GMNA GM9540P PDF

This procedure describes an accelerated laboratory corrosion test method to evaluate assemblies and components. The test procedure provides a combination of cyclic conditions (salt solution, various temperatures, humidity, and ambient environment) to accelerate metallic corrosion. The procedure is effective for evaluating a variety of corrosion mechanisms, such as general, galvanic, crevice, etc. The test duration can be individually tailored to achieve any desired level of corrosion exposure.

Also, synergistic effects due to temperature, mechanical and electrical cycling can be comprehended by this test. See Appendix A for typical modifications.

NOTE: Test durations A and B can be used as both QC tests and validation tests depending on the purpose of the test. Test durations C and D or any modified test are to be used for validation and development purposes.

The test method is comprised of 1.25% (0.9% sodium chloride, 0.1% calcium chloride and 0.25% sodium bicarbonate) salt mist applications coupled with high temperature and high humidity and moderately high temperature dry off. It requires a 16 h work day or an automatic cycling test chamber.

IMPORTANT: Engineering drawings and material specifications that reference this test procedure must specify the test duration, (A, B, C or D) or the number of test cycles as indicated in Table 1. (Example, GM9540P, Test Duration B.) In addition, the criteria for making pass/fail determinations must be specified. Test durations A and B can be used for quality control and validation procedures as appropriate. Longer test durations (C and D) and tests involving modifications are to be used for validation purposes only.

NOTE 1: A cycle is made up of the daily events or test inputs prescribed in Table 4. A cycle normally requires 1 day to complete. The test duration is dictated by the number of test cycles.

NOTE 2: A phase is made up of a predetermined number of cycles, 8 cycles constitute 1 phase.

NOTE 3: The coupon mass loss values shown in Table 2 are used to verify that the correct amount of corrosion has been produced by the test.