Annealed and pickled finish – 2D
Cold-rolled, annealed and pickled steel sheet, finish 2D (D=Dull), has a semi-matt silver-grey surface, and has an Ra value in the order of 0.2-1 µm. Generally, the Ra value increases with greater sheet thicknesses. It is used mostly for industrial equipment and for the manufacture of pipes and tubes for the process industry.
Skin passed finish – 2B
A cold-rolled and annealed sheet may be given a smoother surface by means of a further light rolling between highly polished rollers. The result is a semi-bright grey surface which is termed skinpass-rolled or finish 2B (B=bright) and has an Ra value of between 0.1 and 0.5 µm. Skinpass-rolled steel sheet is often used for process equipment within the food industry when a surface which is easy to keep clean is required.
Bright annealed finish – 2R (BA)
If, after cold rolling, the sheet coil is annealed in a protective atmosphere (e.g. hydrogen and nitrogen) that prevents oxidisation of the surface, pickling is not needed. This surface quality is termed bright annealed finish 2R (also known as BA). Since the surface has not come into contact with pickling acids, it attains a brighter finish than either of the above examples, and an Ra value of 0.03-0.2 µm. It is used for the manufacture of household equipment and appliances (dish washers, washing machines, etc.), this product is also offered in precision strip, i.e. to applications where there are very high requirements on thickness tolerances.
Bright pickled – 2BB
The bright pickled 2BB surface is a mirror surface finish, available for the ferritic grade EN 1.4016, providing an alternative to Bright Annealed (2R/BA) finishes on most of the applications where a smooth surface and a bright appearance are needed. Typical applications for the finish 2BB are washing machine drums; inside parts of the dishwashing machines etc. Thanks to the low surface roughness, the finish 2BB is a perfect material for further polishing. Additionally, the smooth surface makes it easy to clean and hygienic.
Grade EN 1.4016 (AISI 430) is suitable for all the common forming methods used for the stainless steels and especially for deep drawing applications. Mechanical properties and formability of the finish 2BB are comparable to surface finishes 2B and 2R/BA. Due to the fact that surface roughness of the finish 2BB is lower than that of 2B, some modifications on lubrication during forming might be needed.
The process practice is identical to the 2R/BA-process except for the soft annealing and pickling steps. The soft annealing is carried out without any protective atmosphere. Careful control of the annealing process enables the use of very gentle pickling of the annealing oxides, and the mirror finish from cold rolling is maintained. The reflectivity of the surface is further increased by skin-pass rolling.
Work hardened stainless steel – 2H
High strength austenitic stainless steels are made by controlled cold rolling reduction. By not annealing after rolling, the high strength resulting from cold working is kept in the finished product. Achieved strength properties depend on steel grade and used rolling process parameters.
The 2H surface has typically a fairly smooth reflective finish. By request some 2H high strength steel products can be delivered as polished / brushed surface finish. The 2H finish is also known as finish TR (ASTM denotation).