Testing by ASTM G48 for Pitting and Crevice Corrosion

When using stainless and duplex steels, ASTM G48 is widely used to ensure the quality of the material and resistance to pitting and crevice corrosion. ASTM G 48 is a relatively severe test, but lack of definition in the standard can lead to variation of data. We follow a standard practice we have developed to minimize these variations and provide consistent data. However, the G48 test is meant for ranking or qualification, and not as designed for determining a corrosion rate over time.

There are 6 Methods: A and B are for qualification of alloys to pitting and crevice corrosion at specific temperatures, C and D are for determining the critical pitting and crevice corrosion temperatures of chromium and nickel alloys, and E and F are for stainless alloys. And when etched correctly, it’s just beautiful:

Duplex stainless steel microstructure

ASTM G48 Methods A-F: Which test do I need?

Which one do you need? The answer is: it depends. There are several factors that can influence the selection of methods; we can help you with this part of the process as well. The available pitting and crevice testing methods include:

 

Method AFerric chloride pitting test.

Method BFerric chloride crevice test.

Method CCritical pitting temperature test for nickel-base and chromium-bearing alloys.

Method DCritical crevice temperature test for nickel-base and chromium-bearing alloys.

Method ECritical pitting temperature test for stainless steels.

Method FCritical crevice temperature test for stainless steels.

The ASTM G 48 Standard:

The ASTM G 48 Standard is entitled “Standard Test Methods for Pitting and Crevice Corrosion Resistance of Stainless Steels and Related Alloys by Use of Ferric Chloride Solution” and is widely used to analyze stainless, duplex, and nickel-based alloys. Our lab offers all 6 methods of this test as well as ASTM G150, the electrochemical method for similar analysis. In many ways, G150 is ideal for use instead of methods C-F as it is a more rapid method that can be performed within 1-2 days instead of weeks. Not sure what you need? Contact our corrosion experts today!

ASTM G48 Testing by G2MT Labs - 100X magnification