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GMW14872

3rd Edition, March 2013

Complete Document

Cyclic Corrosion Laboratory Test

Includes all amendments and changes through Change/Amendment , March 2013


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ENGLISH HISTORICAL VERSION
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Product Details:

  • Revision: 3rd Edition, March 2013
  • Published Date: March 2013
  • Status: Historical
  • Document Language: English
  • Published By: General Motors Worldwide (GMW)
  • Page Count: 27
  • ANSI Approved: No
  • DoD Adopted: No

Description / Abstract:

Note: Nothing in this standard supercedes applicable laws and regulations.

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 (pages 25 through 27) of this document 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 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 Table A1 for Method 1/2 and Table A2 for Method 3. 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 Figure A1) used for validation testing (cosmetic and/or functional/general durability), development testing, and quality control testing, for all global environmental regions.

The basic exposures for cosmetic corrosion are found below in exposures 0, A, B, and C. Exposures D and E are used for functional assessment (refer to Table A1 and Table A2). 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 0: All Areas (0 Year/Initial Delivery (ID)).

•  Exposure A: Underbody Components.

•  Exposure B: Underhood Components.

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

•  Exposure D/E: All Components (Functional).

Note: For Exposure 0 (0 Year/ID) evaluate parts at two (2) cycles of the defined exposure linked to the associated vehicle area and mounting location as defined in Table A1 for Method 1/2 and Table A2 for Method 3.

Note: Reference the Deviations Section (pages 25 through 27) for optional modifications.