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1、Reference number ISO 7539-8:2000(E) ISO 2000 INTERNATIONAL STANDARD ISO 7539-8 First edition 2000-07-01 Corrosion of metals and alloys Stress corrosion testing Part 8: Preparation and use of specimens to evaluate weldments Corrosion des mtaux et alliages Essais de corrosion sous contrainte Partie 8:
2、 Prparation et utilisation des prouvettes pour valuer les assemblages souds Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 00:28:33 MDTNo reproduction or networking permitted wi
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6、l Secretariat at the address given below. ISO 2000 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at
7、the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 ? CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch Printed in Switzerland ii ISO 2000 All rights reserved Copyright International Organizati
8、on for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 00:28:33 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 7539-8:2000(E) ISO 2000 All rights reservediii ContentsPage Foreword.iv 1Scop
9、e 1 2Normative references1 3Terms and definitions .2 4Special considerations for weldments3 5Specimen types4 6Preparation of weldments and test specimens8 7Testing Procedures .10 8Assessment11 9Test report11 Annex A (informative) Terms and definitions which have not been internationally agreed .13 B
10、ibliography18 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 00:28:33 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 7539-8:2000(E) iv ISO 2000 Al
11、l rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a sub
12、ject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (I
13、EC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an Intern
14、ational Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this part of ISO 7539 may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Inte
15、rnational Standard ISO 7539-8 was prepared by Technical Committee ISO/TC 156, Corrosion of metals and alloys. ISO 7539 consists of the following parts, under the general title Corrosion of metals and alloys Stress corrosion testing: ?Part 1: General guidance on testing procedures ?Part 2: Preparatio
16、n and use of bent-beam specimens ?Part 3: Preparation and use of U-bend specimens ?Part 4: Preparation and use of uniaxially loaded tension specimens ?Part 5: Preparation and use of C-ring specimens ?Part 6: Preparation and use of pre-cracked specimens ?Part 7: Slow strain rate testing ?Part 8: Prep
17、aration and use of specimens to evaluate weldments ?Part 9: Preparation and use of pre-cracked specimens for tests under rising load or rising displacement Annex A of this part of ISO 7539 is for information only. Copyright International Organization for Standardization Provided by IHS under license
18、 with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 00:28:33 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARDISO 7539-8:2000(E) ISO 2000 All rights reserved1 Corrosion of metals and alloys Stress corrosion testing Part 8
19、: Preparation and use of specimens to evaluate weldments 1Scope This part of ISO 7539 covers the procedures available for stress corrosion testing of welded specimens and examines the additional factors which must be taken into account when conducting tests on welded specimens. In particular this pa
20、rt of ISO 7539 gives recommendations for the choice of specimens and test procedures to determine the resistance of a metal to stress corrosion when it is welded. The term “metal”, as used in this part of ISO 7539, includes alloys. 2Normative references The following normative documents contain prov
21、isions which, through reference in this text, constitute provisions of this part of ISO 7539. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of ISO 7539 are encouraged to investigate the possi
22、bility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 857-1:1998, Welding and allied p
23、rocesses Vocabulary Part 1: Metal welding processes. ISO 7539-2:1989, Corrosion of metals and alloys Stress corrosion testing Part 2: Preparation and use of bent-beam specimens. ISO 7539-3:1989, Corrosion of metals and alloys Stress corrosion testing Part 3: Preparation and use of U-bend specimens.
24、ISO 7539-4:1989, Corrosion of metals and alloys Stress corrosion testing Part 4: Preparation and use of uniaxially loaded tension specimens. ISO 7539-5:1989, Corrosion of metals and alloys Stress corrosion testing Part 5: Preparation and use of C-ring specimens. ISO 7539-6:1), Corrosion of metals an
25、d alloys Stress corrosion testing Part 6: Preparation and use of pre- cracked specimens. ISO 7539-7:1989, Corrosion of metals and alloys Stress corrosion testing Part 7: Slow strain rate testing. IEC 60050-851 (1991-08), International Electrotechnical Vocabulary Chapter 851: Electric Welding. 1)To b
26、e published. (Revision of ISO 7539-6:1989) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 00:28:33 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO
27、7539-8:2000(E) 2 ISO 2000 All rights reserved 3Terms and definitions For the purposes of this part of ISO 7539 the following terms and definitions apply. 3.1 welding operation which unites materials by means of heat or pressure, or both, in such a way that there is continuity in the nature of the ma
28、terials which have been joined and in which filler metal, the melting temperature of which is of the same order as that of the parent metal(s), may or may not be used NOTEThis definition also includes surfacing. ISO 857-1 3.1.1 fusion welding welding involving localized melting without the applicati
29、on of force and with or without the addition of filler metal ISO 857-1 3.1.2 arc welding fusion welding in which heat for welding is obtained from an electric arc or arcs ISO 857-1; IEC 60050-851 3.1.3 diffusion welding pressure welding in which the workpieces are kept in contact under a specified c
30、ontinual pressure and are heated, either on their faying surfaces or in their entirety, at a defined temperature for a controlled time NOTE 1This process results in local plastic deformation and also, owing to the very close contact between the surfaces, the diffusion of the atoms through the interf
31、ace. The end result is thus complete continuity of the material. NOTE 2The operation may take place in a vacuum, under a gas shield or in a fluid, preferably without the addition of a filler metal. See Figure 1. ISO 857-1 Copyright International Organization for Standardization Provided by IHS under
32、 license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 00:28:33 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 7539-8:2000(E) ISO 2000 All rights reserved3 Key 1Induction heating element 2Work chamber 3Workpiece 4Weld Figure 1 Diffu
33、sion welding 3.2 arc voltage voltage across the arc, including the anode and cathode voltage drop, measured as near as possible to the arc IEC 60050-851 See annex A. 4Special considerations for weldments 4.1General The factors given in this clause may all influence the corrosion and/or mechanical pr
34、operties of a weldment relative to that of the parent metal and their effects may require consideration in stress corrosion test procedures. Whilst the considerations listed below are relevant to the more common fusion welding processes, similar consideration shall also be given to solid phase (non-
35、fusion) welding processes and diffusion welding. Weld regions are more likely than the parent metal to contain defects which may influence corrosion and stress corrosion behaviour, e.g. microcracking, lack of fusion and porosity. For this reason, examination of the weld shall be undertaken to assess
36、 whether the failure of any specimen is the result of pre-existing defects rather than stress corrosion. It is recommended that the weldment be characterized with regard to residual welding stresses, surface condition and weld defects prior to testing. See clause 7. 4.2Changes in microstructure In f
37、usion welding, the application of heat to a parent metal produces microstructural changes in the heat affected zone (HAZ) of the parent metal adjacent to the weld junction. A rapidly-cooled weld metal differs microstructurally Copyright International Organization for Standardization Provided by IHS
38、under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 00:28:33 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 7539-8:2000(E) 4 ISO 2000 All rights reserved and chemically from the parent metal and is more typical of a cast str
39、ucture. These differences may influence both weldment corrosion and mechanical properties, as well as susceptibility to stress corrosion cracking. Some alloys such as C-Mn steels display a visible HAZ. However, in some alloys, welding may also produce precipitation and segregation effects within the
40、 parent metal remote from the visible HAZ. 4.3Non-metallic inclusions In addition to changes in chemical composition, the welding procedure and conditions used may result in a weld metal with a non-metallic inclusion content and distribution different from that of the parent metal. This may influenc
41、e weldment corrosion and stress corrosion cracking behaviour. 4.4Stress concentration effects Shrinkage stresses following welding will introduce residual welding stresses which will be both transverse and longitudinal with respect to the welding direction (and through thickness in thick-walled samp
42、les). Tensile stresses are usually generated at the weld, with balancing compressive stresses in the parent metal. In addition, weld geometry may cause further stress concentration effects. 5Specimen types 5.1General The design and type of specimen used depend on the form of the metal from which the
43、 specimen is to be made and on the objective of the test. The test specimens described in ISO 7539 parts 2-7 are suitable for tests on weldments, subject to the additional considerations presented in this part of ISO 7539. In addition, a number of other types of specimens, as described in 5.2.1 to 5
44、.2.8 below, can be used. Specimens can be prepared from weldments in the as-welded or post-weld heat-treated conditions. It is recommended that specimens be tested in the same condition of heat treatment as that of the intended application. 5.2Types of specimen 5.2.1Flat weldment See Figure 2. This
45、type of weldment is applicable for all tension and bend specimens and for any welding procedure whether involving single- or multi-pass welds. The weldment may also be used to evaluate the effect of residual welding stresses. 5.2.2Circular bead weldment See Figure 3. The welding procedure involves o
46、ne circular bead deposit of weld metal. The circular weld develops residual welding stresses. It is applicable to any material form that can be machined to the recommended size as specified in Figure 3. Copyright International Organization for Standardization Provided by IHS under license with ISO L
47、icensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 00:28:33 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 7539-8:2000(E) ISO 2000 All rights reserved5 5.2.3Bead-on-bar weldment See Figure 4. The longitudinal fusion welds at diametrically opposite
48、 positions on the bar develop residual welding stresses in the bar. Hence, this weldment can be used to evaluate the tendency for stress corrosion cracking of the parent metal. It is applicable to materials that can be machined to approximately 25 mm diameter. 5.2.4Direct tension specimen See Figure 5. This specimen type is stressed in uniaxially loaded tension (see ISO 7539-4 and ISO 7539-7). Notches, with or without pre-cracks, may be introduced