The stainless steel Surface Finishes of stainless steel affects much more than just its aesthetics. Performance, reliability and other factors can be greatly affected.
No matter the application or end-use of the stainless steel, its surface finish should be carefully chosen to best meet the requirements at hand. That’s because, in addition to providing the desired visual appeal, the choice of finish affects corrosion resistance, characteristics such as electrical properties, impacts weldability, manufacturing operations, and contributes to various economic considerations.Whatever the stainless steel’s application or end-use, its surface finish should be carefully selected to best meet the requirements. It’s not just about aesthetics, but also corrosion resistance, electrical characteristics, weldability, manufacturing processes and various economic aspects.
Read on to find out the subtle differences between each finish and understand how suppliers may differ.
Finish is the visual appearance of the metal and is produced by a variety of processes such as rolling, polishing and blasting.Finishes range from dull to bright and include special textures mechanically applied for highly specialised applications.
Factors such as production route, material thickness, roll surface finish, cleanliness and mechanical abrasion can all affect surface finish.
Surface treatment is usually referred to by industry standard names based on the process route (not the look) and is different for sheets (>24″ width) and strips (<24″ width).
Whether hot or cold rolled, these finishes are the basic delivery condition for all stainless steel sheet products. Universal in many applications, they are the starting point for mechanical polishing and other finishing processes. For maximum corrosion resistance, most are acid cleaned (pickled) to remove scale formed during hot rolling and annealing (bright annealed is the exception!).
A bright annealed finish is a cold rolled finish which is then annealed in a controlled inert gas atmosphere to prevent scale formation during the annealing process. This finish is not an acid pickling finish.A thin oxide film forms during annealing, making pickling unnecessary. Applications include trimming tools, surgical equipment and cooking utensils.
Any discussion of surface finish would be incomplete without mention of surface roughness. Surface roughness is a measure of the texture of a finished surface. RA (average roughness) is the most common in North America.It is the average of surface peaks and valleys over a specified sample length. What is the surface roughness of stainless steel? Values are usually given in microinches or micrometers.
Rz is the average of the highest peak to the lowest valley over 5 sample lengths. It is the most commonly used roughness measure in Europe.
Surface roughness can have a significant impact on material durability and performance and must be carefully considered and controlled.
