An accelerated corrosion test standard developed by Volvo to evaluate automotive components and coatings.

Introduction

Volvo STD 423-0014 is a test method constructed to evaluate the corrosion resistance of metals, especially in environments with a high concentration of chloride ions, primarily from a marine influence or from winter de-icing chemicals.

The test is incredibly effective in simulating the effects of corrosion in an accelerated and controlled way.

This accelerated test applies to: metals and their alloys, metallic coatings, chemical conversion coatings and organic coatings, and is undertaken on test panels or on suitable test objects and components.

Test Conditions

The test method is composed of approximately 1% NaCL salt mist applications combined with a drying and controlled temperature and humidity phases, the length of the test process is variable.

The recommended specification for the equipment required to undertake this test includes the use of oscillating spray nozzles located high up in the test chamber. These spray salt water solution down on to test samples located beneath, in a precise spray pattern, to ensure a uniform distribution.

Method

The 7 day main test cycle is composed of two twelve hour sub-cycles, one with cycling controlled humidity, the other with salt spray application.

Sub-cycle 1

• Four hours of constant conditions of 35°C at 95% RH
• Temperature increase from 35°C to 45°C with a simultaneous reduction in the relative humidity from 95% RH to 50% over a period of two hours
• Four hours of constant conditions of 45°C at 50% RH
• Temperature decrease from 45°C to 35°C with a simultaneous increase in the relative humidity from 50% RH to 95% over a period of two hours

On Mondays & Fridays, sub-cycle 1 is replaced once by sub-cycle 2

Sub-cycle 2

• 15 minutes spraying with salt solution
• One hour forty five minutes of constant conditions of 35°C at 95%-99% RH to ensure the test subjects remain wet
• The above two stages repeated twice over a 6 hour period
• Drying of the test subjects at a relative humidity set point of 50% RH coinciding with a temperature increase from 35°C to 45°C over two hours.  The required humidity shall be achieved during this period ensuring the test chamber interior and samples are visibly dry
• Two hours of constant conditions of 45°C at 50% RH
• Temperature decrease from 45°C to 35°C with a simultaneous increase in the humidity from 50% RH to 95% over a period of two hours

The test duration will need to be determined by the testing department, however in general a six week test should be enough to rank any bare metal or one protected with a thin conversion coating.

Typical Application

This corrosion test is utilised widely by Scania and by their suppliers as a quality audit of components.

If you would like further information please call our experienced team on 01827 318040 or email sales@ascott-analytical.com

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