ASTM G_Laboratory Immersion Corrosion Testing of Metals – Free download as PDF File .pdf), Text File .txt) or read online for free. ASTM G Other ASTM procedures for laboratory corrosion tests are tabulated in the Appendix. NOTE 1—Warning: In many cases the corrosion product on the reac-. ASTM G Standard Practice for Laboratory Immersion Corrosion Testing of Metals_能源/化工_工程科技_专业资料. 暂无评价|0人阅读|0次.
It should be appreciated that pitting is a statistical phenomenon and that the incidence of pitting may be directly related to the area of metal exposed. This can be done by chemical treatment picklingelectrolytic removal, or by grinding with a aastm abrasive paper or cloth such as No. This cracking occurs under conditions of applied or residual tensile stress, and it may or may not be visible to the unaided eye or upon casual inspection.
The use of towels for drying may introduce an error through contamination of the specimens with ashm or lint. These factors adtm specimen preparation, apparatus, test conditions, methods of cleaning specimens, evaluation of results, and calculation and reporting of corrosion rates. The mass loss during the test period can be used as the principal measure of corrosion. The most common testing periods are 48 to h 2 to 7 days.
Solvents such as acetone, carbon tetrachloride, and alcohol are used to remove oil, grease, or resin and are usually applied prior to other methods of cleaning. G 31 — 72 The others are used principally as a supplement to remove heavily encrusted corrosion products before scrubbing.
Preferably, the use of a re? Close attention and a more sophisticated evaluation than a simple mass loss measurement are required to detect this aetm.
Scrubbing with a bristle brush and mild abrasive is the most popular of these methods. A liquid atmospheric seal is required on the test vessel to prevent further contamination. In practice, only alloys of the same general type should be exposed in the testing apparatus. A number in parentheses indicates the year of last reapproval. For other 3g1 of adtm, the solution should be sparaged with air or synthetic mixtures of air or oxygen with an inert gas.
Last previous edition approved in as G 31 — 72 However, the absence of cracking should not be interpreted as indicating resistance see 4. Warning- In many cases the corrosion product on the reactive metals titanium and zirconium is a hard and tightly bonded oxide that defies removal by chemical or ordinary mechanical means.
Immersion Corrosion Testing According to ASTM G31 Standard
Circular specimens should preferably be cut from sheet and not bar stock, to minimize the exposed end grain. Location of deposits, variations in types of deposits, or variations in corrosion products are extremely important in evaluating localized corrosion, such as pitting and concentration cell attack. If metallic contamination of the stamped area may in? Link to Active This link will always route to the current Active version of the standard. This standard, rather than a satm procedure, is presented as a guide so that some of the pitfalls of such testing may be avoided.
Other procedures that require the removal of solid corrosion products between exposure periods will not measure accurately the normal changes of corrosion with time. The choice of a speci? Extraneous effects can be encountered if the air stream impinges on the specimens. However, the calculations must not be based on mass loss except in quali? If clad alloy specimens are to be used, special attention must be given to ensure that excessive metal is not removed.
The density in the constant K cancels out the density in the corrosion rate equation. There are a number of other special types of phenomena of which one must be aware in the design and interpretation of corrosion tests. Consequently, tests run for long periods are considerably more realistic than those conducted for short durations.
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. The values given in parentheses are for information only. However, there are cases where this assumption is not valid. Duplicate strips of low-carbon steel, each 19 by 76 mm 3?
Most tests related to process equipment should be run with the natural atmosphere inherent in the process, such as the vapors of the boiling liquid. This resurfacing may cause some surface work hardening, to an extent which will be determined by the vigor of the surfacing operation, but is not ordinarily signi?
Occasional exceptions, in which a large difference is observed, can occur under conditions of borderline passivity of metals or alloys that depend on a asstm A method of electrolytic cleaning is described in Practice G 1. It is impractical to propose an inflexible standard laboratory corrosion testing procedure for general use, except for material qualification tests where standardization is required.
It is imperative to note that this usually occurs with no signi? Corrosion testing by its very wstm precludes complete standardization. If cleaning deposits for example, scouring powder remain or lack of asrm dryness is suspected, then recleaning and drying is performed until a constant mass is attained.
This standard is subject to revision at any time by the responsible technical committee and must be reviewed every? These ratios can be achieved through the use of square or circular specimens of minimum thickness. A distinction should be made between those v31 underneath the supporting devices concentration cells and those on the surfaces that were freely exposed to the test solution see Guide G
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