VDA 233-102 Cyclic Corrosion Testing of Materials and Components in Automotive Construction

The standard “VDA 233-102 Cyclic corrosion testing of materials and components in automotive construction” published by the German Association of the Automotive Industry (VDA) is a specification developed jointly by the automotive, steel and aluminium industries. Designed to provide a standard for cyclic corrosion testing of new materials and coatings in the automotive industry, this test method is intended to eventually replace the test described in the old standard “VDA 621-415 Testing of corrosion protection of vehicle paint by alternating cyclic testing”.

The function of the standard is to provide an accelerated test process for the evaluation of the corrosion behaviour of components and the corrosion protection provided by coatings. The accelerated testing covers, in particular, delamination/corrosion creep around a defined artificial defect in a coating and surface and edge corrosion on special test plates, clamping specimens or components.

The test is particularly suitable for evaluating corrosion creep around defects in coatings, e.g. flanged areas or gaps and unpainted surfaces.

A lower ageing rate of the adhesive can be expected compared to tests with higher moisture presence. This laboratory-scale cyclic corrosion test is particularly suitable for the evaluation of corrosion creep around defects in coatings, e.g. flanged areas or gaps and unpainted surfaces. This test method is based on real corrosive conditions and offers differentiated results for a wide range of uses in automotive applications.

When performing the test, test samples are placed in a closed chamber and placed at an angle of 65 degrees to 75 degrees to the horizontal with the side to be tested uppermost. The salt spray stage is performed with a 12 percent sodium chloride solution (pH 6,5 to 7,1) and the samples are sprayed at a rate of 2,0 to 4,0 ml/80 cm² per hour.

Test duration is determined on a case-by-case basis based on the time required to draw conclusions about corrosion behavior.

A complete testing cycle takes 7 days and consists of the following steps:

• 3 times, cycle A without 24-hour freezing phase, with 3-hour salt spray phase
• 3 times, 24 hours cycle B without freezing phase, without salt spray phase including evaluation of samples
• 1 time, Cycle C with 24-hour freezing phase, without salt spray phase

The cycles are multi-step cycles consisting of temperatures ranging from minus 15 degrees to plus 50 degrees and humidity values ​​ranging from 50 percent to 95 percent. Typical test duration is six complete test cycles.

According to this standard, tolerances are as follows:

• Temperature tolerance plus/minus 2 degrees
• Relative humidity plus or minus 3 percent
• When temperature ramps are passed during periods of constant relative humidity, deviations of 8 percent to 5 percent relative humidity are acceptable.

This method produces corrosion patterns that are directly comparable to results obtained in the real-world automotive environment, particularly for steel, galvanized steel and aluminum. The described test method initiates corrosion processes and provides reproducible corrosion results that correlate well with results obtained in natural wear tests (e.g. standard “DIN 55665 Paints and varnishes - Natural wear of coatings - Determination of corrosion protection performance”) and in driving. In particular, the corrosion patterns for steel, galvanized steel and aluminum substrates closely reflect real-life events.

This test method is based on real corrosive climate conditions and provides differentiated results for a wide range of uses in automotive applications.

Among the numerous testing, measurement, analysis and evaluation studies carried out for businesses in various sectors, our organization also provides testing services defined in the "VDA 233-102 Cyclic corrosion testing of materials and components in automotive construction" standard with its trained and expert staff and advanced technological equipment.