1、August 2008DEUTSCHE NORM English price group 11No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 77.060!$Q3“1461697www.d
2、in.deDDIN EN ISO 11782-1Corrosion of metals and alloys Corrosion fatigue testing Part 1: Cycles to failure testing (ISO 11782-1:1998)English version of DIN EN ISO 11782-1:2008-08Korrosion von Metallen und Legierungen Prfung der Schwingungskorrosion Teil 1: Prfung unter Anwendung von Bruch-Schwingspi
3、elen (ISO 11782-1:1998)Englische Fassung DIN EN ISO 11782-1:2008-08www.beuth.deDocument comprises 17 pagesDIN EN ISO 11782-1:2008-08 2 National foreword This standard has been prepared by Technical Committee ISO/TC 156 “Corrosion of metals and alloys” (Secretariat: GOST R (Russian Federation). Based
4、 on the results of the unique acceptance procedure, ISO 11782-1:1998 has been adopted by Technical Committee CEN/TC 262 “Metallic and other inorganic coatings” (Secretariat: BSI, United Kingdom) as a European Standard. The responsible German body involved in its preparation was the Normenausschuss M
5、aterialprfung (Materials Testing Standards Committee), Technical Committee NA 062-01-71 AA Korrosion und Korrosions-schutz. ISO 7539-1:1987 DIN EN ISO 7539-1:1995-08 National Annex NA (informative) Bibliography DIN EN ISO 7539-1:1995-08, Corrosion of metals and alloys Stress corrosion testing Part 1
6、: General guidance on testing procedures (ISO 7539-1:1987) The DIN Standard corresponding to the International Standard referred to in clause 2 of the EN is as follows: EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 11782-1 April 2008 ICS 77.060 English Version Corrosion of metals and allo
7、ys - Corrosion fatigue testing - Part 1: Cycles to failure testing (ISO 11782-1:1998) Corrosion des mtaux et alliages - Essais de fatigue-corrosion - Partie 1: Essais cycliques la rupture (ISO 11782-1:1998) Korrosion von Metallen und Legierungen - Prfung der Schwingungskorrosion - Teil 1: Prfung unt
8、er Anwendung von Bruch-Schwingspielen (ISO 11782-1:1998) This European Standard was approved by CEN on 21 March 2008. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without a
9、ny alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made
10、 by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, Franc
11、e,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR N
12、ORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 11782-1:2008: E2 DIN EN ISO 11782-1:2008-08 EN ISO 11782-1:2008 (E) Contents Page Foreword3 Introduction.4 1 Sco
13、pe .5 2 Normative reference 5 3 Definitions 5 4 Test7 4.1 Principle .7 4.2 Specimens .7 4.3 Environmental considerations 11 4.4 Stressing considerations. 12 5 Apparatus . 12 6 Procedure 13 7 Test report . 13 Annex A (informative) Bibliography . 15 3 EN ISO 11782-1:2008 (E) DIN EN ISO 11782-1:2008-08
14、 Foreword The text of ISO 11782-1:1998 has been prepared by Technical Committee ISO/TC 156 “Corrosion of metals and alloys” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 11782-1:2008 by Technical Committee CEN/TC 262 “Metallic and other inorganic coati
15、ngs” the secretariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October 2008, and conflicting national standards shall be withdrawn at the latest by October 2008. Att
16、ention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations o
17、f the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slo
18、vakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 11782-1:1998 has been approved by CEN as a EN ISO 11782-1:2008 without any modification. IntroductionThe study of cycles to failure testing uses plain or notched specimens toprovide data on the int
19、rinsic corrosion fatigue crack like behaviour of ametal or alloy and can be used to develop criteria for engineering design toprevent fatigue failures.The study of cycles to failure can be applied to a wide variety of productforms including plate, rod, wire, sheet and tubes as well as to parts joine
20、dby welding.The results of corrosion fatigue testing are suitable for direct applicationonly when the service conditions exactly parallel the test conditions es-pecially with regard to material, environmental and stressing consider-ations. The combination of material/load/environmental may not be di
21、rectlycomparable to the application. For these cases engineering judgementmust be applied.4 DIN EN ISO 11782-1:2008-08 EN ISO 11782-1:2008 (E) 1 Scope1.1 This International Standard provides guidance and instruction on corrosion fatigue testing of metals and alloysin aqueous or gaseous environments
22、and is concerned with cycles to failure testing. Crack propagation testing isconsidered in ISO 11782-2.1.2 Corrosive or otherwise chemically active environments can promote the initiation of fatigue cracks in metalsand alloys and increase the rate of fatigue crack propagation. Corrosion fatigue proc
23、esses are not limited to specificmetal/environment systems and reliable estimates of fatigue life for all combinations of loading and environmentcannot be made without data from laboratory tests.1.3 This International Standard is not intended for application to corrosion fatigue testing of component
24、s or parts;nevertheless many of the general principles will apply.2 Normative referenceThe following standard contains provisions which, through reference in this text, constitute provisions of this part ofISO 11782. At the time of publication, the edition indicated was valid. All standards are subj
25、ect to revision, andparties to agreements based on this part of ISO 11782 are encouraged to investigate the possibility of applying themost recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currently validInternational Standards.ISO 7539-1:1987, Corrosion o
26、f metals and alloys Stress corrosion testing Part 1: General guidance on testingprocedures.3 DefinitionsFor the purposes of this part of ISO 11782, the following definitions apply.3.1 corrosion fatigue: Process involving conjoint corrosion and alternating straining of the metal, often leading tocrac
27、king.NOTE Corrosion fatigue may occur when a metal is subjected to cyclic straining in a corrosive environment.3.2 stress amplitude, Sa, in fatigue loading: One half of the range of a cycle (also known as the alternatingstress):SSSamax min2=-5 EN ISO 11782-1:2008 (E) DIN EN ISO 11782-1:2008-08 3.3 m
28、ean stress, Sm, in fatigue loading: Algebraic average of the maximum and minimum stresses in constantamplitude loading or of individual cycles in spectrum loading:SSSmmax min2=+3.4 maximum stress, Smax, in fatigue loading: That stress having the highest algebraic value:SSSmax m a=+3.5 minimum stress
29、, Smin, in fatigue loading: That stress having the lowest algebraic value:SSSmin ma=3.6 stress ratio, R, in fatigue loading: Algebraic ratio of the minimum and maximum stress of a cycle:RSS=minmaxNOTE The stress ratio, R, is equal to the load ratio Pmin /Pmax, where Pminand Pmaxare the minimum and m
30、aximum loads inthe cycle, respectively.3.7 S-N diagram: Plot of stress against the number of cycles to failure.The stress can be the maximum stress, Smax, minimum stress, Smin, stress range, DS or Sr, or alternating stress, Sa.The diagram indicates the S-N relationship for a specified value of Sm, R
31、 and a specified probability of survival. ForN, a log scale is almost always used. For S, a linear scale or a log scale is used.3.8 fatigue notch factor, Kf: Ratio of the fatigue strength of a specimen with no stress concentrator to that of aspecimen with a stress concentrator for the same percent s
32、urvival at N cycles for the same loading andenvironmental conditions.NOTE In specifying Kf, it is necessary to specify the geometry and the values of stress amplitude, mean stress and N forwhich it is computed.3.9 stress concentration factor, Kt: Ratio of the greatest stress in the region of a notch
33、 or other stressconcentrator as determined by the theory of elasticity to the corresponding nominal stress.Ktbecomes invalid when the stress at the notch root exceeds the yield strength.3.10 cycle (in fatigue): Smallest segment of the load- or stress-time function which is repeated periodically. The
34、terms fatigue cycle, load cycle and stress cycle are also commonly used.3.11 waveform: Shape of the peak-to-peak variation of load as a function of time.3.12 cyclic frequency, f: Number of cycles per unit time, usually expressed in terms of cycles per second (Hz).3.13 fatigue strength at N load cycl
35、es, SN: Value of stress for failure at exactly N load cycles as determinedfrom an S-N diagram. The value of SNthus determined is subject to the same conditions as those that apply to theS-N diagram.NOTES1 The value of SNis also known as the median fatigue strength for N cycles.2 In a corrosive envir
36、onment the fatigue strength is likely to be reduced compared with that in air.6 DIN EN ISO 11782-1:2008-08 EN ISO 11782-1:2008 (E) 3.14 fatigue strength limit, Sf: Limiting value of the median fatigue strength as the fatigue life, N, becomes verylarge. Most materials and environments preclude the at
37、tainment of well defined fatigue limits.4 Test4.1 PrincipleIn the presence of an aggressive environment the fatigue strength of a metal or alloy is reduced to an extent whichdepends on the nature of the environment and the test conditions. For example, the well-defined fatigue strengthlimit observed
38、 for steels in air may no longer be evident as illustrated in figure 1. Interpretation of results is thenbased on the assumption of an acceptable life of the component.The test involves subjecting a series of specimens to the number of stress cycles required for a fatigue crack toinitiate and grow l
39、arge enough to cause failure during exposure to a corrosive or otherwise chemically activeenvironment at progressively smaller alternating stresses in order to define either the fatigue strength at N cycles,SN, from an S-N diagram or the fatigue strength limit as the fatigue life becomes very large.
40、The test is used to determine the effect of environment, material, geometry, surface condition, stress, etc, on thecorrosion fatigue resistance of metals or alloys subjected to applied stress for relatively large numbers of cycles.The test may also be used as a guide to the selection of materials fo
41、r service under conditions of repeated appliedstress under known environmental conditions.4.2 Specimens4.2.1 GeneralThe design and type of specimen used depends on the fatigue testing machine used, the objective of the fatiguestudy and the form of the material from which the specimen is to be made.
42、Fatigue test specimens are designedaccording to the mode of loading which can include axial stressing, plane bending, rotating beam, alternate torsionor combined stress.Specimens may have circular, square, rectangular, annular or, in special cases, other cross-sections.The gripped ends may be of any
43、 shape to suit the holders of the test machine. Problems may arise unless thegripped portion of the specimen is isolated from the corrosive test environment.The test section of the specimen shall be reduced in cross-section to prevent failure in the grip ends and should beof such a size as to use th
44、e middle to upper ranges of the load rating of the fatigue machine to optimize thesensitivity and response of the system.The transition from the gauge section to the gripped ends of the specimen shall be designed to minimize any stressconcentration. It is recommended that the radius of the blending
45、fillet shall be at least eight times the specimen testsection diameter or width. The cross-sectional area of the gripped ends shall, where possible, be at least four timesthat of the test section area.The test section length shall be greater than three times the test section diameter or width.For te
46、sts run in compression, the length of the test section shall be less than four times the test section diameter orwidth in order to minimize buckling.For the purposes of calculating the load to be applied to obtain the required stress, the dimensions from which thearea is calculated shall be measured
47、 to within 0,02 mm.Specimens shall be identified by an indelible marking method, such as stamping, on surface areas, preferably onthe plain ends, without having an influence on the test results.Specimens shall be stored after appropriate cleaning under desiccated conditions prior to testing in order
48、 to avoidcorrosion which may influence the test results.7 EN ISO 11782-1:2008 (E) DIN EN ISO 11782-1:2008-08 4.2.2 Cylindrical specimensTwo types of specimens with circular cross-section are frequently used for corrosion fatigue tests:a) specimens with tangentially blending fillets between the test
49、section and the grip ends (see figure 2); theseare suitable where axial loading is employed;b) specimens with a continuous radius between the grip ends with the minimum diameter at the centre (seefigure 3); these are suitable for rotating bend tests.A minimum cross-section diameter of 5 mm is preferred.4.2.3 Flat sheet or plate specimensFlat specimens for fatigue tests are reduced in width in the test section and may have thickness reductions.If the specimen thickness is less than 2,5 mm, and the tests are performed in
