Pitting and crevice corrosion can be challenging to detect and predict, so understanding the risk factors of corrosion and susceptibility of a material can help anticipate issues before they arise. Element offers pitting and corrosion testing for your stainless steels/alloys and metal products used in many industries including Oil & Gas, Aerospace, Infrastructure, Environmental and Industrials. 

If a material exhibits holes or gaps on its surface, pitting or crevice corrosion may be the culprit. Pitting corrosion is characterized by small holes on a material. Crevice corrosion, on the other hand, occurs around the gap where two materials meet. 

Pitting can be one of the most dangerous types of corrosion. It is difficult to anticipate and may also occur very rapidly and only affects a localized area, with the vast majority of the surface remaining unaffected. 

With state-of-the-art facilities and access to a global network of expertise, Element’s materials testing and corrosion labs provide a number of different test methods for testing pitting and crevice corrosion in the USA, Europe, Middle East, Asia, and Africa. 

Pitting corrosion ASTM G48 A, C and E test methods

Element performs pitting corrosion testing in accordance with ASTM G48 A at test temperature, typically up to 60°C. The test involves the exposure of the materials in a 6 wt % ferrite chloride solution for test durations of 72 hours (typically 24 hours). A variation of the ASTM G48-A test used for duplex stainless steels is the ASTM A923 method – C test. 

The temperature which pitting initiates can be determined using a Critical Pitting Temperature (CPT) test method. In ASTM G48 there are two test methods; one for stainless steels method – C, and one for nickel alloys method – E. In the CPT methods specimens are exposed for 72 hour periods to incrementally increasing temperatures until pitting is observed which is recorded as the critical pitting temperature (CPT). 

As an alternative to the G48 methods for the determination of CPT, critical pitting corrosion temperature can be determined using the electrochemical test method described in ASTM150. In this method, the specimen is polarized and the temperature of the solution increased until a rapid rise of the corrosion current is detected which is CPT. 

Crevice corrosion ASTM G48 B, D, and F test methods

Element performs crevice corrosion testing in accordance with ASTM G48 B at the test temperature, typically up to 60°C. The test involves the exposure of the materials in a 6 wt % ferrite chloride solution for test durations of 72 hours (typically 24 hours). 

The temperature at which crevices initiate can be determined using a Critical Crevice Temperature (CCT) test method. In ASTM G48 there are two test methods, one for stainless steels method – D and one for nickel alloys method – F. In the CPT methods, specimens are exposed for 72 hour periods to incrementally increasing temperatures until a crevice is observed which is recorded as CCT. 

Our in-depth knowledge of the industry standards and corrosion testing programs means that we can advise you on the most suitable test method for your materials. Choosing the correct test method is crucial to achieve positive test results first time right and avoid costly delays in your project schedules, saving you time and money as a result. 

Crevice corrosion ASTM G78 test method 

Element offers crevice corrosion testing in accordance with ASTM G78 at the test temperature, typically up to 60°C. The test involves the application of castellated washers (MCAs) to the surface of the specimen, typically with 20 contact points on each washer in a chloride-containing environment (seawater) for a test duration of up to 30 hours (typically 24 hours). At the end of the test period the specimens are examined for evidence of crevice corrosion. 

Evaluation of pitting and crevice corrosion 

Element’s corrosion laboratories use ASTM G46 for evaluation of pitting and crevice corrosion. More detailed evaluation can also be conducted using Electron Scanning Microscopy.  

For more information about how we perform Pitting and Crevice Corrosion Testing, or to request a quote, contact us today. 
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