ASTM G5-13

3.1 The availability of a standard procedure, standard material, and a standard plot should make it easy for an investigator to check his techniques. This should lead to polarization curves in the literature which can be compared with confidence.

3.2 Samples of a standard ferritic Type 430 stainless steel (UNS S43000) used in obtaining standard reference plot are available for those who wish to check their own test procedure and equipment.³

3.3 Standard potentiodynamic polarization plots are shown for a lot of material originally purchased in 1992. This test method is not applicable for standard material purchased before 1992. These reference data are based on the results from different laboratories that followed the standard procedure, using that material in 1.0 N H₂SO₄. The four sigma probability bands for current density values are shown at each potential to indicate the acceptable range of values.

3.4 This test method may not be appropriate for polarization testing of all materials or in all environments.

3.5 This test method is intended for use in evaluating the accuracy of a given electrochemical test apparatus, not for use in evaluating materials performance. Therefore, the use of the plots in Fig. 1 is not recommended to evaluate alloys other than Type 430, or lots of Type 430 other than those available through Metal Samples. The use of the data in this test method in this manner is beyond the scope and intended use of this test method. Users of this test method are advised to evaluate test results relative to the scatter bands corresponding to the particular lot of Type 430 stainless steel that was tested.

CURRENT DENSITY (μA/cm²)

FIG. 1 Typical Standard Potentiodynamic Anodic Polarization Plot