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Significance and Use

Electrochemical corrosion rate measurements often provide results in terms of electrical current. Although the conversion of these current values into mass loss rates or penetration rates is based on Faraday's Law, the calculations can be complicated for alloys and metals with elements having multiple valence values. This practice is intended to provide guidance in calculating mass loss and penetration rates for such alloys. Some typical values of equivalent weights for a variety of metals and alloys are provided.

Electrochemical corrosion rate measurements may provide results in terms of electrical resistance. The conversion of these results to either mass loss or penetration rates requires additional electrochemical information. Some approaches for estimating this information are given.

Use of this practice will aid in producing more consistent corrosion rate data from electrochemical results. This will make results from different studies more comparable and minimize calculation errors that may occur in transforming electrochemical results to corrosion rate values.

1. Scope

1.1 This practice covers the providing of guidance in converting the results of electrochemical measurements to rates of uniform corrosion. Calculation methods for converting corrosion current density values to either mass loss rates or average penetration rates are given for most engineering alloys. In addition, some guidelines for converting polarization resistance values to corrosion rates are provided.

1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

D2776 Methods of Test for Corrosivity of Water in the Absence of Heat Transfer (Electrical Methods)

G1 Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens

G5 Reference Test Method for Making Potentiostatic and Potentiodynamic Anodic Polarization Measurements

G59 Test Method for Conducting Potentiodynamic Polarization Resistance Measurements

Keywords

corrosion current; corrosion rate; electrochemical; equivalent weight; polarization resistance; Tafel slopes; Zinc; Zinc alloys; Zirconium (Zr); Alloy equivalent weight; Alloys; Aluminum alloys--corrosion testing; Austenitic steel; Carbon steel; Copper alloy; Corrosion--metals/alloys; Corrosion current density; Current measurement; Density--corrosion current; Electrochemical measurements/testing; Equivalent weight; Faraday's Law; Lead metals/alloys; Magnesium alloys; Mass loss--corrosion; Molybdenum; Nickel alloy pipe; Nickel alloy tube; Penetration; Polarization resistance; Potentiodynamic anodic polarization measurements; Silver; Stainless steel (corrosion testing); Tafel slopes; Tantalum (Ta)/tantalum alloys; Tin metals/alloys; Valence; Weight ;

ICS Code

ICS Number Code 77.060 (Corrosion of metals)

DOI: 10.1520/G0102-89R10

ASTM International is a member of CrossRef.

ASTM G102