1、BRITISH STANDARD BS EN ISO 11782-1:2008 Corrosion of metals and alloys Corrosion fatigue testing Part 1: Cycles to failure testing ICS 77.060 BS EN ISO 11782-1:2008 This British Standard was published under the authority of the Standards Board and comes into effect on 15 October 1998 BSI 2008 ISBN 9
2、78 0 580 60535 2 National foreword This British Standard is the UK implementation of EN ISO 11782-1:2008. It is identical with ISO 11782-1:1998. It supersedes BS ISO 11782-1:1998 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee ISE/NFE/8, Corrosion of
3、metals and alloys. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot
4、confer immunity from legal obligations. Amendments/corrigenda issued since publication Date Comments 31 July 2008 This corrigendum renumbers BS ISO 11782-1:1998 as BS EN ISO 11782-1:2008EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 11782-1 April 2008 ICS 77.060 English Version Corrosion o
5、f metals and alloys - 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 -
6、Teil 1: Prfung unter 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
7、standard without any 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 o
8、ther language made 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, Eston
9、ia, Finland, France, 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 EUROP
10、ISCHES KOMITEE FR NORMUNG 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: EForeword The text of ISO 11782-1:1998 has been prepared by Technical Committee
11、 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 coatings” the secretariat of which is held by BSI. This European Standard shall be g
12、iven 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. Attention is drawn to the possibility that some of the elements of this document m
13、ay 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 of the following countries are bound to implement this European Standard: Austri
14、a, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement
15、 notice The text of ISO 11782-1:1998 has been approved by CEN as a EN ISO 11782-1:2008 without any modification. BS EN ISO 11782-1:2008 iii Contents Page Introduction 1 1 Scope 1 2 Normative reference 1 3 Definitions 1 4 Test 2 4.1 Principle 2 4.2 Specimens 2 4.3 Environmental considerations 6 4.4 S
16、tressing considerations 7 5 Apparatus 7 6 Procedure 7 7 Test report 8 Annex A (informative) Bibliography 10 Figure 1 Schematic comparison of S-N behaviour during fatigue and corrosion fatigue for steel 4 Figure 2 Specimens with tangentially blending fillets between the test section and the ends 5 Fi
17、gure 3 Specimens with a continuous radius between ends 5 Figure 4 Specimens with tangentially blending fillets between the uniform test section and the ends 5 Figure 5 Specimens with a continuous radius between ends 6 Descriptors: Metal products, metals, alloys, corrosion, corrosion tests, fatigue t
18、ests, cyclic tests, breaking. BS EN ISO 11782-1:2008blank1 Introduction The study of cycles to failure testing uses plain or notched specimens to provide data on the intrinsic corrosion fatigue crack like behaviour of a metal or alloy and can be used to develop criteria for engineering design to pre
19、vent fatigue failures. The study of cycles to failure can be applied to a wide variety of product forms including plate, rod, wire, sheet and tubes as well as to parts joined by welding. The results of corrosion fatigue testing are suitable for direct application only when the service conditions exa
20、ctly parallel the test conditions especially with regard to material, environmental and stressing considerations. The combination of material/load/environmental may not be directly comparable to the application. For these cases engineering judgement must be applied. 1 Scope 1.1 This International St
21、andard provides guidance and instruction on corrosion fatigue testing of metals and alloys in aqueous or gaseous environments and is concerned with cycles to failure testing. Crack propagation testing is considered in ISO11782-2. 1.2 Corrosive or otherwise chemically active environments can promote
22、the initiation of fatigue cracks in metals and alloys and increase the rate of fatigue crack propagation. Corrosion fatigue processes are not limited to specific metal/environment systems and reliable estimates of fatigue life for all combinations of loading and environment cannot be made without da
23、ta from laboratory tests. 1.3 This International Standard is not intended for application to corrosion fatigue testing of components or parts; nevertheless many of the general principles will apply. 2 Normative reference The following standard contains provisions which, through reference in this tex
24、t, constitute provisions of this part of ISO11782. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this part of ISO11782 are encouraged to investigate the possibility of applying the most recent edition of the sta
25、ndard indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 7539-1:1987, Corrosion of metals and alloys Stress corrosion testing Part 1: General guidance on testing procedures. 3 Definitions For the purposes of this part of ISO11782, the following
26、 definitions apply. 3.1 corrosion fatigue process involving conjoint corrosion and alternating straining of the metal, often leading to cracking NOTECorrosion fatigue may occur when a metal is subjected to cyclic straining in a corrosive environment. 3.2 stress amplitude, S a , in fatigue loading on
27、e half of the range of a cycle (also known as the alternating stress): 3.3 mean stress, S m , in fatigue loading algebraic average of the maximum and minimum stresses in constant amplitude loading or of individual cycles in spectrum loading: 3.4 maximum stress, S max , in fatigue loading that stress
28、 having the highest algebraic value: S max= S m+ S a 3.5 minimum stress, S min , in fatigue loading that stress having the lowest algebraic value: S min = S m S a 3.6 stress ratio, R, in fatigue loading algebraic ratio of the minimum and maximum stress of a cycle: NOTEThe stress ratio, R, is equal t
29、o the load ratio P min /P max , where P minand P maxare the minimum and maximum loads in the cycle, respectively. 3.7 S-N diagram plot of stress against the number of cycles to failure the stress can be the maximum stress, S max , minimum stress, S min , stress range, %S or S r , or alternating stre
30、ss, S a . The diagram indicates the S-N relationship for a specified value of S m , R and a specified probability of survival. For N, a log scale is almost always used. For S, a linear scale or a log scale is used S a S max S min 2 - = S m S max S min + 2 - = R S min S max - = BS EN ISO 11782-1:2008
31、2 3.8 fatigue notch factor, K f ratio of the fatigue strength of a specimen with no stress concentrator to that of a specimen with a stress concentrator for the same percent survival at N cycles for the same loading and environmental conditions NOTEIn specifying K f , it is necessary to specify the
32、geometry and the values of stress amplitude, mean stress and N for which it is computed. 3.9 stress concentration factor, K t ratio of the greatest stress in the region of a notch or other stress concentrator as determined by the theory of elasticity to the corresponding nominal stress K tbecomes in
33、valid 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 terms fatigue cycle, load cycle and stress cycle are also commonly used 3.11 waveform shape of the peak-to-peak variati
34、on 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 cycles, S N value of stress for failure at exactly N load cycles as determined from an S-N diagram. The value of S Nthus dete
35、rmined is subject to the same conditions as those that apply to the S-N diagram NOTE 1The value of S Nis also known as the median fatigue strength for N cycles. NOTE 2In a corrosive environment the fatigue strength is likely to be reduced compared with that in air. 3.14 fatigue strength limit, S f l
36、imiting value of the median fatigue strength as the fatigue life, N, becomes very large. Most materials and environments preclude the attainment of well defined fatigue limits 4 Test 4.1 Principle In the presence of an aggressive environment the fatigue strength of a metal or alloy is reduced to an
37、extent which depends on the nature of the environment and the test conditions. For example, the well-defined fatigue strength limit observed for steels in air may no longer be evident as illustrated in Figure 1. Interpretation of results is then based on the assumption of an acceptable life of the c
38、omponent. The test involves subjecting a series of specimens to the number of stress cycles required for a fatigue crack to initiate and grow large enough to cause failure during exposure to a corrosive or otherwise chemically active environment at progressively smaller alternating stresses in order
39、 to define either the fatigue strength at N cycles, S N , from an S-N diagram or the fatigue strength limit as the fatigue life becomes very large. The test is used to determine the effect of environment, material, geometry, surface condition, stress, etc, on the corrosion fatigue resistance of meta
40、ls 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 for service under conditions of repeated applied stress under known environmental conditions. 4.2 Specimens 4.2.1 General The design and type of specime
41、n used depends on the fatigue testing machine used, the objective of the fatigue study and the form of the material from which the specimen is to be made. Fatigue test specimens are designed according to the mode of loading which can include axial stressing, plane bending, rotating beam, alternate t
42、orsion or combined stress. Specimens may have circular, square, rectangular, annular or, in special cases, other cross-sections. The gripped ends may be of any shape to suit the holders of the test machine. Problems may arise unless the gripped portion of the specimen is isolated from the corrosive
43、test environment. The test section of the specimen shall be reduced in cross-section to prevent failure in the grip ends and should be of such a size as to use the middle to upper ranges of the load rating of the fatigue machine to optimize the sensitivity and response of the system. BS EN ISO 11782
44、-1:20083 The transition from the gauge section to the gripped ends of the specimen shall be designed to minimize any stress concentration. It is recommended that the radius of the blending fillet shall be at least eight times the specimen test section diameter or width. The cross-sectional area of t
45、he gripped ends shall, where possible, be at least four times that of the test section area. The test section length shall be greater than three times the test section diameter or width. For tests run in compression, the length of the test section shall be less than four times the test section diame
46、ter or width in order to minimize buckling. For the purposes of calculating the load to be applied to obtain the required stress, the dimensions from which the area is calculated shall be measured to within0,02mm. Specimens shall be identified by an indelible marking method, such as stamping, on sur
47、face areas, preferably on the 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 to avoid corrosion which may influence the test results. 4.2.2 Cylindrical specimens Two types of spec
48、imens with circular cross-section are frequently used for corrosion fatigue tests: a) specimens with tangentially blending fillets between the test section and the grip ends (seeFigure 2); these are suitable where axial loading is employed; b) specimens with a continuous radius between the grip ends
49、 with the minimum diameter at the centre (see Figure 3); these are suitable for rotating bend tests. A minimum cross-section diameter of 5mm is preferred. 4.2.3 Flat sheet or plate specimens Flat specimens for fatigue tests are reduced in width in the test section and may have thickness reductions. If the specimen thickness is less than2,5mm, and the tests are perfo
