Stainless Steel: Everything You Wanted To Know But Were Afraid To ...

Even if you are a relative newcomer to the foodservice industry, you have heard the term “stainless steel.”  But even industry veterans are often undereducated about the finer points of stainless steel and its uses. For such a common material, there is a lot of potential confusion. So let’s get started exploring the finer points of stainless steel and its associated uses.

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Table of Contents

• What is Stainless Steel?
• Can Stainless Steel Rust?
• Gauges Explained
• Grades of Stainless Steel Explained
• Specific Steel Types Found in Foodservice Operations
• Is Galvanized Steel the Same as Stainless Steel?
• Cleaning Stainless Steel

What is Stainless Steel?

Stainless steel is not just one thing. It is a term used for a group of iron-based alloys (a metal made by combining two or more metallic elements) that contain a minimum of 10.5% chromium. This combination with chromium is what gives stainless steel its resistance to corrosion. The chromium forms an ultra-thin layer on the steel that is referred to as the “passive layer.” This passive layer is the key to preventing rust and other corrosion.

In addition, the alloy can only have a maximum of 1.2% carbon to be considered stainless. Beyond that, the alloy can contain a number of other elements in varying amounts including nickel, silicon, manganese, titanium, molybdenum, nitrogen, niobium, and others.

Suffice it to say that stainless steel is a combination of metals and other elements. It is the different combinations of these materials that give rise to the different properties of stainless steel.

Can Stainless Steel Rust?

There is a common misconception that stainless steel is some sort of miracle metal that never rusts. This is simply untrue. Because of its chemical make-up, stainless steel is less likely to rust. But it is possible.

You should also be aware that rust is only one type of corrosion. In a restaurant setting, there are any number of chemicals or other substances that can cause corrosion. A common type of corrosion referred to as “pitting” can occur when a stainless surface is not properly cared for or is exposed to corrosive agents for too long. Pitting is just what it sounds like. It appears as tiny pits on the surface of the steel and, left unchecked, can affect both the look and performance of the steel surface.

However, by choosing the right type of stainless steel for your application and applying basic care and maintenance, you can greatly reduce the likelihood of any type of corrosion.

Should You Use a Flatware Retriever?

Gauges Explained

Gauges of stainless steel are the thing that seems to most confuse people. With a lot of things, we think that a higher number is better. So it is natural for people to believe that a higher gauge of steel is better. Wrong!

The gauge refers to the thickness of the stainless steel. Again, you might think that higher numbers indicate thicker steel. But unlike traditional scales, lower numbers indicate thicker sheets of metal. So a 14 gauge stainless steel is vastly more durable than a 22 gauge steel.

Choosing the proper gauge of steel for your application is extremely important. For example, a lighter gauge steel may be perfectly fine for a small hand sink. But for larger, deeper sinks, a heavier gauge steel will be required.

Similarly, as we discussed in our article on equipment stands, you need to understand how you will be using your tables and stands to make the best choice for the gauge of steel required.

Grades of Stainless Explained

While gauge refers to thickness, the grade of steel is a reference to its components and the properties of the steel that arise from using various components. To begin, there are 3 terms you should be familiar with:

Austenitic Steel

Austenitic Steel is the most commonly used grade of stainless. It is composed of chromium and nickel (though some grades may substitute  manganese and nitrogen for most of the nickel content). Austenitic steel is non-magnetic (which may be important to you if you use a flatware retriever). It is considered easy to work with and is found in a wide variety of applications in a commercial kitchen.

Ferritic Steel

Ferritic Steel is a magnetic steel that has a low carbon content. It is not as strong or corrosion resistant as austenitic grade. This is the second most commonly used grade of stainless steel.

Martensitic Steel

Martensitic Steel is much less frequently seen in foodservice, this grade of steel is magnetic and is defined by its low level of nickel and moderate level of carbon.

Duplex

There is a potential 4th category worth mentioning called Duplex. Duplex stainless steels are a more recent addition to the family of stainless steels. As the name might imply, the duplex grade consists of two phases: austenite and ferrite. Duplex stainless steels have not been extensively used in foodservice to date.

Specific Steel Types Found in Foodservice Operations

These different grades have been further defined by the Society of Automotive Engineers (SAE). These grading definitions indicate the composition of the steel, its properties and the standards it must follow.

SAE 304

SAE 304 is the most commonly used grade of austenitic steel. It is typically composed of 18% chromium and 8% nickel (with some manganese thrown in for good measure). Because of this composition, you will sometimes see this referred to as 18/8 steel, especially in reference to flatware. It is highly resistant to corrosion, but it is non-magnetic (again, important if you are using a magnetic flatware retriever). SAE 304 is widely used in the foodservice industry for sinks, work tables, coffee urns, stoves, refrigerators, and equipment stands. It is also used in numerous other smallwares such as cooking utensils, pots, pans, and flatware.

SAE 201

SAE 201 is also an austenitic steel similar to 304 but is less expensive. It provides many of the same benefits as the most expensive 304 grade so it has begun to gain wider acceptance in the foodservice industry.

SAE 430

SAE 430 is an austenitic steel that contains no nickel yet is resistant to corrosion because of its relatively higher chromium content. It is most commonly used for goods that are to be used in lower corrosive environments and conditions. You may see it in lower end sinks and tables but is also sometimes used for panels in refrigerators and ovens.

SAE 316

SAE 316 is a ferritic steel that was originally specified for the medical industry. Though infrequently used in foodservice, it is magnetic and highly resistant to corrosion. Its properties make it more expensive than other steel choices and is more difficult to work with for manufacturers. Therefore it is only seen in specialize products, especially those used in highly corrosive applications.

If you want to learn more, please visit our website Colored Stainless Steel Sheet.

Is Galvanized Steel the Same as Stainless Steel?

The short answer is no. Galvanized steel is just regular steel that is coated in zinc to prevent corrosion. And as we noted above, stainless steel is the blending of steel with chromium (and other metals) to create a new alloy.

Galvanized steel is weaker than stainless steel. However, it is cheaper and therefore is used in a number of ways in the foodservice industry. For example, you may find refrigerators that are stainless steel on the outside, but only galvanized steel on the inside. While this might be acceptable for some uses, a full stainless steel interior is often preferred for commercial applications as seen in professional foodservice operations.

Cleaning Stainless Steel

As we have discussed, stainless steel is resistant to rust and other corrosion due to its chromium layer. It is important to maintain your stainless pieces to avoid any breakdown of this passive layer that could lead to corrosion. Proper cleaning is essential.

If the stainless piece you need to clean came with instructions from the manufacturer, then by all means follow those instructions. But if you have no other guidance, here are a few simple tips for cleaning your stainless steel.

First, be cautious about using abrasive cleansers. The grit in some cleansers can scratch the stainless surface. This can actually make matters worse as it can lead to further breakdown and ultimately more corrosion.

If you are  trying to remove fingerprints or smudges to improve the cosmetic appearance of your stainless, try simply wiping with a soft, dry cloth. You can also try simply using water or a damp cloth as well. Just be sure to dry the surface thoroughly.

Commercial Reach-In Refrigerator & Freezer Buying Guide >

Cleaning Solutions

If you are trying to remove dirt, grease or other contaminates, you can use a mild detergent (like the one that “takes grease out of your way”). A soft cloth, sponge or even paper towel may be effective. And again, be sure to dry the surface.

You can also try a light vinegar and water solution or a baking soda and water solution to help clean surfaces without chemicals. For more stubborn issues, you may need to use a harsher cleaning agent. You might also need to use a different implement like a scrubbing bristle brush or the scrubber side of a sponge. However, it is always best to test any of these solutions out on a small, less visible area of the piece you are trying to clean. Check for scratching or discoloration. Rinse the surface with water after you use any type of cleaner. And, as always, dry the surface when done.

Avoid metal brushes and things like steel wool as they not only have the potential to scratch the surface, but they can also leave behind embedded particles.

The Final Word on Stainless Steel

As a restaurant or foodservice worker, you will see stainless steel everywhere you look. Understanding the types of stainless steel and their appropriate uses is an important skill as you make purchase decisions. Whether it is a chafer, a sauce cup, a line of flatware or a new piece of equipment like a reach-in refrigerator or a six burner range, stainless steel is found in all aspects of a commercial kitchen.

Have any specific questions about stainless steel? Is there something we didn’t cover that you would like to learn more about? Leave us a comment below and we will try our best to assist!

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 .

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.

For more information, please visit Custom Stainless Steel Fabrication.