ASTM G102 PDF
Description. ASTM G Standard Practice for Calculation of Corrosion Rates and Related Information from Electrochemical Measurements. View more. ASTM G()e1. Standard Practice for Calculation of Corrosion Rates and Related Information from Electrochemical Measurements. ASTM-G Standard Practice for Calculation of Corrosion Rates and Related Information from Electrochemical Measurements – corrosion.
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This will cause either the anodic or cathodic b value to appear smaller than the corrosion reaction above. Consider a unit mass of alloy oxidized.
B5 g1102 bc 2.
See Refs for more information. In this case, the concentration of the corroding electrode ions is generally of the same magnitude or higher than other ions participating in the corrosion process in the electrolyte surrounding the electrode. Calculation methods for converting corrosion current density values to either mass loss rates or average penetration rates are given for most engineering alloys.
It is usually assumed that the process of oxidation is uniform and Copyright? In general, Eq 7 and Eq 8 may be used, and the corrosion rate calculated by these two approximations may be used as lower and upper limits of the true rate.
In addition, some rationale must be adopted for assigning values of n to the elements in the alloy because many elements exhibit more than one valence value.
ASTM G Standard Practice – Free Download PDF
Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. The capacitance charging effect will cause the calculated polarization resistance to be in error. A sample calculation is given in Appendix X2 1. This is accomplished by dividing the total current by the geometric area of the electrode exposed to the solution.
Equilibrium diagrams showing regions of stability of various phases as a function of potential and pH may be created from thermodynamic data. The conversion of these results to either mass loss or penetration rates requires additional electrochemical information. In some computerized polarization equipment, this calculation is made automatically after the specimen area is programmed into the computer.
In addition, some guidelines for converting polarization resistance values to corrosion rates are provided. It is best if an independent technique can be used to establish the proper valence for each alloying element.
ASTM G102 Standard Practice
A sample calculation is given in Appendix X6. Normally only elements above 1 mass percent in the alloy are included in the calculation. Calculation methods for converting corrosion current density values to either mass loss rates or average penetration rates are given for most engineering alloys.
Other units may be used in this calculation.
Other redox couples that do not necessarily participate in the corrosion reaction may have similar effects. Another approach is to measure or estimate the electrode potential of the corroding surface.
Current edition approved Feb. This calculation may be expressed as follows: In general, Tafel slopes are given by Historical Version s – view previous versions of standard. Although the conversion of these current values into mass loss rates or penetration rates is based on Asmt Law, the calculations can be complicated for alloys and metals with elements having multiple valence values.
A number in parentheses indicates the g02 of last reapproval. The estimation of a B value for situations involving mixed control requires more information in general and is beyond the scope of this standard.
This is especially true for metals exhibiting passive behavior. Therefore, the gram equivalents of the dissolved components are given by Eq 3.
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. In addition, some guidelines for converting polarization resistance values to corrosion rates are provided. ASTM D standar Icor icor 5 A 1 where: Values of 65 and mV are also commonly used. A superscript epsilon e indicates an editorial change since the last revision or reapproval.
KRT b 5 nF 9 where: Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Q 5 Wi 3 where: