1、CEN EN*ISO*7384 95 3404589 009bLL5 028 BRITISH STANDARD I BS EN IS0 Corrosion tests in artificial atmospheres - General requirements The European Standard EN IS0 7384 : 1995 has the status of a British Standard 7384 : 1995 CEN EN*ISO*7384 95 m 3404589 00b11b Tb4 = Amd. No. The following WI reference
2、s relate to the work on this standard: Committee reference ISE/NFE/8 Draft announced in - the nature of the tested metais, alloys or means of cor- rosion protection (chemical composition, thickness, state of the specimen surface); - the method of test: operating conditions, total duration of the tes
3、t, position and eventually permutation of the test specimens, frequency of removal and examination of specimens during the test, number of specimens removed and number of control specimens; - the calibration of the corrosivity of the atmosphere of the test chamber regardless of specimen orientation
4、in the chamber; - the criteria and methods of evaluation of the test results. li At present at the stage of draft. Bge 4 EN IS0 7384 : 1995 4.3 The tests can be classified as follows: a) enhanced environment tests in which the conditions are chosen to duplicate the corrosion mechanism in service con
5、ditions, 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 which the corrosive en- vironment is chosen to produce accelerated corrosion. Tests of this ype allow comparison o
6、f corrosion resistance of similar corrosion protection if this has been shown to be vaid y practical experience for the specific environment: c) rapid quality control tests in which the corrosive en- vironment is chosen to produce abnormally accelerated cor- rosion. Tests of this type allow rapid de
7、termination of defects and weak points in the corrosion protection. fhe classification o a specific test is dependent on the material tested. 5 Requirements for test specimens 5.1 Inespective of the method used, all tests shall be camed Out using specimens treated or coated in the same way and havin
8、g tha 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 evektation of the test reculrc. lhe thickness of the test specimens shall be preferabiy between 0.5 and 3 mm; and in any cace,
9、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 results, may be used as test specimens. In order to exclude, as far as possible, the effect of irregularities the total surfa
10、ce area of the test specimen shall be as large as possible and not less than 25 cmz, except where smaller surface areas are specified in special test regulations. 5.3 specified in the test programme. The surface roughness of a test specimen shall be 5.4 The surface of test specimens of metals and al
11、loys shall be free from visible defects. such as scratches, inclusions, cracks, pits and porosity. Cut edges should have no bum. 5.5 The coatings of test specimens shall meet all the re- quirements of the appropriate International Standards, for example IS0 1456, IS0 1458, IS0 1461, IS0 2081, IS0 20
12、82. 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. 5.7 While preparing test specimens in which there is a welded joint, the joint shall be placed in the centre of the test sp
13、ecimen parallel to its longest side. 5.8 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
14、 influence of un- protected edges on the 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 specimen
15、s to be removed, shall be stored over the total period of testing under conditions which prevent corrosion. The con- ditions shall be specified in the fest 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
16、 specimens during the test, the number of tect 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 carr
17、ied Out in special chambers or cabinets which shall be large enough to assure homogeneous distribu- tion and unifomi 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 appara
18、tus shall maintain the specified operating 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 cond
19、ensation tests. The concentration of corrosive agents shall be recorded automatically or determined periodically. 6.4 testing different corrosive agents. It is not recommended to use the same chamber for 6.5 The testing of specimens protected with volatile in- hibitors shall be carried out in specia
20、l chambers intended for this purpose in which traces of volatile inhibitors from previous tests have been removed. 6.6 The inside surfaces of parts of chamben, gaskets for hatches and doors, communication equipment and apparatus, devices for testing the test specimens, which are in contact with corr
21、osive agents shall be made of materials that are resis- tant to the corrosive test atmosphere. 6.7 If necessary. a system of air circulation shall be installed in order to provide uniform operating conditions throughout the chamber. 6.8 increasing at a rate of at least 1 %/min upon startup. The temp
22、erature inside the chamber shall be capable of 6.9 be produced by means of a supply of humidified air. The specified relative humidity inside the chamber shall For humidification purposes, only distilled or deionized water shall be used. It is not permissible to produce the specified relative humidi
23、ty 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 the chamber shall be not more than 1 h. 6.11 The temperature and relative humidity inside the cham
24、ber shall be controlled to an accuracy of I 2 OC and f 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, temperature and humidity conditions of the supply of air to be used shall be as specified in th
25、e 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. Page 5 EN IS0 7384 : 1995 7.2.2 Specimens, the corrosion behaviour of which is to be evaluated
26、by a change in surface appearance, shall be exam ined in conformity with he 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 visible corrosion defects which are acceptable to the interested partie
27、s. 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 1W, with lines, which divide the specimen surface into squares of 5 mm x 5 mm, shall be put over the test specimen. Each s
28、quare 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 mass, the surface area of the specimen shall be measured, then the specimens
29、shalt 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 Mo g; - to an accuracy of 0.01 g for specimens with a mass over 200 g. 7.2.4 Other initial characteristics of the test specimens are dete
30、rmined 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 checking the distribution of the solution and the corresponding tolerances shall
31、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 checking and the tolerances shall be specified in the appropriate Internationa
32、l Standards. 7 Preparation of test specimens 7.1 Prior to testing the surface of the test specimens with and without metallic and other non-organic coatings shali be degreased using an inen product. Treatment of the specimens prior to testing 7.2 Examination of the specimens prior to testing 7.2.1 T
33、he 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- rosion before testing. 7.3.1 The test specimens shall be placed only in that zone
34、 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 parts of the chamber on to the specimens placed below. The samples should be
35、 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 specimens shall be placed vertically or at an angle of 1B to 30 to the vertical,
36、 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 in testing specimens where the welded joint is parallel to the bottom of the ch
37、amber. 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 bottom of the chamber being not less than 200 mm. CEN EN*IS0*7384 75 3404587 009bL24
38、 030 II Page 6 EN IS0 7384 : 1996 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
39、 be as small as possible. The fasteners shall not causegalvanic effects, or contamination of the specimens. 8 Procedure 8.1 Duration of tests 8.7.1 The total period of testing for each test method depends upon the purpuse of the test, nature of the tested metals, alloys and means of protection and t
40、he chosen criierion and method for evaluation of their corrosion behaviour. Recommendedperiodsof exposureare 24 h - 48 h - 96 h - 240 h - 480 h - 720 h - 2016 h. 8.72 The duration of the test shall be recorded from the mo- nmnt sgscimens are introduced into the chamber when all the specified operati
41、ng Conaitions are met. 8.14 The duration of forced interruptions as weil as the dura- tion of periodic examination and remaval 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 end i
42、n accordance with the test pro- gramme, all specimens shall be examined and some of them removad. 82.2 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 CO as to preve
43、nt damage to the specimen. 8.2.3 Upon completion of the exxposure 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 surf
44、aces after testing shall 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
45、 example: a) change in the specimen appearance during the test; b) time dapsed before the first local site of corrosion of base metal or coating appears; c) number and distribution of corrosion defects; di change in mass (see IS0 8407); e) change in dimensions (especially thickness); f) change in me
46、chanical, electric, 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, 85 well as on the purpose and the method of test. Use the m
47、ethods of evaluation 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 ch
48、emical composition of the corrosive environment and the test operating conditions; ci designation and description of the test specimen (chemical composition. shape and dimensions, method of treatment: chemical, thermal and mechanical; type of coating and its thickness); d) known characteristics of t
49、he specimen tested; el exposure period; f) duration of the tests and total number of test cycles; g) method of placing and material for fastening the test specimens during the test; h) the results of evaluation of corrosion changes for the tested specimen surfaces, including both descriptive and numerical assessment. possibly with photographs of the test specimens. Other data may be included in the test report depending on the purpose and method of test as well as on the criteria chosen for evaluating the results. Page 7 EN IS0 7384 : 1995 Annex ZA (normative) Normative references to
