Methods & requirements

Ford L-467 Global Laboratory Accelerated Cyclic Corrosion Test

Corrosion testing determines the resistance of materials to corrosion under specific
environmental conditions, like temperature and humidity. Other accelerating factors can be presence of chemicals and the pH-level of the salt fog and pluviometry.

There are mainly two different types of corrosion test standards, field performance and accelerated corrosion tests. Cotec Labs is focused on different types of standardized corrosion tests.

What is important when choosing a test method is to make sure the controlled environment matches the natural outside environment in terms of behaviour of the protective coating when it degrades. Since the methods used in a laboratory environment are accelerated, studies must underpin the extrapolation of test duration.

Control Art Chambers used for Ford L-467 Global Laboratory Accelerated Cyclic Corrosion Test

Ford TM 00.00-L-467 (Ford L-467 or Ford Cyclic)

The test standard Ford L-467 describes a corrosion test method which is an abbreviation of Ford TM 00.00-L-467 and is a cyclic corrosion test method used for testing the corrosion resistance on vehicle parts. The standard Ford L-467 defines a laboratory accelerated atmospheric corrosion test method to be used in assessing corrosion resistance of metals influenced by chloride ions from salt spray solution. This unique cyclic exposure test ads the salt solution through an oscillating spray bar. The test is performed by simulating atmospheric corrosion conditions in a controlled way and it serves as a general-purpose atmospheric corrosion test and applies to a variety of materials, coatings, and interactions of materials, both in the form of test pieces or designed components. The unique cyclic exposure testing method can be useful as a design verification method, when:

Developing and qualifying new corrosion resistant products.
Developing new pre-treatments and finishing processes.
Selecting materials.
Performing quality control of the finished product.
Following Ford Engineering Material Specification, for example WSS-M2P177-
C1/C2/C3, WSS-M21P42-A3 or Worldwide Fastener Standard Ford WX 100.

Procedure and assessment

Samples to be tested for corrosion resistance according to Ford L-467 are tested in controlled climate chambers during a defined exposure time. The exposure time in the test chamber is described by requirement standards and requirement level and depends amongst other on the surface treatment of the test samples.

The accelerated corrosion test is finished when the specified exposure time for the test samples is reached. Upon finishing the corrosion testing the samples are evaluated for corrosion resistance. Several assessments are applicable to evaluate corrosion resistance for example by evaluation general corrosion, propagation from scribe and spontaneous propagation at edges.

Test cycle, sub-cycle 1 and sub-cycle 2

During a cyclic corrosion resistance test according to Ford TM 00.00-L-467 the atmospheric corrosion conditions are accelerated using a cyclic corrosion test method in a controlled chamber.

The test cycles consist of controlled humidity and temperature cycling with application of salt solution by rain phase containing sodium chloride. One test cycle corresponds to one week of testing. The one-week test cycle is composed of two twelve-hour sub-cycles. Sub-cycle 1 consists of controlled and intermittent exposure to varied temperature and humidity, combined with salt application by salt spray exposure that consist of 0.5% NaCl solution. Sub-cycle 2 contains of constant temperature and humidity.

The variation in temperature exposure is 25-50 degrees C and the relative humidity (humidity % RH) exposure reaches from 70 to 95. The complete one-week test cycle consists of 5 repetitions of sub-cycle 1 followed by 2 repetitions of sub-cycle 2.

Corrosion resistance requirements

Corrosion resistance requirements for samples tested by Ford TM 00.00-L-467 are specified by requirement standards. The requirements depend on the substrate and coating of the samples and the environment the samples are exposed to during position in the vehicle.

Example of requirement standards, levels of requirements and changes in requirements where accelerated corrosion testing by test method Ford L-467 is required are:

WSS-M2P177-C1/C2/C3
WSS-M21P42-A3
FLTM BI 024-01
Worldwide Fastener Standard and its S434-S450 series
Ford WX 100 S434
Ford WX 100 S307, S434, S437M/U/L, S439, S440, S442. Revised requirement for
S450 U/B/L
Ford WX 100 S451 replaced salt spray requirements with L-467