ASTM G46 Examination and Evaluation of Pitting Corrosion

Scope:

The ASTM G46 can evaluate the level of pitting in a service application where the remaining life of a metal structure must be predicted. This test is used for a variety of purposes, including evaluating alloy performance, establishing if an alloy is resistant to the environment, and analyzing how environmental variables, such as corrosion inhibitors, affect or prevent pitting.

Procedure:

In ASTM G46, before any cleaning or destructive inspection, a visual inspection of the corroded metal surface was normally performed in its as-received state. By using a depth gauge or micrometre extent of the pitting was determined. The evaluation of the pitting was done with the help of Automated Profilometers.

Video 01: Crevice and pitting corrosion

Specimen size:

For ASTM G46, the pit depth measurements are taken in the range of 0.04 mm to 0.34 mm.

Calculations:

Pitting probability can be calculated by using the following equation:

P = Np/N × 100

Np = Specimens that pit

N= total number of specimens

Conclusion:

By using this ASTM G46 method, the pitting corrosion of a wide variety of metals is determined.