The “GMW 14872 Cyclic Corrosion Laboratory Test” standard, published by General Motors (GM), describes an accelerated laboratory corrosion testing method for evaluating assemblies and components. The test procedure provides a combination of cyclic conditions (salt solution, varying temperatures, humidity, and ambient light) to accelerate metallic corrosion. The procedure is effective for evaluating various corrosion mechanisms, including general, galvanic, crevice, and similar. Test exposure/conditions can be individually tailored to achieve any desired level of corrosion exposure. Furthermore, synergistic effects arising from temperature, mechanical and electrical cycling, as well as other stresses, can also be understood through this test.
The test method consists of applying approximately 1% complex salt mist along with high temperature, high humidity, and high-temperature drying. One test cycle is equivalent to 24 hours.
A cycle consists of the daily events or test inputs shown in the diagram. Completing a cycle normally takes one day. The test duration is determined according to a targeted coupon mass loss. The target range for the number of cycles required to meet the required mass loss is shown in the table given in the standard. Coupon mass loss values are used by the test to verify that the correct amount of corrosion occurs. In addition to meeting the mass loss requirements, the test must be performed in such a way as to ensure that the number of cycles required to meet the coupon mass loss requirements remains within the specified range.
This procedure is a cyclic corrosion test used for verification testing, development testing, and quality control testing for all global environmental zones.
Basic exposures for cosmetic corrosion can be found in exposures A through C. Exposure D is used for functional evaluation. During testing, all corrosion mechanisms are accelerated at different rates. Completion of the test may not guarantee that a component meets the functional requirement. A comprehensive failure mode analysis should be performed to ensure that all failure modes are considered and the service life is met.
In the fast-paced automotive manufacturing industry, ensuring the longevity and reliability of vehicle components in challenging environmental conditions is of paramount importance. One of the most critical challenges faced by manufacturers is corrosion, which can compromise safety, aesthetics, and performance. The GMW 14872 standard accelerates testing by simulating real-world corrosive environments, allowing engineers to predict and prevent failures before vehicles hit the road. This standard is widely used not only by GM but also by defense industry contractors and other automotive suppliers, and has become a cornerstone of quality assurance in the industry.
The GMW 14872 standard is an advanced test protocol designed to evaluate the corrosion resistance of automotive materials, components, and parts. Unlike traditional salt spray tests, which expose samples to continuous salt water vapor, this standard uses a cyclical approach, alternating between wet, dry, and ambient phases to more accurately simulate globally encountered outdoor exposure conditions. This encompasses everything from coastal humidity to ice-free roads in winter.
This standard is based on the GM 9540P standard and adds specific relative humidity controls in ambient and dry phases to better represent different climates. It provides guidelines for testing parts in various vehicle locations such as under the hood (high-heat areas), the exterior (weather-exposed), secondary surfaces (less critical but still vulnerable), and even interior components.
The GMW 14872 standard uses the GMW 14700 standard as a reference for stone impact resistance and the GMW 15282 standard as a reference for corrosion wear assessment.
Besides being an unsightly problem, corrosion can lead to structural weaknesses, electrical failures, and costly recalls. The GMW 14872 standard helps manufacturers in these areas:
The GMW 14872 standard test cycle is a complex sequence of environmental stresses run in dedicated chambers, typically controlled by programmable logic controllers, for accuracy and repeatability. The steps of a standard cycle are as follows:
A full cycle takes approximately 6,5 hours, and total exposure times vary depending on the component type: typically 10–20 cycles (approximately 2–4 weeks) for exterior parts. The solution used is a precise mixture of sodium chloride, calcium chloride, and sodium bicarbonate to mimic road salts and atmospheric pollutants.
For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services to businesses in accordance with the "GMW 14872 Cyclic Corrosion Laboratory Test" standard.
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