隙间腐蚀检测标准

隙间腐蚀检测标准相关信息

ASTM G48-2011 用氯化铁溶液测试不锈钢和相关合金抗点蚀和隙间腐蚀性能的标准试验方法
简介：These test methods describe laboratory tests for comparing the resistance of stainless steels and related alloys to the initiation of pitting and crevice corrosion. The results may be used for ranking alloys in order of increasing resistance to pitting and crevice corrosion initiation under the specific conditions of these methods. Methods A and B are designed to cause the breakdown of Type 304 at room temperature. The use of ferric chloride solutions is justified because it is related to, but not the same as, that within a pit or crevice site on a ferrous alloy in chloride bearing environments (1, 2). The presence of an inert crevice former of consistent dimension on a surface is regarded as sufficient specification of crevice geometry to assess relative crevice corrosion susceptibility. The relative performance of alloys in ferric chloride solution tests has been correlated to performance in certain real environments, such as natural seawater at ambient temperature (3) and strongly oxidizing, low pH, chloride containing environments (4), but several exceptions have been reported (4-7). Methods A, B, C, D, E, and F can be used to rank the relative resistance of stainless steels and nickel base alloys to pitting and crevice corrosion in chloride-containing environments. No statement can be made about resistance of alloys in environments that do not contain chlorides. Methods A, B, C, D, E, and F were designed to accelerate the time to initiate localized corrosion relative to most natural environments. Consequently, the degree of corrosion damage that occurs during testing will generally be greater than that in natural environments in any similar time period. No statement regarding localized corrosion propagation can be made based on the results of Methods A, B, C, D, E or F. Surface preparation can significantly influence results. Therefore, grinding and pickling of the specimen will mean that the results may not be representative of the conditions of the actual piece from which the sample was taken. Note 18212;Grinding or pickling on stainless steel surfaces may destroy the passive layer. A 24-h air passivation after grinding or pickling is sufficient to minimize these differences (8). The procedures in Methods C, D, E and F for measuring critical pitting corrosion temperature and critical crevice corrosion temperature have no bias because the values are defined only in terms of these test methods. Note 28212;When testing as-welded, cylindrical, or other non-flat samples, the standard crevice formers will not provide uniform contact. The use of contoured crevice formers may be considered in such situations, but the use of a pitting test (Practices A, C, or E) should be considered.1.1 These test methods cover procedures for the determination of the resistance of stainless steels and related alloys to pitting and crevice corrosion (see Terminology G15) when exposed to oxidizing chloride environments. Six procedures are described and identified as Methods A, B, C, D, E, and F. 1.1.1 Method A8212;Ferric chloride pitting test. 1.1.2 Method B8212;Ferric chloride crevice test. 1.1.3 Method C8212;Critical pitting temperature test for nickel-base and chromium-bearing alloys. 1.1.4 Method D821......
信息：ICS：77.060 (Corrosion of metals) CCS：H25 发布：2011 实施：