ASTM G82-98(2014)
Standard Guide for Development and Use of a Galvanic Series for Predicting Galvanic Corrosion Performance

Standard No.

ASTM G82-98(2014)

Release Date

1998

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM G82-98(2021)e1

Latest

ASTM G82-98(2021)e1

Scope

4.1 When two dissimilar metals in electrical contact are exposed to a common electrolyte, one of the metals can undergo increased corrosion while the other can show decreased corrosion. This type of accelerated corrosion is referred to as galvanic corrosion. Because galvanic corrosion can occur at a high rate, it is important that a means be available to alert the user of products or equipment that involve the use of dissimilar metal combinations in an electrolyte of the possible effects of galvanic corrosion.

4.2 One method that is used to predict the effects of galvanic corrosion is to develop a galvanic series by arranging a list of the materials of interest in order of observed corrosion potentials in the environment and conditions of interest. The metal that will suffer increased corrosion in a galvanic couple in that environment can then be predicted from the relative position of the two metals in the series.

4.3 Types of Galvanic Series:

4.3.1 One type of Galvanic Series lists the metals of interest in order of their corrosion potentials, starting with the most active (electronegative) and proceeding in order to the most noble (electropositive). The potentials themselves (versus an appropriate reference half-cell) are listed so that the potential difference between metals in the series can be determined. This type of Galvanic Series has been put in graphical form as a series of bars displaying the range of potentials exhibited by the metal listed opposite each bar. Such a series is illustrated in Fig. 1.

Note 1—Dark boxes indicate active behavior of active-passive alloys.

FIG. 1 Galvanic Series of Various Metals in Flowing Seawater at 2.4 to 4.0 m/s for 5 to 15 Days at 5 to 30°C (Redrawn from Original) (see Footnote 5)

4.3.2 The second type of galvanic series is similar to the first in that it lists the metals of interest in order of their corrosion potentials. The actual potentials themselves are not specified, however. Thus, only the relative position of materials in the series is known and not the magnitude of their potential difference. Such a series is shown in Fig. 2.

ACTIVE END	Magnesium
8199;8199;8199;(−)	Magnesium Alloys
8199;8199;8199;8201;↑	Zinc
8199;8199;8199;8201;