Stainless steels are a type of material that exhibits a unique set of properties. The reaction between the chromium in the steel and the oxygen in the atmosphere forms a chromium oxide film on the surface, protecting the stainless steel. When the surface is damaged, the film immediately repairs itself in the presence of oxygen. As will be discussed later in this brochure, this protective layer can be modified by chemical treatment to provide permanent metallic colours.
Stainless steels are very suitable for construction applications. They are easy to shape and can be welded.
Production surfaces
Production surfaces are the basic supply requirement for all stainless steel flat surfaces, whether hot or cold rolled. They are universally used for standard construction components, but also form the basis for subsequent surface treatments to meet the demanding architectural requirements.
Four special surface designs are important for architectural and construction applications. These are; 1D, 2D, 2B and 2R.
1D
This surface condition, where the hot rolled and annealed production shell has been removed, is classified as a 1D surface. This surface, seen on thick sheets and plates, is somewhat rough and has very low reflectivity. It is primarily used for non-decorative purposes where less visual features are required, such as support systems and structural applications.
2B
Manufactured like 2D, but with a final light rolling using finely ground dies, the surface is given a smooth, reflective, grey sheen. This is the most common finish today and forms the basis of many ground and brushed finishes.
2D
This is a more refined finish than 1D and is achieved by cold rolling, heat treating and pickling. The low reflective matt finish is suitable for industrial and engineering needs, but is suitable for architectural applications of little aesthetic importance.
2R
A highly reflective surface is obtained by bright annealing in an oxygen-free atmosphere followed by cold rolling with stone rolls and bright annealing. This very smooth surface is much less susceptible to airborne contaminants and moisture than other manufactured surfaces and is easy to clean.
Mechanically Ground and Brushed Surfaces
The number of additional surface treatments can be minimised by selecting, as a starting point, the production finish that is closest to the desired result.
The finishes applied will have a direct impact on the surface appearance and environmental performance of the metal and should be selected with care. Mechanically ground and brushed finishes involve the use of abrasives that effectively cut the surface of the steel to a certain extent.
A number of one-way surface options are available, depending on the original stainless surface, the type and texture of the strips and the nature of the polishing method used.
Reference samples should be prepared to the accepted standard and should be available to both parties.
Mechanically applied finishes may include wet sanding or dry (grit-faced) strips or brushes, which provide a high finish, low roughness and a silky gloss finish. However, the cost is somewhat high and there may be a minimum supply requirement. Manufacturer sample panels are available showing the range of surfaces.
2G
A low reflective, unidirectional uniform surface. The rough surface is limited to interior applications.
2J
This surface is obtained by polishing belts and brushes. It is unidirectional, non-reflective and suitable for interior architectural applications.
2K
This smooth reflective surface is suitable for many architectural applications, especially for serrated sides where atmospheric performance is important. The finish is obtained by the use of fine grit belts or brushes, giving a clean cut finish with a maximum roughness of Ra=0.5 microns.
2P
A highly reflective, flat mirror finish obtained by polishing and buffing with a soft cloth and special polishing compounds. This surface reflects a very distinctive image.
Patterned Surfaces
Patterned rolled proprietary surfaces are obtained by rolling or pressing the thin-gauge coating and sheet with patterned dies that effectively solidify the sheet, resulting in possible cost savings and overall weight reduction.
They are particularly suitable for large flat areas such as coatings where the optical aberrations of the visual surface, known as “wet canning”, are significantly reduced.
There are two main types of rolled patterns: 1-sided patterns, where the back is blank, are classified as 2M; 2-sided patterns, where the pattern is also printed on the back, are classified as 2W.
2F
This low reflective matte surface is required on both sides of the sheet, with the surface graded. The material is annealed, pickled and passed onto profile blasting mills.
In public areas where surfaces are susceptible to accidental impacts and scratches, such as building entrances, elevator interiors and airport terminals, patterned surfaces are the surfaces that show the least damage.
2M
Visually appealing surfaces, textured on only one side, designed for many architectural applications.
2W
Rolled and pressed patterns are obtained with male and female dies and dies.
Profile Sprayed Surfaces
Profile sprayed surfaces produce unidirectional, uniform, low reflective surfaces that contrast visually with finely ground surfaces. Materials used for spraying include stainless steel particles, ceramic profiles, aluminum oxide, segmented screw barrels and glass, each of which increases the variety of surfaces available. Conventional iron and carbon steel should never be used as this can seriously contaminate the surface of the stainless steel, and sand can contain ferrous materials that can contaminate the surface and is generally not recommended for use on stainless steel. Austenitic stainless steel is hardened through the surface spraying process. However, this process can increase or decrease stress in the sheet or fabricated component. In some cases, spraying may be necessary on both sides to equalize the stress. Advice and information can be obtained from expert surface companies.
