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

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.

Table of Contents

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.

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.

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.

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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.

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 alloys are popular for applications big and small across numerous industries.

There’s a good chance that there is a stainless steel product or piece of stainless steel equipment within a short walk of where you are right now.

But if you’re looking to design a system, create stunning designs, or fabricate parts and equipment, you’ll have to start with basic stainless steel products and work from there.

In this guide, we’re going to look at the most common stainless steel shapes and sizes you’ll encounter and the considerations you should make when determining the ideal product for your next project.

Formats Explored: Stainless Steel Sheets, Plates, and Bars

Before we dive into the various characteristics of alloys, finishes, and other more metallurgic details, we should explore the different shapes and formats in which stainless steel is sold today.

Each will offer different benefits depending on your intended use.

As such, understanding your options can help you to find a format that is most closely matched to your needs and avoid additional costs and time spent on further processing before you can use your stainless steel.

Stainless Steel Sheet

Stainless steel sheet is the most flexible option in most cases–both in terms of sizing and shape and in your ability to form it to fabricate products or meet your design specifications.

Depending on your needs, you’ll find stainless steel sheets in thicknesses up to around 6mm.

Products above this thickness tend to fall into the plate form instead.

If you’re sourcing your sheet from the U.S., you might also find this thickness listed by gauge instead of in millimeters.

In most cases, the stainless steel supplier will offer a range of standardized sizes.

Common sizes include 48-inches-by-120-inches (roughly 122-centimeters-by-305-centimeters), 60-inches-by-120-inches (roughly 152-centimeters-by-305-centimeters), and 72-inches-by-120-inches (roughly 183-centimeters by 305-centimeters.)

However, many suppliers can also offer metal cutting services using plasma cutters, waterjet cutters, and other tools to provide a product that precisely meets your ideal size and shape.

Sheet is ideal when you plan to shape or cut the base stainless form to create lighter-weight parts and equipment.

Most sheets are delivered in an annealed state, providing an excellent balance of strength and malleability.

This means you can often take stainless steel sheets directly from shipping to the press for shaping or welding table for fabrication with minimal preparation or pre-processing.

Since the sheet is often cut into standardized sizes, it’s also easier and more space-efficient to store than some other forms.

However, if you plan to stack or store stainless with a mirror or high-gloss finish, be sure to consider any precautions to avoid marring your product's finish before use.

Stainless steel sheet is commonly used in the chemical, construction, food service, marine, transportation, and textile industries.

Stainless Steel Plate

Stainless steel plates can share many similarities with stainless steel sheets.

However, it starts at higher thicknesses in most cases and is often smaller in overall surface area.

Plate is also available in standard sizes, though these tend to start smaller–around the 12in-by-12in (or 30cm-by-30cm) range and topping out around 48-inches-by-120-inches (roughly 122cm-by-305cm.)


However, like with sheets, you can also order these with custom cuts and sizes to fit your intended application or any special needs you might have.

Keep in mind that thicker pieces will typically mean greater weight when compared to stainless steel sheets of comparable size.

However, this also means increased strength depending on the need.

Stainless steel plate is commonly used in the chemical, construction, food service, marine, transportation, and textile industries.

Stainless Steel Bar

Unlike stainless steel plate or sheets, stainless steel bar comes in various shapes, including round, square, hex along with angle and flat bar and hollow bar.

Their names essentially refer to their shape, giving an easy way to start limiting choices to find your ideal bar type.

Like plate and sheet, stainless steel bars are available in various thicknesses (or diameters depending on the shape.) Standard sizes range from 3mm to 25mm.

Flat bars are often used to help form base plates and brackets or reinforce key areas where plate might otherwise be a poor choice.

Round stainless steel bars (sometimes referred to as stainless steel rounds) are very popular in machining for creating fasteners, threaded tubes or shafts, and other items.

Hexagonal and hollow bars are often used in weight-bearing scenarios and the fabrication of many common structural beam elements–including I beams, H beams, and C beams. However, hexagonal bars can also have machining uses similar to stainless steel rounds, allowing for rapid production of nuts and other fasteners.

Square bars fit well into both categories, providing excellent structural and load-bearing support while also being an ideal shape and format for machining and fabricating various fasteners.

Other Traits and Characteristics to Consider

Of course, when choosing the ideal stainless steel product for your needs, the actual format is just a part of the overall decision.

You also need to determine the best stainless steel alloy, ideal finishes, and other traits that might impact your components' service life and overall fit for your budget.

Grades to Consider

Most plate, sheet, or bar products will be available in a range of alloys, including those in the 200, 300, and 400 series.

However, you might also find that specialized grades are available for specific uses.

300-series stainless steel will provide an excellent balance of cost, weight, fabrication ability, and corrosion resistance in most cases.

However, 400-series steel is popular in food service applications, medical environments, or when looking for a ferritic stainless option.

If you’re looking for more information regarding the various stainless alloys and their traits, be sure to consult our guide to stainless steel grades and families.

Finishing Touches

Finishes are another consideration that can impact overall costs and better align your stainless steel with your intended use.

For example, mirror finishes (#8) might look impressive but quickly pick up fingerprints and show scratches and other wear easier.

As such, if they’re in a high-traffic or touch-heavy environment, you might spend an unreasonable amount of time maintaining that finish.

You’ll also need to take extra precautions when storing the steel or fabricating and assembling to avoid damage. In many cases, a protective liner is recommended to avoid mishaps.

By contrast, brushed finishes (#4)–popular in food service and appliance use–offer a clean, professional appearance with far fewer cleaning and maintenance requirements.


On the other hand, if you plan to do extensive fabrication or welding, you might find it best to apply a finish yourself.

In these cases, opting for a product with a 1, 2B, or 2BA finish could reduce costs and allow greater flexibility.

For more information, including typical uses and any considerations to keep in mind, be sure to consult our guide to stainless steel finishes.

Fabrication Methods

This final consideration touches on points related to virtually everything considered so far.

If you’re planning to cut, weld, rivet, or modify the steel in any way, be sure to consider any stresses applied to the steel and potential treatments which might be required to return the steel to an ideal state.

For example, extensive welding or the heat of plasma cutting might require you to consider pickling, electropolishing, or other heat treatments to ensure that the passive layer is effectively restored and promote optimal corrosion resistance.

Riveting or fastening will require you to consider any hardware used to minimize galvanic corrosion risks.

Tapping or threading stainless steel bars and other parts will likely require attention to machined areas to ensure complete restoration of the passive layer and avoid corrosion risks.

By understanding these factors in advance, you can avoid maintenance surprises, optimize costs, and pick

Summary

• Stainless steel sheet provides a relatively thin stainless product ideal for fabrication and forming.
• Typically thickness is measured in millimetres, with sheet topping out around a thickness of 6mm.
• Sometimes thickness is listed as gauge or inches instead.
• Sheet typically comes in standard pre-cut sizes ranging between 4 feet (1.2m) and 6 feet (1.8m) wide and up to 10 feet (3m) long.
• Customized sizes are offered by suppliers with cutting services in most cases.
• Sheet is often delivered in an annealed state.
• Stainless steel plate is a thicker stainless steel product, often available in smaller sizes than plate due to its increased weight.
• This thickness might also limit your custom sizing options due to cutting requirements.
• However, the increased thickness can mean increased strength depending on your intended application.
• Stainless steel bar is available in a variety of shapes and sizes.
• Standard options include flat bars, round stainless steel bars, hexagonal bars, square bars, and hollow bars.
• Bars can meet a variety of needs, seeing use across nearly all industries.
• Your choice of stainless steel grade can further influence the traits of your stainless steel bar, plate, or sheet.
• 300-series steels are good all-around options for balanced cost and corrosion resistance.
• 400-series steels are excellent for ferritic options and are commonly found in food service and medical environments.
• Finishes can also play a role in optimizing your stainless steel bar, plate, or sheet choice. Mirror finishes, for example, look great but show fingerprints and wear easier. On the other hand, brushed finishes are fantastic for avoiding smudges, knicks, and marring.
• If you’re planning to cut, weld, rivet, or modify your stainless steel in any way, be sure to consider any additional treatments or special methods required to ensure optimum corrosion resistance and strength.
• Pickling and electropolishing can help to eliminate the impact of heat exposure.
• Taking care to avoid contamination and encouraging passivation can help recover from damage resulting from fasteners or threading.

For more than four decades, Unified Alloys has helped supply industries large and small throughout Canada and North America. If you’re searching for 

By understanding these factors in advance, you can avoid maintenance surprises, optimize costs, and pick stainless steel products that are best suited for your uses and environment.For more than four decades, Unified Alloys has helped supply industries large and small throughout Canada and North America. If you’re searching for stainless steel bar, plate, or sheet products , our comprehensive selection and experienced sales analysts are ready to help! Contact us today to discuss your needs.