Scope: 

The ASTM D6138 is a standard test method for the determination of corrosion-preventive properties of lubricating greases under dynamic wet conditions. This test method evaluates the grease’s capacity to resist corrosion in rolling bearings operating in distilled water, sodium chloride solution, or synthetic seawater. It is employed in the development and specification of products.

Test procedure:

For ASTM D6138, new, cleaned, and lubricated bearings are tested when they are partially immersed in water (distilled, synthetic seawater, or sodium chloride solution) under no applied load at a speed of 83 ± 5 rpm in a predetermined sequence of running and stopping for a period of approximately one week. Then, the bearing rings are evaluated and rated according to the degree of corrosion after they have been cleaned. 

Video 01: Corrosion preventive properties of lubricating greases

Specimen size:

Test bearings that have outer rings and balls entirely free of corrosion are used as test specimens for the ASTM D6138 test procedure. 

Data:

The degree of corrosion and the type of water solution used for the test are reported according to  ASTM D6138. The two figures are presented if the two ratings agree within the repeatable precision given; else, two more determinations are made.

Conclusion:

The ASTM D6138 is a standard test method for the determination of corrosion-preventive properties of lubricating greases under dynamic wet conditions.