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1、 Reference number ISO 24497-2:2007(E) ISO 2007 INTERNATIONAL STANDARD ISO 24497-2 First edition 2007-11-01 Non-destructive testing Metal magnetic memory Part 2: General requirements Essais non destructifs Mmoire magntique des mtaux Partie 2: Exigences gnrales Copyright International Organization for
2、 Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=Japan, IHS Not for Resale, 12/17/2007 19:57:21 MSTNo reproduction or networking permitted without license from IHS -,-,- ISO 24497-2:2007(E) PDF disclaimer This PDF file may contain embedded typefaces. In
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5、 printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2007 All rights reserved. Unless oth
6、erwise 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 the address below or ISOs member body in the country of the requester. ISO copyrig
7、ht office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2007 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Emplo
8、yees/1111111001, User=Japan, IHS Not for Resale, 12/17/2007 19:57:21 MSTNo reproduction or networking permitted without license from IHS -,-,- ISO 24497-2:2007(E) ISO 2007 All rights reserved iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national
9、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 subject for which a technical committee has been established has the right to be represented on that committee. International
10、 organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules g
11、iven in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at leas
12、t 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 24497-2 was prepared by the International Institute o
13、f Welding, Commission V, Quality control and quality assurance of welded products, recognized as an international standardizing body in the field of welding in accordance with Council Resolution 42/1999. Requests for official interpretations of any aspect of this part of ISO 24497 should be directed
14、 to the ISO Central Secretariat, who will forward them to the IIW Secretariat for an official response. ISO 24497 consists of the following parts, under the general title Non-destructive testing Metal magnetic memory: Part 1: Vocabulary Part 2: General requirements Part 3: Inspection of welded joint
15、s Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=Japan, IHS Not for Resale, 12/17/2007 19:57:21 MSTNo reproduction or networking permitted without license from IHS -,-,- Copyright International Organization for
16、Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=Japan, IHS Not for Resale, 12/17/2007 19:57:21 MSTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 24497-2:2007(E) ISO 2007 All rights reserved 1 Non-destru
17、ctive testing Metal magnetic memory Part 2: General requirements 1 Scope This part of ISO 24497 specifies the general requirements for the application of the method of metal magnetic memory of components, units, equipment, and structures for various application purposes. It covers non-destructive te
18、sting. The purposes of the method are the following. Determination of heterogeneity of the stress/strain state of equipment and structures and revealing of stress concentration zones as the main sources of damage. Determination of locations to perform metal sampling in stress concentration zones for
19、 assessment of the microstructural-mechanical state. Early diagnostics of fatigue damage and evaluation of equipment and structure life. Reduction of testing and material costs with its utilization in combination with conventional methods of non-destructive testing. Quality control of welded joints
20、of various types and embodiment (including contact and spot welding). Very quick sorting of new and used machine-building products by their microstructural heterogeneity. 2 Abbreviated terms The following abbreviations are used in this part of ISO 24497: IO: Inspection Object; SMLF: Self-Magnetic-Le
21、akage Field; MMM: Metal Magnetic Memory; NDT: Non-Destructive Testing; SCZ: Stress Concentration Zone. NOTE The Stress Concentration Zone (SCZ) is characterized by an abrupt local change of magnetization in the test object. Under examination SCZ is indicated as an abrupt local change of the SMLF. SC
22、Z is formed in places of defect concentration, heterogeneity of metal microstructure; i.e., along welded joints or in zones of steady dislocation slip band caused by static or cyclic loads. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS E
23、mployees/1111111001, User=Japan, IHS Not for Resale, 12/17/2007 19:57:21 MSTNo reproduction or networking permitted without license from IHS -,-,- ISO 24497-2:2007(E) 2 ISO 2007 All rights reserved 3 General information 3.1 The MMM method refers to non-destructive magnetic-flux leakage testing by us
24、ing magnetic-field- sensitive probes, but with no active magnetization of the IO. 3.2 The MMM method is based on measurement and analysis of the distribution of self-magnetic-leakage fields of metal components. Self-magnetic-leakage fields reflect the microstructural and technological history of met
25、al components, including welded joints. Natural magnetization formed in the Earths magnetic field during the process of the product fabrication is used during testing. For the equipment in operation, the magnetic memory appears in the irreversible change of the magnetization of the material in the d
26、irection of maximal stresses due to working loads. 3.3 The MMM method determines SCZ, presence of imperfections, and heterogeneity of metal and welded joints microstructures. NOTE For components and machine-building products, SCZ in metal is conditioned by the technology of their fabrication (fusion
27、, forging, rolling, turning, press forming, thermal treatment, etc.). 3.4 For operating equipment in service, the MMM method gives the definition of SCZ specified by the complex action of technological factors, the units design philosophy, and operating loads. 3.5 The MMM method is used on products
28、made of ferromagnetic and austenitic steels and alloys, and cast iron with unlimited test sizes and thicknesses, including welded joints. NOTE Austenitic steels can be inspected if their microstructure is sensitive for phase transformation under static or cyclic loads. 3.6 The temperature range of t
29、he MMM method application is according to the normal and safe working conditions of the operator (NDT inspector). Inspection tools shall be operable at temperatures from 20 C to +60 C. 4 Requirements of the inspection object 4.1 During the application of the MMM method, equipment and structures are
30、inspected both in the in-service state (under load) and during maintenance (after removal of operating loads). 4.2 Surface dressing and preparation are not required. It is recommended to remove insulation. In individual cases, non-magnetic insulation is allowed during inspection. The maximum permiss
31、ible insulation layer thickness shall be determined experimentally. 4.3 The range of metal thicknesses in inspection zones is specified in techniques used for this inspection object. 4.4 The limiting factors for the application of the MMM method are the following: artificial magnetization of the met
32、al; influence of foreign ferromagnetic products on the inspection object, near the inspection region of interest; presence of the source of an external magnetic field or an electric-welding current flow near (closer than 1 m) to the IO. 4.5 Acoustic noise from the IO and mechanical vibration of the
33、IO do not influence the inspection results. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=Japan, IHS Not for Resale, 12/17/2007 19:57:21 MSTNo reproduction or networking permitted without license from IHS -,-,-
34、 ISO 24497-2:2007(E) ISO 2007 All rights reserved 3 5 Requirements of the inspection means 5.1 For equipment inspection using the MMM method, specialized magnetometric instruments are used. The typical technique of the SCZ determination shall be documented in the manual of the instruments mentioned.
35、 5.2 The principle of the operation of these instruments is based on the registration of induced electrical voltage pulses in the sensor coil of a flux-gate meter at its placement into the self-magnetic-leakage field (SMLF) of the near-surface area of the IO. A flux-gate meter or other magnetic-sens
36、itive transformers (field meters or gradiometers) can be used as sensors for measuring the SMLF intensity. 5.3 Instruments shall have a screen for the graphical representation of the inspection parameters, a recorder based on a microprocessor, a storage unit, and scanner assemblies depending on the
37、form of the individual specialized sensors. The possibility of an information swap from the instrument to an external computer and data printout shall be provided. Special software for computer processing of the inspection results should be supplied with the instrument. 5.4 Specialized sensors are s
38、upplied with the instrument. The sensor type is determined by the method and the specific inspection tasks. The sensor shall have not less than two measurement channels, one of them for the instrument and another for tuning out the influences of the Earths external magnetic field. 5.5 The sensor hou
39、sing shall be equipped with an electronic unit for the measured field amplification and a sensor for measuring the length of the scanned inspection path length. 5.6 On the IO, where it is difficult to use scanning devices, it is permitted to apply magnetometric instruments with a digital display of
40、the magnetic field intensity. 5.7 The following factors influence the error of SMLF measurements: IO surface finish; sensor lift-off from the IO surface; sensor scanning rate along the IO surface; sensor sensitivity; the permissible error of measurement shall be indicated in the techniques depending
41、 on the individual inspection object. 5.8 The instruments should have the following metrological characteristics: the relative error of the measured magnetic field for each instrument channel not more than 5 %; the error of the measured length not more than 5 %; instrument measurement range not less
42、 than 1 000 A/m; minimal scanning step (distance between the two adjacent inspection points) of 1 mm; electronic noise level conditioned by the processor and operation of the micro-electronics not more than 5 A/m. Copyright International Organization for Standardization Provided by IHS under license
43、 with ISO Licensee=IHS Employees/1111111001, User=Japan, IHS Not for Resale, 12/17/2007 19:57:21 MSTNo reproduction or networking permitted without license from IHS -,-,- ISO 24497-2:2007(E) 4 ISO 2007 All rights reserved 6 Pre-testing procedure 6.1 The pre-testing procedure is part of the following
44、 basic stages: analysis of the technical documentation of the IO and preparation of the IO chart (logfile, inspection plan); selection of sensors and test instrument types; setting and calibration of the instruments and sensors according to the instruction indicated in the manual; segmentation of th
45、e inspection object into individual inspection areas and inspection units having their own design philosophy and their indication in the IO logfile. 6.2 Analysis of technical documentation for the inspection object includes the following: indication of the steel grades and the dimensions of the sele
46、cted inspection units; analysis of the IO operation modes and reasons of failures (damages); indication of the inspection units design philosophy, and locations of welded joints. 7 Inspection procedure 7.1 The normal and/or tangential component of the self-magnetic-leakage field, Hp, is measured at
47、the IO surface by continuous or spot scanning with the instrument sensor. At the same time, positions with extreme Hp field changes are determined and registered at the IO surface. The zero value of the normal component corresponds to the maximal value of the tangential component of the field. 7.2 F
48、or quantitative assessment of the residual stress concentration level, the coefficient, Kin, indicating the intensity of the normal and/or tangential component of the magnetic field gradient, is determined by the formula: p in K H K l =, A/m2 (1) where Hp is the difference of the Hp fields between the two adjacent scanning points; lK is the distance between these adjacent points. The zone of maximal concentration of residual stress corresponds to the