Scope:

ASTM B117 test method is used to create and maintain the salt spray (fog) test environment that impacts many industries with regard to quality control. The test is used to compare the corrosive resistance of different metals, determine suitable materials for a specific environment, and determine corrosion creep and coating adhesion. This test provides useful information for developing coatings and new materials. The industries such as aircraft, transport, paint, infrastructure, and automotive benefit from these tests. 

Test procedure:

For the ASTM B117 test, a metallic sample is placed in a controlled chamber. The sample is sprayed at different angles and locations with a salt solution. The salt concentration ranges from 3.5-20 % and usually is higher than that in the atmosphere. The chambers required for handling large samples come in different sizes and designs, ranging from small sizes to walk-in rooms. 
To create hot and humid air for ASTM B117 testing, a humidifying tower with hot and deionized water is provided, which is accomplished by bubbling compressed air via the tower. Then, the salt solution is mixed with hot and humid air at the nozzle, and a corrosive fog is formed. The relative humidity produced by this fog is 100 %. If lower humidity conditions are desired, the air is blown into the chamber’s exposure zone.

Sample size:

The number and type of test sample required for ASTM B117 are defined upon mutual agreement between the seller and the purchaser.

Data:

The following data is required for ASTM B117 testing:
Concentration or specific gravity
The pH of the collected solution

Conclusion:

ASTM B117 test method determines the role of salt in enhancing the corrosive resistance of materials in response to salt. The quality and durability check is performed, testing the reliability of various materials for commercial use.