Stainless steel sheet suppliers have many grades of stainless steel available for consumers to choose from. No doubt, the choices can be overwhelming to the uninitiated. However, knowing what grade to use will ultimately be determined by what environment the stainless steel will be used in. In other words, what degree of corrosion resistance will be needed by the consumer depends on which industry the consumer is in. Will it be an indoor or an outdoor environment? Will it be used in a bathroom, a kitchen, or for architectural paneling or automotive parts? Herein is a concise guide to assist our customers to choose the right size, grade, and finish of stainless steel for whatever the job may be.
Stainless Steel Sheet Thickness
Let’s consider first that stainless steel sheet metal is formed by an industrial process into thin, flat pieces, which can be cut and formed into a variety of shapes. Many everyday objects all around us are fabricated from stainless sheet metal. The thicknesses of the sheets vary up to 6mm (.25 inches). Any thickness higher is classified as plate and is used for other industrial or commercial purposes.
With the exception of the U.S., sheet metal thickness is specified in millimeters. In the U.S., the thickness of sheet metal is commonly specified by gauge. The larger the gauge number, the thinner the metal. Atlantic Stainless offers standard sheet sizes of 4’ x 8’, 4’ x 10’, and 5’ x 10’, but will customize to any size. Cut sheets are generally sheared to size, but we can waterjet, plasma, or laser cut any sheet to any size upon special request.
What Grade Should Your Stainless Steel Sheet Be?
There are many grades available of stainless steel. Atlantic Stainless offers sheets in the following grades: 304, 304L, 316/316L, 301 Ann, 301QH, 301HH, 301FH, 302, 309, 310, 321, 330, 347, 409, 410, 430, 600, 625, 718, 15-5, 17- 4, 17-7, A286, and 2205.
The grades are determined by a chemical formula. Of all the stainless steel alloys, the 300 series grade is the most commonly used, of which, the 304 alloy austenitic steel is the most common type. Its versatility and strength make it the most widely used, and is available in more forms and finishes than any other grade of stainless steel. Approximately 70% of all stainless steel made is austenitic, a nonmagnetic, solid solution of mostly iron and carbon which relates to its primary crystalline structure.
The 300 series grade is the most corrosion resistant, most ductile, and can be easily formed and welded. The 304-grade stainless steel is the ideal grade to use not only because of its incredible welding characteristics, but also because of its balanced austenitic structure. It’s widely used in many industrial, architectural, and transportation related applications.
The level of corrosion resistance, or what makes stainless steel stainless, is related to the amount of carbon and chromium used in the finished alloy. The corrosion resistance of the many grades of stainless steels stems from alloying the base iron with at least 10.5 % chromium and a maximum of .15% carbon. The chromium provides a passive film of chromium oxide that rises to the surface, coats the steel, and blocks corrosion from spreading into the metal’s internal structure. Therefore, increasing the amount of chromium gives an increased resistance to corrosion.
Stainless Steel Sheet Finishing Makes the Difference
In addition to the many grades of stainless steel, the sheets come in a variety of finishes depending on the application that stainless steel is used for. The finishes are numbered or alpha-coded: 1, 2B, 2D, 2BA (or simply Bright Annealed) 3, 4, 6, 7, 8, and TR for Temper Rolled. At Atlantic Stainless, stainless steel sheets come in both a standard 2B finish and various polished finishes. Polished surfaces range from the standard #4 to a mirrored finish #8 and are usually covered with a removable vinyl coating.
The #4 “Brushed” finish is the most common. Easily recognizable, you’ll find the finish on nearly all stainless steel appliances. The brushed look has a bright finish and is characterized by short, uniform, parallel polished lines, with a visible directional “grain.” It is designed for daily use and to hide scuff marks, fingerprints, scratches, and etcetera.
The #8 mirror-like finish has the most reflective, highly polished surface of any stainless steel. The finish is arrived at by polishing with successively finer abrasives and then buffing extensively until all grit lines from preliminary grinding operations are removed.
Finally, stainless steel sheet is typically sold in the annealed condition. Meaning, when stainless steel is annealed, it must be heated to a temperature below its melting point, then cooled slowly in order to make it less brittle and more malleable. That way it brings the sheets to a desired consistency, texture, or hardness.
As stainless steel sheet suppliers, we offer a wide selection of grades, cuts, sizes, and finishes that can be customized for the job at hand. If you can’t find the size or grade you’re looking us feel free to contact us for assistance at 800.876.2700.
