ASTM G_Laboratory Immersion Corrosion Testing of Metals. August 18, | Author: Description. Designation: G 31 – 72 (Reapproved ). Buy ASTM G() Standard Practice for Laboratory Immersion Corrosion Testing of Metals from SAI Global. Offering ASTM G31 corrosion testing + modified tests to fit your needs and budget . Rapid, high-quality service by experts.
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Thank you for interesting in our services. For example, a small coupon is not as prone to exhibit pitting as a large one and it is possible to miss the phenomenon altogether in the corrosion testing g13-72 certain alloys, such as the AISI Type series stainless steels in chloride contaminated environments.
G31-7 practice, rather than a standardized procedure, is presented as a guide so that some of the pitfalls of such testing may be avoided. Masking may also be used to g31-27 the desired area ratios but may cause crevice corrosion problems. For relatively soft metals such as aluminum, magnesium, and copperscrubbing with abrasive powder is not always needed and can mar the surface of the specimen. The density in the constant K cancels out the density in the corrosion rate equation.
A number in parentheses indicates the year of last reapproval. One purpose for this guide is to promote better correlation of asstm in the future and the reduction of conflicting reports through a more detailed recording of meaningful factors and conditions.
The values given in parentheses are for information only.
ASTM G31-72_Laboratory Immersion Corrosion Testing of Metals
However, the calculations must not be based on mass loss except in qualification tests such as Practices Awhich is usually small but on microsections which show depth of attack. ASTM International takes no position respecting the validity of any patent y31-72 asserted in connection with any item mentioned in this standard. 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.
It is imperative to note that this usually occurs with no significant loss in mass of the test coupon, although certain refractory metals are an exception to these observations. This guide aatm emphasizes the importance of recording all pertinent data and provides a checklist for reporting test data. For proper interpretation of the results obtained, the specific influence of certain variables must be considered.
A distinction should be made between those occurring underneath the supporting devices concentration cells and those on the surfaces that were freely exposed to the test solution see Guide G Close attention and a more sophisticated evaluation than a simple mass loss measurement are required to detect this phenomenon. If clad alloy specimens are to be used, special attention must be ast, to ensure that excessive metal is not removed. Extraneous effects can be encountered if the air stream impinges on the specimens.
Alternatively, the coupon may be rotated through the environment, although it is then difficult to evaluate the velocity quantitatively because of the stirring effects incurred. Therefore, at least duplicate specimens should normally be exposed in each test.
With a thickness of approximately 3 mm 0. Using the above units for T, A, W, and D, the corrosion rate can be calculated in a variety of units with the following appropriate value of K: Oxygen saturation is a function of the partial pressure of oxygen in the gas.
The choice of a specific treatment must be considered on the basis of the alloy to be tested and the reasons for testing.
In special cases for example, for aluminum and certain copper alloysa minimum of 24 h storage in a desiccator is recommended. This statement must be qualified by stating that corrosion should not proceed to the point where the original specimen size or the exposed area is drastically reduced or where the metal is perforated.
This cannot be evaluated by mass loss alone. If cleaning deposits for example, scouring powder remain or lack of complete dryness is suspected, then recleaning and drying is performed until a constant mass is attained. A commercial surface may sometimes yield the most significant results. Methods for chemical cleaning after testing of specific metals and g3172 are described in Practice G 1. This practice also emphasizes the importance of recording all pertinent data and provides a checklist for reporting test data.
Preferably, the use of a reflux condenser ordinarily precludes the atsm of adding to the original kettle charge. If clad alloys are exposed, special procedures will be required to ensure that only the cladding is exposed, unless the purpose is to test the asym of the cladding to protect cut edges in asmt test solution.
Proper ultrasonic procedures are an acceptable alternate. Separate and special techniques are employed for the specific evaluation of the susceptibility of metals and alloys to stress corrosion cracking see Ref.
We need your help to maintenance this website. With borderline conditions, a ast test may be needed to permit breakdown of the passive film and subsequent more rapid attack. Where required, the exhausted constituents should be added or a fresh solution provided during g3-172 course of the test. These factors include apparatus, sampling, test specimen, test conditions test solution composition, temperature, gas sparging, fluid motion, solution volume, method of supporting test specimens, duration of testmethods of cleaning test specimens, interpretation of results, and calculation of corrosion rates.
The actual time of contact g1-72 the metal with the solution must also be taken into account. This standard does not purport to address all of the safety concerns, if any, associated with its use. These factors include specimen preparation, apparatus, test conditions, methods of cleaning specimens, evaluation of results, and calculation and reporting of corrosion rates.
Other procedures aztm require the removal of solid corrosion products between exposure periods will not measure accurately the normal changes of corrosion with time.
ASTM G_Laboratory Immersion Corrosion Testing of Metals – Free Download PDF
A typical resin flask setup for this type test is shown in Fig. In practice, only alloys of the same general type should be exposed in the testing apparatus.
Please fill this form, we will try to respond as soon as possible. If agitation is required, the apparatus can be modified to accept a suitable stirring mechanism, such as a magnetic stirrer. 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. Configuration of top to flask is such that more sophisticated apparatus can be added as required by the specific test being conducted.
Originally approved in If this is a factor to be considered in a specific test, the solution should be completely aerated or deaerated in accordance with 8.
The corrosion rate can be calculated from the concentration of the matrix metal found in the solution and it can be compared to that determined from the mass loss of the specimens. Last previous edition approved in as G 31 — 72 It is impractical to propose an inflexible standard laboratory corrosion testing procedure for general use, except for material qualification tests where standardization is required.
This practice also emphasizes the importance of recording all pertinent data and provides a checklist for reporting test data.