Getting the best out of stainless steel
While most stainless steel applications function exactly as the designer intended, there are times when this most durable of materials fails to meet the high expectations of the consumer. Normally the causes of these issues are pretty straightforward and, with a little foreknowledge, can be easily prevented. Here a few tips on ensuring you get the best of out of stainless steels.
Typical issues with stainless steel
Problems with stainless steel normally arise because of the long supply chain and manufacturing process that the material goes through. Issues can occur at several key points so it is useful to have some knowledge of the stages involved. The main factors to consider during the process are:
While selecting a grade of stainless steel is commonly recognised as an important step in the process, getting the right surface finish is just as crucial. A polished surface finish will give the best resistance to corrosion. In most harsh environments, coastal and dense urban areas for instance, a polish equivalent to the EN 10088-2 2K (Ra = 0.5 micron maximum), normally made using silicon carbide abrasives, will give sufficient corrosion resistance.
Common surface finishes using 240 grit alumina abrasives give surface roughness Ra values of above one micron. This is not enough to prevent corrosion in some tough environments. Architectural drawings without a specific surface finish can be the cause of major problems in the future. Specialist advice on surface finish should be sought if there are any doubts.
Post fabrication treatments
Because welds in stainless steel almost always produce heat tint (an oxidised surface with a reduced resistance to corrosion compared to its parent metal), post weld treatment is essential. Any good fabrication of stainless steel should always include this process.
Segregation of carbon
In some instances, stainless steel ‘rusting’ is actually the rusting of carbon steel which has contaminated the surface of the stainless steel in the production process. This contamination can emanate from tools, grinding dust, wire brushes, cutting sparks or lifting apparatus. Therefore, carbon steel and stainless steel should be fabricated in separate places. If this is not possible, plastic coatings should be used to protect the stainless steel while carbon steel machinery needs to be meticulously cleaned.
Even if the fabrication processes are completed successfully, bad practices on site can spoil whole projects. Brick and masonry cleaners may contain muriatic acid which can result in major attacks on stainless steel. Any fluid splashes on stainless steel surfaces should be immediately washed off using water.
Maintenance and cleaning
It is important to remember that for all stainless steel’s excellent resistance to corrosion, it still requires cleaning and maintenance just like any other surface.
The correct grade and specialist advice
Probably the most important factor in ensuring the durability of stainless steel is to select the correct grade for its application. The wrong grade can have serious and expensive consequences for your stainless steel. If in doubt, make sure you consult our specialists here at NeoNickel. Contact us today.