Comparative Analysis of Different Corrosion Test Cycles 2023-28-1325

Corrosion in automotive industry is broadly categorized into cosmetic & perforation corrosion. Cosmetic corrosion comprises of superficial red rust which is deleterious to the overall aesthetic appeal of the vehicle but can be rectified. Perforation corrosion involves complete erosion of the panel, compromising structural integrity of the respective part. Perforation corrosion demands part replacement. In order to tackle this menace, automotive OEMs have formulated varied corrosion strategies in terms of selection of appropriate substrate, part design & surface protection scheme.

Validation of various corrosion strategies become pivotal during the development phase of various parts and assemblies. Traditionally, Salt Spray Test (SST) has been used to determine corrosion life of materials/parts/assemblies. This test however does not simulate real-world conditions. Another test method, Cyclic Corrosion Test (CCT) with dynamic state conditions, wherein the relative corrosion rates, corrosion structure and morphology are more similar to those seen outdoors. However, there exist numerous CCT cycles having varied frequencies and intensities of salt fogging, wetting, ambient & drying cycles. Moreover, OEMs have formulated various-vehicle level Proving Ground tests wherein entire vehicle assembly is subjected to an accelerated corrosive condition.

In the present Indian automotive industry, there does not exist a correlation between the predominantly used corrosion test cycles. In this study we have undertaken exhaustive evaluation of cosmetic corrosion performance in SST & CCT-two different Test Cycles. The cosmetic corrosion performance has been characterized based on observed creep-back analysis, after 1400 hours of testing. A comparative analysis has been undertaken of the cosmetic corrosion performance observed in various test cycles with respect to Proving Ground tests.