. Standardpreparation shall consist of machining, grinding, or polishing,or all of these. A final mechanical polish is suggested to give afinish of 16 Min RA or less in accordance with ANSI B46.1.Alternatively a finish with 600 grit paper in the longitudinaldirection may be used. However, sp
39、ecimens that are to becompared should be prepared the same way. MechanicallyFIG. 1 Example for Environmental Chamber for Axial Corrosion Fatigue TestingFIG. 2 Specimens With Tangentially Blending Fillets Between the Test Section and the EndsFIG. 3 Specimens With a Continuous Radius Between EndsF 180
40、1 97 (2004)3finished specimens must then be degreased in acetone, flushedfirst with ethyl alcohol, then with distilled water, and finallyblown dry with warm air.7.3.1.1 Surface passivation may be carried out where ap-propriate (compare Practice F 86).7.3.1.2 The surface preparation may be also exact
41、ly such asused or intended to be used for surgical implants. A full accountof the surface preparation should be given in the test protocol.7.3.2 All specimens used in any given series of experiments,including comparison between air and liquid environment,should be prepared with the same geometry and
42、 by the samemethod to ensure comparable and reproducible results. Regard-less of the machining, grinding or polishing method used, thefinal mechanical working direction should be approximatelyparallel to the long axis of the specimen to avoid notch effectsof surface grooves.7.3.3 Fillet undercutting
43、 and the introduction of residualstresses into the specimen must be avoided. Both effects can becaused by poor machining practice. Fillet undercutting can beidentified by visual inspection. The introduction of unwantedresidual stresses can be avoided by careful control of themachining process.7.3.4
44、Specimens that are subject to surface alterations underambient conditions shall be protected appropriately, preferablyin an inert medium or exsiccator, to prevent surface changeuntil beginning of the test.7.3.5 Visual inspections at a magnification of approximately203 shall be performed on all speci
45、mens. When such inspec-tions reveal potential defects, nondestructive dye penetrant,ultrasonic methods, or other suitable tests may be employed.Dimensional inspection should be conducted without alteringor damaging the specimens surface. Specimens with surfacedefects should not be used for testing.
46、Inspection should takeplace prior to final surface cleaning.7.3.6 Immediately prior to testing, the specimens may besteam sterilized at a temperature of 120 6 10C and a pressureof 0.10 MPa (14.5 psi) to simulate the actual implant surfaceconditions. Specimens shall be allowed to cool to roomtemperat
47、ure prior to testing. This sterilizing procedure is notmandatory. If it is used, it should be employed consistently intest series that are related and should be reported in the testprotocol.7.3.7 In the liquid environmental testing, the time elapsedbetween surface preparation and testing can influen
48、ce theresults due to the growth of a passive film. The elapsed timeshould thus be reported.8. Procedure8.1 Test Set-Up:8.1.1 Specimen grips must be designed so that alignment isconsistently good from one specimen to the next. Every effortshould be made to prevent misalignment, due either to twist(ro
49、tation of the grips) or to a displacement in their axes ofsymmetry.8.1.2 For axial fatigue testing, alignment should be verifiedaccording to Practice E 4, Practice E 467, and Practice E 1012.8.2 Test Conditions:8.2.1 The environment shall be air at room temperature or0.9 weight % NaCl solution at 37 6 1C. The pH should bemeasured before and after the test is begun and should bemonitored in 24 h intervals, and at the end of the test.8.2.1.1 The specimens should be exposed to the liquidenvironment 2 h prior to the start of the cyclic loading.8.2.2 Mechanical test condit
