Why postfabrication surface treatment of stainless steel is important

Best practise in stainless steel fabrication includes maintaining or restoring clean metallic surfaces. When discolouration is observed, for instance, on edges, in welds or in the heat affected zone, it should always be removed.

Heat tint in not merely an aesthetic question: the oxides, which are visible as discolorations, do not have the protective and self-repairing properties that the original passive layer has. It should therefore be removed even from non-visible parts of a fabrication. Depending on the application and the surface requirements, this can be done by mechanical or chemical means – or a combination of both.
Ferrous contamination can be another point of concern. When dust from the cutting, grinding or welding of carbon steel deposits on stainless steel, it corrodes quickly and forms unsightly rusty spots. Also temporary contact of unprotected stainless steel surfaces with carbon steel racks or lifting gear can leave iron traces. Where such ferrous contamination has occurred, appropriate surface treatment is strongly recommended.

However, there is wide-spread uncertainly about a number of questions: What is the difference between pickling and passivating? When should mechanical and chemical surface treatment be preferred respectively?

Euro Inox devoted a concise new brochure to the most frequently asked questions about post-fabrication surface treatment and explains the relevant techniques. An annex indicates the compositions of common chemicals and lists standard parameters for their use. A literature list refers to standards and other sources of further information. The eleven-page paper can be downloaded free of charge from http://www.euro-inox.org/pdf/map/PostFabricationSurfaceFinishing_EN.pdf

Suitable surface finishing techniques are available for stainless steel fabrications of any size. Photo: Euro Inox, Brussels (B) / eot, Wedemark (D)

Published 26/03/2015 19:23:30 Last Modified 26/03/2015 19:25:44

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