Conventions applicable to electrochemical measurements in corrosion testing

A detailed and well-referenced account of electrochemical methods of testing has been written by Dean, France and Ketcham in a section of the book by Ailor. ASTM G5 1987 outlines standard methods for making potentiostatic and potentiodynamic anodic polarisation measurements and ASTM G3 1974 (R1981) gives conventions applicable to electrochemical measurements in corrosion testing. 

Test method for sandwich corrosion test Recommended practice for preparing, cleaning, and evaluating corrosion test specimens Practice for aqueous corrosion testing of samples of zirconium and zirconium alloys Test method for corrosion testing of products of zirconium, hafnium and their alloys in water at 633 K or in steam at 673 K [metric] Recommended practice for conventions applicable to electrochemical measurements in corrosion testing... 

ASTM G 3-89, Standard Practice for Conventions Applicable to Electrochemical Measurements in Corrosion Testing, American Society for Testing and Materials, Philadelphia, PA, USA, 1989, pp 56-64. 

ASTM G3-74 (1981) Standard Practice for Conventions Applicable to Electrochemical Measurements in Corrosion Testing. 

G 1 Preparing, Cleaning, and Evaluating Corrosion Test Specimens G 3 Conventions Applicable to Electrochemical Measurements in Corrosion Testing G 4 Conducting Corrosion Coupon Tests in Plant Equipment... 

The main variables that are measured in an electrochemical test are the voltage and the current. The goal is to translate this information into a corrosion rate or some other information that describes the corrosion process. ASTM G 3, Practice for Conventions Applicable to Electrochemical Measurements in Corrosion Testing, provides guidelines for conventions for reporting a myriad of electrochemical data for the more common tests. 

Electrochemical tests provide a means to understand the corrosion process, simulate service conditions, or accelerate evaluation of a material [27]. ASTM G 3, Practice for Conventions Applicable to Electrochemical Measurements in Corrosion Testing ASTM G 5, Standard Reference Test Method for Making Potentiostatic and Potentiodynamic Polarization Measurements and ASTM G 61, Standard Test Method for Conducting Cyclic Potentiodynamic Polarization Measurements for Localized Corrosion Susceptibility of Iron-, Nickel-, or Cobalt-Based Alloys provide background in some of these techniques. 

FIG. 10—Typical anodic polarization plot for Type 430 stainless steel in 1.0 N sulfuric acid (from ASTM G 3, Practice for Conventions Applicable to Electrochemical Measurements In Corrosion Testing). 

In ASTM G 3, Standard Practice for Conventions Applicable to Electrochemical Measurements in Corrosion Testing, there are several examples of polarization curves. Figure 7.15 illustrates the ideal polarization behavior one could obtain, for example, using the linear polarization method briefly described below. Figures 7.16 and 7.17 show hypothetical curves for, respectively, active and active-passive behavior, while Fig. 7.18 was plotted from actual polarization data obtained with a S43000 steel specimen immersed in a 0.05 M H2SO4 solution. 

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