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.
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The degree of lateral spreading of pits may ast be noted. Warning—In many cases the corrosion product on the reactive metals titanium and zirconium is a hard and tightly bonded oxide that de? The mechanical property commonly used for comparison is the tensile strength.
Duplicate strips of low-carbon steel, each 19 by 76 mm 3?
ASTM G Standard Practice for Laboratory Immersion Corrosion Testing of Metals_百度文库
The mass loss during the test period can be used as the principal measure of corrosion. This statement must be quali? In sstm such cases, corrosion rates are established by mass gain rather than mass loss. If you feel that your comments have not received a fair hearing you should g331 your views known to the ASTM Committee on Standards, at the address shown below.
Chemicals are chosen for application to a speci? Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.
In practice, only alloys of the same general type should be exposed in asttm testing apparatus. Therefore, at least duplicate specimens should normally be exposed in each test.
Methods for chemical cleaning after testing of speci? Circular specimens should preferably be cut from sheet and not bar stock, to minimize the exposed end grain.
ASTM NACE / ASTMG31 – 12a Standard Guide for Laboratory Immersion Corrosion Testing of Metals
Generally, if cracking is observed on the coupon, it can be taken as positive indication of susceptibility, whereas failure to asgm this phenomenon simply means that it did not occur under the duration and speci?
If there are any pits, the average and maximum depths of pits are determined with a pit gage or a calibrated microscope which can be focused? It may be desirable to test a surface representative of the material and metallurgical conditions used in practice.
These ratios can be achieved through the use of square or circular specimens of minimum thickness. A method of electrolytic cleaning is described in Practice G 1. Historical Version s – view previous versions of standard. 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 of certain alloys, such as the AISI Type series stainless steels in chloride contaminated environments.
These factors include oxygen concentration, temperature, rate of? With a thickness of approximately 3 mm 0. Corrosion testing by its very nature precludes complete standardization.
One purpose for this guide is to promote better correlation of results in the future and the reduction of conflicting reports through a more detailed recording of meaningful factors and conditions. This standard, rather than a standardized procedure, is presented as a guide so that some of the pitfalls of such testing may be avoided.
With borderline conditions, a prolonged test may be needed to permit breakdown of the passive? The others are used principally as a supplement to remove heavily encrusted corrosion products before scrubbing. Too much surface preparation may remove segregated elements, surface contamination, and so forth, and therefore not be representative.
These factors include specimen preparation, apparatus, test conditions, methods of cleaning specimens, evaluation of results, and calculation and reporting of corrosion rates. Careful observation is needed to ensure that pitting does not occur during cleaning. The actual time of contact of the metal with the solution must also be taken into account. Cupric ions may also exhibit a passivating effect upon stainless steel coupons exposed at the same time.
In many such cases, corrosion rates are established by mass gain rather than mass loss. Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm. The amount of possible contamination can be estimated from the loss in mass of the specimen, with proper application of the expected relationships among 1 the area of corroding surface, 2 the mass of the chemical product handled, and 3 the duration of contact of a unit of mass of the chemical product with the corroding surface.
The values given in parentheses are for information only. It should be observed, however, that galvanic corrosion can be greatly affected by the area ratios of the respective metals, the distance between the metals and the resistivity of the electrolyte. For example, lead exposed to sulfuric acid corrodes at an extremely high rate at?
Molarity and normality are also helpful in de? 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 ability of the cladding to protect cut edges in the test solution.
This standard is subject to revision at any time by the responsible technical committee and must be reviewed every? 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. Proper ultrasonic procedures are an acceptable alternate. There are a number of other special types of phenomena of which one must be aware in the design and interpretation of corrosion tests.