ASTM D4048 test method for detection of copper corrosion from lubricating grease
4. Summary of Test Method
4.1 A prepared copper strip is totally immersed in a sample of grease and heated in an oven or liquid bath at a specified temperature for a definite period of time. Commonly used conditions are 100 more or less 1°C (212 more or less 2°F) for 24 h more or less 5 min. At the end of this heating period, the strip is removed, washed, and compared with the Copper Strip Corrosion Standard.
5. Significance and Use
5.1 This test method measures the tendency of lubricating grease to corrode copper under specific static conditions. It may be of some value in predicting possible chemical attack on lubricated parts, such as bearings that contain copper or copper alloys. Such corrosion, for example, can cause premature bearing failures. However, no correlations with actual field service, most of which are under dynamic conditions, have been established. It does not measure either the ability of the lubricant to inhibit copper corrosion caused by factors other than the lubricant itself nor does it measure the stability of the grease in the presence of copper.
