Datasheets

Stainless Steel - General Information - Is Stainless Steel Really Maintenance Free

Datasheets

Is Stainless Steel Really Maintenance Free

Introduction

Many people believe that stainless steel can’t get rusty and that stainless steel is completely rust-proof.  In fact, although stainless steel is an alloy that contains chromium and other elements offering a certain amount of resistance to corrosion the base material is virtually as active as ordinary carbon steel. 

The noble nature of stainless is due to an ultra-thin passive Chromium Oxide layer on the surface, but in the absence of this layer the material is rapidly corroded.  So good care should be taken of this oxide layer to ensure stainless steel will last a lifetime.  In other words, stainless steel is not at all maintenance-free.  It can, however, be said to be low maintenance. 

A component made from stainless steel can be compared to a healthy apple that keeps for a long time thanks to its peel, which is less than a tenth of a millimeter thick, but no substances are able to escape or enter – until  a worm eats its way through the peel, triggering the rotting process.  The flesh of the apple will also oxidize quickly when the apple is cut in half. 

The ‘skin’ on stainless steel is much thinner than apple peel yet also provides complete enclosure, which is why, normally speaking, no metal ions can escape and no foreign substances can enter.  However, if this skin is exposed to an excessive chemical load, it will break down, leading to corrosion.  The biggest difference from the apple is the ability of stainless steel to repair its oxide layer by itself.  This is particularly applicable when the layer is damaged mechanically and the chromium oxide layer disappears in local areas.  Thanks to the oxygen in the air, passivation of the material will occur spontaneously in those areas through the formation of a new layer of chromium oxide.  This is known as the ‘self healing effect’ although this mechanism can be badly disrupted in the presence of chlorides.

The Solution

It is vital that stainless steel products and fabrications are clean when they go into service and kept clean whilst in service.  In particular weld areas must be free from discolourisation and contamination plus any mild steel contamination that may have occurred during fabrication must be completely removed. 

 

The following pages detail products that are proven to be the best available for cleaning and protecting staineless steel as well as maintaining its attractive appearance.

 

The subsequent pages provide a more detaled technical explanation of the situation.


Last Datasheet Revision

6 September 2017

Disclaimer

This Data is indicative only and as such is not to be relied upon in place of the full specification. In particular, mechanical property requirements vary widely with temper, product and product dimensions. All information is based on our present knowledge and is given in good faith. No liability will be accepted by the Company in respect of any action taken by any third party in reliance thereon.

Please note that the 'Datasheet Update' date shown above is no guarantee of accuracy or whether the datasheet is up to date.

The information provided in this datasheet has been drawn from various recognised sources, including EN Standards, recognised industry references (printed & online) and manufacturers’ data. No guarantee is given that the information is from the latest issue of those sources or about the accuracy of those sources.

Material supplied by the Company may vary significantly from this data, but will conform to all relevant and applicable standards.

As the products detailed may be used for a wide variety of purposes and as the Company has no control over their use; the Company specifically excludes all conditions or warranties expressed or implied by statute or otherwise as to dimensions, properties and/or fitness for any particular purpose, whether expressed or implied.

Advice given by the Company to any third party is given for that party’s assistance only and without liability on the part of the Company. All transactions are subject to the Company’s current Conditions of Sale. The extent of the Company’s liabilities to any customer is clearly set out in those Conditions; a copy of which is available on request.

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