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1、International Standard INTERNATIONAL ORGANIZATION FOR STANDARDlZATION.MEYHAPOHAR OPrAHM3AUMR I-IO CTAHAAPTH3AUCIH.ORGANlSATlON INTERNATIONALE DE NORMALISATION Corrosion tests in artificial atmosphere - General requirements Essais de corrosion en atmosph - the nature of the tested metals, alloys or m
2、eans of cor- rosion protection (chemical composition, thickness, state of the specimen surface); - the method of test: operating conditions, total duration of the test, position and eventually permutation of the test specimens, frequency of removal and examination of specimens during the test, numbe
3、r of specimens removed and number of control specimens; - the calibration of the corrosivity of the atmosphere of the test chamber regardless of specimen orientation in the chamber; - the criteria and methods of evaluation of the test results. 1) At present at the stage of draft. 1 Copyright Interna
4、tional Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 21:54:20 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 73841986 (El 4.3 The tests can be classified as follows: a)
5、enhanced environment tests in which the conditions are chosen to duplicate the corrosion mechanism in service conditions, but at an accelerated rate. Tests of this type allow the prediction of long-term corrosion of metals, alloys and means of corrosion protection; b) short-term corrosion tests in w
6、hich the corrosive en- vironment is chosen to produce accelerated corrosion. Tests of this type allow comparison of corrosion resistance of similar corrosion protection if this has been shown to be valid by practical experience for the specific environment; c) rapid quality control tests in which th
7、e corrosive en- vironment is chosen to produce abnormally accelerated cor- rosion. Tests of this type allow rapid determination of defects and weak points in the corrosion protection. The classification of a specific test is dependent on the material tested. 5 5.1 out Requirements for test specimens
8、 Irrespective of the method used, all tests shall be carried using specimens treated or coated in the same way and having the same shape, dimensions and surface roughness. 5.2 The shape and dimensions of the test specimens shall be chosen according to the test method, criteria and methods of evaluat
9、ion of the test results. The thickness of the test specimens shall be preferably between 0,5 and 3 mm; and in any case, be such that they are not deformed during the test. If necessary, production articles or their parts with shapes which do not cause difficulties in the evaluation of the test resul
10、ts, may be used as test specimens. In order to exclude, as far as possible, the effect of irregularities the total surface area of the test specimen shall be as large as possible and not less than 25 cm2, except where smaller surface areas are specified in special test regulations. 5.3 The surface r
11、oughness of a test specimen shall be specified in the test programme. 5.4 The surface of test specimens of metals and alloys shall be free from visible defects, such as scratches, inclusions, cracks, pits and porosity, Cut edges should have no burrs. 5.5 The coatings of test specimens shall meet all
12、 the re- quirements of the appropriate International Standards, for example IS0 1456, IS0 1458, IS0 1461, IS0 2081, IS0 2082. 5.6 If test specimens are cut from a larger coated article, the cutting shall be carried out in such a way as to limit the amount of damage in the area adjacent to the cut. 5
13、.7 While preparing test specimens in which there is a 6.7 If necessary, a system of air circulation shall be installed welded joint, the joint shall be placed in the centre of the test in order to provide uniform operating conditions throughout specimen parallel to its longest side. the chamber. 2 5
14、.8 The cut edges of the test specimens shall be protected with a suitable coating stable in the chosen corrosive environ- ment; the coating used during testing may be, for example, paint, varnish, wax, tape or enamel. Cut edges shall be left unprotected when the influence of un- protected :dges on t
15、he corrosion is to be examined. 5.9 The test specimens should be identified. Marking shall be legible and durable over the whole period of testing and shall not have an effect on the test results. 5.10 Control specimens, intended for comparison with the specimens to be removed, shall be stored over
16、the total period of testing under conditions which prevent corrosion. The con- ditions shall be specified in the test programme. 5.11 The number of test specimens required is governed by the total duration of the test, the frequency of removal and examination of specimens during the test, the number
17、 of test specimens tested and the number of control specimens specified in the test programme. 5.12 The number of replicate specimens shall be not fewer than three; there shall be at least one control specimen. 6 Requirements for apparatus 6.1 The tests are carried out in special chambers or cabinet
18、s which shall be large enough to assure homogeneous distribu- tion and uniform conditions. The upper parts of the chambers shall be so shaped that drops of moisture or sprayed solution accumulated on them do not fall on the specimens being tested. 6.2 The apparatus shall maintain the specified opera
19、ting con- ditions within the exposure zone of the chamber for the com- plete duration of the test. 6.3 The specified operating conditions shall be controlled. Values of temperature and relative humidity shall be recorded automatically, except in the case of condensation tests. The concentration of c
20、orrosive agents shall be recorded automatically or determined periodically. 6.4 It is not recommended to use the same chamber for testing different corrosive agents. 6.5 The testing of specimens protected with volatile in- hibitors shall be carried out in special chambers intended for this purpose i
21、n which traces of volatile inhibitors from previous tests have been removed. 6.6 The inside surfaces of parts of chambers, gaskets for hatches and doors, communication equipment and apparatus, devices for testing the test specimens, which are in contact with corrosive agents shall be made of materia
22、ls that are resis- tant to the corrosive test atmosphere. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 21:54:20 MDTNo reproduction or networking permitted without license from
23、 IHS -,-,- IS0 7384-1986 (E) 6.8 The temperature inside the chamber shall be capable of increasing at a rate of at least 1 Y/min upon startup. 6.9 The specified relative humidity inside the chamber shall be produced by means of a supply of humidified air. For humidification purposes, only distilled
24、or deionized water shall be used. It is not permissible to produce the specified relative humidity inside the chamber by means of salt solutions, as these may influence the corrosion state of the test specimens. 6.10 The time required, from startup, to reach the specified relative humidity inside th
25、e chamber shall be not more than 1 h. 6.11 The temperature and relative humidity inside the chamber shall be controlled to an accuracy of f 2 “C and + 5 % respectively. 6.12 If the atmosphere is obtained by spraying a solution, as described in IS0 3768, IS0 3769, IS0 3770 and IS0 4536, the pressure,
26、 temperature and humidity conditions of the supply of air to be used shall be as specified in the appropriate Inter- national Standard. The supply of air used for spraying shall be free from all traces of oil or solid matter. If necessary the composition of the sprayed solution should be determined.
27、 7.2.2 Specimens, the corrosion behaviour of which is to be evaluated by a change in surface appearance, shall be exam- ined in conformity with the requirements of 5.3 to 5.5. The following changes in surface appearance shall be record- ed: colour, tarnishing of surface, presence and distribution of
28、 visible corrosion defects which are acceptable to the interested parties. For determination of the number and distribution of the defects, a wire screen of flexible transparent material, for example, plastic in conformity with that described in IS0 1462, with lines, which divide the specimen surfac
29、e into squares of 5 mm x 5 mm, shall be put over the test specimen. Each square shall be numbered counting from the top left hand corner. The results of the examinations shall be recorded for both sides of each specimen separately. 7.2.3 When corrosion behaviour is to be evaluated by a change in mas
30、s, the surface area of the specimen shall be measured, then the specimens shall be conditioned in a desic- cator containing a suitable desiccant for at least 24 h and weighed : - to an accuracy of 0,001 g for specimens with a mass up to 200 g; - to an accuracy of 0,Ol g for specimens with a mass ove
31、r 200 g. 7.2.4 Other initial characteristics of the test specimens are determined depending on the chosen criteria for evaluation of test results. The solution shall be uniformly distributed throughout the volume of the chamber. 7.3 Placing of the test specimens in the chamber The methods for checki
32、ng the distribution of the solution and the corresponding tolerances shall be as specified in the ap- propriate International Standards. 6.13 When a gaseous corrosive agent is used (for example sulfur dioxide) the concentration and flux uniformity in the chamber shall be checked. The methods for che
33、cking and the tolerances shall be specified in the appropriate International Standards. 7 Preparation of test specimens 7.1 Treatment of the specimens prior to testing Prior to testing the surface of the test specimens with and without metallic and other non-organic coatings shall be degreased using
34、 an inert product. 7.2 Examination of the specimens prior to testing 7.2.1 The specimens shall be examined prior to testing. Specimens intended for temporary corrosion protection shall be examined before application of the coating. Test specimens that have been stored shall be checked for cor- rosio
35、n before testing. 7.3.1 The test specimens shall be placed only in that zone of the chamber where the corrosive environment meets the re- quirement of all the specified parameters of the test conditions. Condensate and test solution shall not be permitted to trickle down from the specimens or upper
36、parts of the chamber on to the specimens placed below. The samples should be arranged in such a way that they cannot protect each other against the influence of the environment. The total area of the specimens shall not exceed 0,75 m2 per cubic metre of the volume of the chamber. ,7.3.2 The test spe
37、cimens shall be placed vertically or at an angle of 15O to 30 to the vertical, depending on the test method. In the case of specimens in which there is a welded joint, the joint shall be placed perpendicular or at an angle of 15O to 30” to the bottom of the chamber. There might also be an advantage
38、in testing specimens where the welded joint is parallel to the bottom of the chamber. Stain- ing from corrosion of the weld would then produce enhanced local corrosivity. The distance between the specimens shall be not less than 20 mm; the distance from the lowest edges of the specimens to the botto
39、m of the chamber being not less than 200 mm. 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 21:54:20 MDTNo reproduction or networking permitted without license from IHS -,-,-
40、IS0 7364-1966 (E) 7.3.3 Devices for fastening the test specimens shall be made from an inert material and shall provide adequate immobiliz- ation of the specimens, taking account of the conditions of test. The surface area of contact between the test specimens and their holders shall be as small as
41、possible. The fasteners shall not cause galvanic effects, or contamination of the specimens. 8 Procedure 8.1 Duration of tests 8.1.1 The total period of testing for each test method depends upon the purpose of the test, nature of the tested metals, alloys and means of protection and the chosen crite
42、rion and method for evaluation of their corrosion behaviour. Recommended periods of exposure are 24 h - 46 h - 96 h - 24Oh-46Oh-720h-2016h. 8.1.2 The duration of the test shall be recorded from the mo- ment specimens are introduced into the chamber when all the specified operating conditions are met
43、. 8.1.3 The duration of forced interruptions as well as the dura- tion of periodic examination and removal of the specimens shall not be included in the exposure period of the tests. 8.2 Frequency of removal and examination of specimens during the test 8.2.1 During the test and in accordance with th
44、e test pro- gramme, all specimens shall be examined and some of them removed. 8.2.2 During the periodic examinations, the test specimens shall be taken from.the chamber, examined and replaced for further testing. The examination of the specimens shall be carried out so as to prevent damage to the sp
45、ecimen. 8.2.3 Upon completion of the exposure the specimens tested shall be stored under conditions that exclude the beginning and further development of corrosion, in a desiccator containing a desiccant. 8.3 Surface treatment after testing The treatment of the test specimen surfaces after testing s
46、hall be carried out in accordance with the chosen criteria for the evaluation of the test results as given in 9.1. 9 Evaluation of test results 9.1 There are many criteria for the evaluation of corrosion resistance of metals and alloys with and without corrosion pro- tection, for example : a) change
47、 in the specimen appearance during the test; b) time elapsed before the first local site of corrosion of base metal or coating appears; c) number and distribution of corrosion defects; d) change in mass (see IS0 8407); e) change in dimensions (especially thickness) ; f) change in mechanical, electri
48、c, optical and other proper- ties. 9.2 The evaluation of the test results shall be carried out in accordance with the criteria chosen, depending on the re- quirements for the tested metals, alloys and means of protec- tion, as well as on the purpose and the method of test. Use the methods of evaluat
49、ion given either in appropriate Inter- national Standards, if any, for example IS0 1462, IS0 4540, IS0 4623, or in the test programme. 10 Test report The test report shall contain the following information: a) the purpose of the test; b) the test method, with an indication of the chemical composition of the corrosive environment and the test operating conditions; c) designation and description of the test specimen (chemical composition, shape and dimensions, method of t