Like other corrosion tests GMW is performed to evaluate accelerated corrosion effects on assemblies and different components. A combination of cyclic conditions provides the right environment for this type of accelerated corrosion. It takes 24 hours to complete one full cycle under these conditions which include three 8-hour stages: an ambient stage which has frequent sprays of solution, humid stage which allows for a higher humidity followed by a dry stage. There are two choices when running the cycle on the weekends.
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Like other corrosion tests GMW is performed to evaluate accelerated corrosion effects on assemblies and different components. A combination of cyclic conditions provides the right environment for this type of accelerated corrosion. It takes 24 hours to complete one full cycle under these conditions which include three 8-hour stages: an ambient stage which has frequent sprays of solution, humid stage which allows for a higher humidity followed by a dry stage.
There are two choices when running the cycle on the weekends. Option one is to continue with the normal three stages that are run during the week days and option 2 is an ambient stage for the full 48 hours.
Excluding weekends calls for a longer test duration as the accelerated corrosion process is not in effect. A big part of running a GMW test is the mass loss data collection. Mass loss coupons are special steel chips that have been tested thoroughly to measure the corrosivity of the test.
Based on the variation of test chosen from the variety of test selections a specific mass loss chart is to be followed. The number of salt sprays can vary for each vehicle area as certain areas are more exposed to environmental corrosion than others.
Based on the number of sprays per cycle along with a choice of the five exposures A — E a mass loss value is obtained. This mass loss value is taken from measuring the weight of the sample prior to exposure from the weight of the samples after it has been exposed and rid of all corrosion until bare metal is present.
Corrosion Testing Standards
An accelerated laboratory corrosion test to evaluate automotive coatings and components. Introduction In the American Iron and Steel Institute, in conjunction with a Committee of the SAE, conducted a study of existing cyclic corrosion tests in order to establish the best methods of predicting the performance of materials used in automotive applications. Twenty established corrosion test procedures were included within the study. The process itself comprised of undertaking tests on 10 different materials with each procedure, the results were compared to results gathered through real World exposure from 10 locations around the globe, undertaking the tests with identical materials. The procedures were judged on: Their ability to replicate the rank order of coatings performance in the real World. Method Specimens being tested are exposed to a multi-stage changing environment that is composed of three distinctive cycles, these stages can be varied depending on the nature of the specimen undertaking the test, for further information please refer to the full GMW standard. During this period salt solution is sprayed directly on to the test samples 4 times, for long enough to thoroughly wet them.
GMW Cyclic Corrosion Laboratory Test durability , development testing, and quality control testing, for all global environmental regions refer to GMW for specific Method and applicable region. The basic exposures for cosmetic corrosion are found below in exposures A through C. 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. Note: In the event of conflict between the English and domestic language, the English language shall take precedence. This procedure describes an accelerated laboratory corrosion test method to evaluate assemblies and components.