A Stainless Steel Sheet Suppliers Guide to Purchasing Steel Sheets

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.

Stainless steel, known primarily for its corrosion resistance, is used in a wide variety of applications. The diverse range of grades allows it to accommodate various applications across many different industries. However, having so many grades requires the know-how to select the appropriate one for the job.

Here are 7 things to consider when choosing a stainless steel grade:

• Does it need to have good formability?
• Does it need to be welded?
• Does it need to be machined?
• How much and what type of corrosion resistance is desired?
• Does it need to be heat treated?
• What are the strength requirements?
• What are the typical applications?

Does the stainless steel need to have good formability?

If the application requires good formability, avoid the martensitic group of stainless steels. Try an austenitic grade such as 304 or a ferritic grade such as 430. Martensitic stainless steels like 410 tend to be brittle and are not readily formable. Austenitic stainless steels are usually the best choice when it comes to formable stainless steels.

Does the stainless steel need to be welded?

Welding stainless steel is very different than welding carbon steel, and can lead to problems such as intergranular corrosion, hot cracking and stress corrosion cracking. The most weldable stainless steels are typically in the austenitic group. When welding austenitic stainless steels, grades such as 304L or 347 should be used. Grade 304L has lower carbon while 347 has niobium stabilizers added to it which help to deter intergranular corrosion. Ferritic stainless steels such as grade 430 or grade 439 are also readily weldable, as are Duplex stainless steels. Martensitic stainless are generally not suitable for welding, however, some martensitic stainless steel grades with lower amounts of carbon can be welded. With precipitation hardened stainless steels, care should be taken to ensure that the original mechanical properties are not compromised during the welding process.

Does the stainless steel need to be machined?

If machining is required, special considerations must be accounted for when working with stainless steel. Most grades of stainless steel can be machined, however, stainless steel is very susceptible to work hardening. The machining process must be optimized to work at a rate that helps alleviate this issue, and the tools used for machining must also be kept in good working condition. Similar to carbon steels, sulfur can be added to increase machinability; grade 303 is an example of this. It is very similar to grade 304 except that sulfur has been added to it for machining purposes. Grade 416 is example of a ferritic stainless steel with added sulfur.

How much and what type of corrosion resistance is desired?

Stainless steel is usually chosen for its corrosion resistant properties, but it is important to know that different grades provide different amounts of corrosion resistance. Austenitic stainless steels generally provide the most corrosion resistance because of their high amounts of chromium. This makes grade 304 an excellent choice when corrosion resistance is important. Grade 316 is similar to grade 304, but it has molybdenum as part of its chemical makeup, further increasing its corrosion resistance. Ferritic stainless steels and martensitic are generally more affordable than austenitic stainless steel because they have less nickel and sometimes less chromium than austenitic stainless steels, which can result in a loss of corrosion resistance. Duplex stainless steels can be used to avoid the stress corrosion cracking associated with austenitic stainless steels.

Does the stainless steel need to be heat treated?

If the stainless steel is going to be subjected to heat treatment, it is important to know how the various grades of stainless steel can be affected. For the most part, austenitic stainless steels and ferritic stainless steels are non-hardenable when heat treated. The heat treatable stainless steels are typically martensitic or precipitation hardened. Examples of these are grade 440C and 17-4 PH, respectively.

What are the strength requirements of the stainless steel?

Very high strengths can be achieved with martensitic stainless steels, like grade 440C; and precipitation hardened stainless steels, like grades 17-4 PH and 15-5 PH. Austenitic stainless steels, such as grade 316, can provide high strengths as well, though not as high as the martensitic grades. Austenitic stainless steels also have more nickel than other stainless steels, so a grade like 316 will have greater toughness and ductility than ferritic and martensitic stainless steels. Duplex stainless steels can provide ferritic stainless steel properties while still maintaining a ductility and a toughness close to austenitic stainless steels.

Typical Applications

Sometimes the best way to find out what grade of stainless steel should be used is to see what has been used in the past. Here are some examples of where certain grades of stainless steel are used.

Ferritic Stainless Steels:

• Grade 409: Automotive exhaust systems and heat exchangers
• Grade 416: Axles, shafts, and fasteners
• Grade 430: Food industry and appliances
• Grade 439: Automotive exhaust systems components

Austenitic Stainless Steels:

• Grade 303: Fasteners, fittings, gears
• Grade 304: General purpose austenitic stainless steel
• Grade 304L: Grade 304 applications that require welding
• Grade 309: Applications involving elevated temperatures
• Grade 316: Chemical applications
• Grade 316L: Grade 316 applications that require welding

Martensitic Stainless Steels:

• Grade 410: Generable purpose martensitic stainless steel
• Grade 440C: Bearings, knives, and other wear resistant applications

Precipitation Hardened Stainless Steels:

• 17-4 PH: Aerospace, nuclear, and chemical applications
• 15-5 PH: Valves, fittings, and fasteners

Duplex stainless steels:

• 2205: Heat exchangers and pressure vessels
• 2507: Pressure vessels and desalination plants

Disclaimer: Please note this information is not to be used for design purposes, and in no event shall MSFFC be liable for any damages arising from the misuse of this information.