ASTM G48 Standard Test Methods for Pitting and Crevice Corrosion Resistance of Stainless Steels

Get Certified ASTM G48 Pitting and Crevice Corrosion Testing

ASTM G48 is a testing method that evaluates stainless steels under controlled laboratory conditions for localized corrosion resistance. Technicians prepare representative specimens, apply the specified exposure conditions, and use the applicable test method for pitting or crevice corrosion evaluation. Analysts examine the specimens for localized attack and determine the applicable corrosion resistance result. Results can help with material selection, quality control, product development, and corrosion performance evaluation.

• Material Type: Stainless steels and related corrosion-resistant alloys.
• Purpose: Evaluation of resistance to pitting and crevice corrosion.
• Property Measured: Resistance to localized corrosion under specified ferric chloride exposure conditions.
• Method: Controlled exposure of prepared specimens to ferric chloride solution using the applicable ASTM G48 method.
• Result: Corrosion behavior, including mass loss and/or evidence of pitting or crevice attack, as applicable to the selected method.
• Test Limitations: Results depend on alloy composition, specimen surface condition, exposure temperature, exposure time, solution condition, and test configuration.
• Environmental Conditions: Controlled ferric chloride solution, temperature, and exposure conditions.
• Applications: Stainless steel comparison, corrosion-resistant alloy evaluation, material selection, quality control, and research.

What are the uses of ASTM G48 Testing?

ASTM G48 testing assesses the localized corrosion resistance of stainless steels in aggressive chloride environments. The methods offer a controlled environment to compare the pitting and crevice corrosion responses of various materials. Engineers and corrosion specialists use the results to support material selection and assess performance for applications where localized corrosion is a concern. The test helps to:

• Pitting Corrosion Evaluation: Determines the tendency of stainless steel to develop localized pits.
• Crevice Corrosion Evaluation: Assesses susceptibility to corrosion in crevice conditions.
• Material Comparison: Compares localized corrosion resistance among stainless steel grades.
• Material Selection: Supports material selection for chloride-containing environments.
• Quality Control: Provides corrosion-performance information for specified materials.
• Product Development: Supports development and evaluation of corrosion-resistant alloys.
• Research: Provides data for corrosion studies and material-performance investigations.

Which Materials Can Be Tested According to ASTM G48?

Technicians prepare sample pieces with the required surfaces and sizes, then place them in the ferric chloride solution ASTM G48 specifies. The choice of test method and how the sample is set up depends on whether the test’s looking at pitting corrosion, crevice corrosion, or some other type of local corrosion that ASTM G48 covers. The method applies to:

• Evaluation of susceptibility to pitting corrosion: Identifies the potential susceptibility of stainless steel to pitting corrosion. 
• Crevice Corrosion Detection: Tests for crevice corrosion. 
• Material Comparison: Compares the localized corrosion resistance of stainless steel grades. 
• Material Selection: Can select materials used in chloride environments. Quality Control: Gives corrosion performance data for a specified material. 
• Product Development: Assists with product development and evaluation of corrosion-resistant alloys. 
• Field observations and samples: Collects field samples for study, testing, and evaluation.

Why is ASTM G48 Testing Important?

Localized corrosion can cause damage even when the metal surface is relatively clean. ASTM G48 offers controlled accelerated exposure conditions to test the susceptibility of S/S to pitting and crevice corrosion. The results provide information for engineers that helps them understand the differences in localized corrosion resistance between materials. The test can also support material selection for applications involving chloride exposure. By using controlled specimen preparation, exposure conditions, and evaluation procedures, technicians can generate comparable corrosion-performance information.

ASTM G48 Testing Process and Data Collection

The technicians prepare the stainless steel samples and set up the required ferric chloride test. They expose the specimens under controlled temperature and time as per the ASTM G48 method. Techniques are used to clean and inspect the specimens after exposure and to take the necessary measurements. The observed corrosion is assessed, appropriate results are calculated, and the material’s resistance to localized attack is recorded. The corrosion data obtained suggests the susceptibility of the stainless steel to pit or crevice corrosion under the given test conditions.

Common Challenges and Troubleshooting

External factors such as differences in the level of the surface condition of the specimen, strength and concentration of ferric chloride solution, temperature, exposure duration, sample preparation, and cleaning procedures before and after the test may affect the results of ASTM G48. Technical personnel should be consistent with the time, temperature, and file condition of the specimen and solution throughout the experiment. 

• The laboratory reports the initial and final specimen mass in g and records the calculated or evaluated corrosion results according to the applicable procedure.
• The technician records specimen dimensions in mm, surface condition, ferric chloride exposure conditions, test temperature in °C, and exposure time in h.
• The analyst documents observed pitting or crevice corrosion and records the location and characteristics of relevant corrosion damage.
• Analysts record specimen identification, preparation details, solution conditions, post-exposure cleaning, inspection, and other required test information.
• Engineers compare the observed or calculated corrosion results among stainless steel materials to support material selection for applications involving chloride exposure.

Link to ASTM G48