GMW GMW14872 PDF

Note: Nothing in the standard supersedes applicable laws and regulations unless specific exemption has been obtained.

Note: In the event of conflict between the English and domestic language, the English language shall take precedence.

Purpose.

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 exposure/conditions can be individually tailored to achieve any desired level of corrosion exposure.

Also, synergistic effects due to temperature, mechanical and electrical cycling along with other stresses can be comprehended by this test. See Deviations Section, which after the Appendices, for typical modifications.

Foreword.

The test method is comprised of 1% (approximate) complex salt mist applications coupled with high temperature and high humidity and high temperature dry off. One (1) test cycle is equal to 24 h.

A cycle is made up of the daily events or test inputs illustrated in Appendix A, Figure A1. A cycle normally requires one (1) day to complete. The test exposure is dictated by a targeted coupon mass loss. A target range for the number of cycles necessary to meet the required mass loss is provided in Appendix A, Table A1. The coupon mass loss values are used to verify that the correct amount of corrosion has been produced by the test. In addition to meeting mass loss requirements, the test must be conducted such that the number of cycles required to meet coupon mass loss requirements falls within the specified range.

Applicability.

This is a cyclic corrosion test (refer to Appendix A, Figure A1) used for validation testing (cosmetic and/or functional/general durability), development testing, and quality control testing, for all global environmental regions (refer to GMW8738 for specific Method and applicable region).

The basic exposures for cosmetic corrosion are found below in exposures A through C. Exposure D is used for functional assessment (refer to Appendix A, Table A1). All corrosion mechanisms are accelerated at different rates on test. Completing the test may not ensure that a component passes the functional requirement. A comprehensive failure mode analysis must be conducted to ensure all failure modes are considered and life expectancy is met.

Exposure A: Underbody Components

Exposure B: Underhood Components

Exposure C: Exterior Components/Panels, Secondary Surfaces, and Interior Components

Exposure D: All Components (Functional)

Note: Reference the Deviations section of this document for optional modifications.