Specification and Application of Colored Coated Stainless Steel Plates

Stainless steel plates can be tinted by coating or chemical treatment. Both methods produce durable colored stainless steel plates in normal use, but they might be difficult to repair if damaged, especially the chemical-treated ones. The coating method relies on the introduction of the coating material to the surface of the stainless steel plate, while the chemical treatment changes the thickness and properties of the passivation film. The following mainly introduces the specifications and applications of chemical-treated stainless steel plates.  

Surface coloring of stainless steel plates is usually limited to flake products, although coloring of manufactured parts is also possible. In addition, only the best quality stainless steel plates can be successfully chemically completed on a production basis. The chemical coloring treatment of stainless steel plates uses a mixture of chromic and sulfuric acid, which produces a naturally occurring passivation film on the stainless steel surface depending on the impregnation time. This is a two-stage immersion process that requires accurate control of operating parameters and considerable skill to achieve the desired color consistency. A blackening finish is rarely produced by immersion in a molten dichromate salt bath at about 400℃. The resulting color is the result of the wave interference effect of light reflected from the interface between the surface of the enhanced oxide passivation layer and the passive layer and the stainless steel plate surface. As the film grows, the color grows bronze, blue, black, charcoal, gold, red, purple, and green. The finished thickness of the passivated film is 0.02 microns, with a bronze effect of 0.36 microns, producing a green effect. Austenite 1.4301 (304) and 1.4401 (316) are available in a range of colors including blue, black, bronze, gold, green, and red/purple. A charcoal color effect can be created by treating a satin finish to the same conditions that normally produce blue on a non-finish surface. Ferritic stainless steel 1.4016 (430) material is generally limited in the range of possible colors.