Stainless steel and aluminum are two metals very important to the foodservice industry. So which is better? Well, that depends. Each metal is better for different applications. When we attended Vollrath University recently, they broke the two down and explained which is better for specific uses.
What is Stainless Steel?
Stainless steel is made up of iron, chromium, nickel, manganese, and copper. This iron alloy has a minimum of 10.5 percent chromium, an agent that provides corrosion resistance. It’s non-porous and non-corrosive with higher resistance to rust as well.
What makes stainless steel less corrosive is a “passive” layer of chromium oxide that the chromium forms.
Vollrath explained this is 12 to 30 percent chromium and too thin to be visible but protects the metal beneath. Nickel assists in the process and restores itself with oxygen. So—as long as the passive layer or film stays intact, isn’t broken or contaminated, a product remains stainless.
But can it still stain? Yes. A scratch to the surface can lead to rust. So can heated water that leaves deposits and chlorides found in salt, water, cleaner and quaternary salts. But even though the possibility to stain is there, Vollrath reminded us it’s called stainless because it won’t rust, corrode or rust as easily as ordinary steel.
Types of Stainless Steel
Austenitic Stainless Steel
Comprised of alloy with nickel and chromium. There are the 200 and 300 series stainless steels and are the most specified grades in foodservice. Austenitic stainless steels are corrosion and water resistant. They are non-magnetic as well.
200 series: In general, this type of stainless steel is commonly used for wheel covers and door hardware. Being more specific to the foodservice industry, these are commonly found in counters, oven parts, covers and tray slides.
300 series: These are typically found in steam table pans, sinks, food processing equipment, and Bains Marie. The 300 series contains 301 and 304 stainless steel.
- 301 stainless steel is 17 percent chromium and 6 percent nickel (otherwise known as 17/6). As there is less nickel, it isn’t as corrosion resistant as 304, however, Vollrath said it is more difficult to form and is stronger because it has less nickel.
- 304 stainless steel is 18 percent chromium and 8 percent nickel (otherwise known as 18/8). It resists most oxidizing acids and is very corrosion resistant.
Ferritic Stainless Steel
This type of stainless steel does not contain nickel and does not have the same corrosion resistance found in the 200 and 300 stainless steel. It’s also magnetic.
400 series: In general, type 430 stainless steel (explained more in detail below) is found in automotive trim, architecture, and mufflers. Specific to the foodservice industry, this type is common in flatware, carts, structural parts, and steam tables.
- 430 stainless steel is 16 to 18 percent chromium and contains no nickel (otherwise known as 16/18-0). Despite not having any nickel, it is quite corrosion-resistant but not as much as the 300 series.
What Is the Difference Between Stainless Steel Gauges?
In addition to series, stainless steel gauge is another factor that will determine the durability of your stainless steel equipment. Common gauges include 14, 16, 18, 20, and 22 gauge. The lower the gauge, the thicker the stainless steel, which means it’ll be much more durable – and also more expensive. Therefore, a 16 gauge stainless steel equipment will be able to put up with more of the crazy demands of high volume rushes, and typically last longer, than a 20 gauge piece.
Is Stainless Steel Magnetic?
Some stainless steel is, while others are not. So, which types of stainless steel are magnetic? Ferritic stainless steel is traditionally magnetic while austenitic stainless steel is not, given ferritic’s much higher concentration of iron in its construction process. Therefore, magnets won’t work on all types of stainless steel.
What is Aluminum?
Vollrath explained aluminum has higher oxidation and corrosion resistance because of passivation. When aluminum is oxidized, its surface will turn white and will sometimes pit if used in some extreme acidic or base environments.
Aluminum is more lightweight than other metals and is strong. It’s particularly strong when blended with alloy elements, hence being ideal for structural parts and equipment housings as well as heavy gauge cookware.
Aluminum is also a great conductor of heat. Vollrath said it has excellent thermal conductivity which makes it ideal for cookware and equipment where good heat conductivity is needed. It is also less expensive than stainless steel.
Types of Aluminum Metal
Similar to stainless steel, there are different types of aluminum, each different for specific foodservice applications.
Vollrath said this type of aluminum is 99 percent pure. It’s soft, forms easily and can’t withstand tough commercial duty applications or high heat applications without warping. This type of aluminum also dents and scratches easily.
This type of aluminum is one to 1.5 percent manganese. It forms easily and items of this type hold up extremely well for normal use, however, may still be too soft for commercial/heavy duty use.
This type of aluminum is one to 1.5 percent manganese and 1 percent magnesium. It’s more difficult to form than the 1100 or 3003 and Vollrath said is much more impervious to sever use. It’s tougher and lasts much longer than 3003. This is a type of aluminum ideal for quality cookware, bakeware, and tougher commercial equipment applications.
Is Aluminum Magnetic?
No. Aluminum is a metal, and magnetic materials are always made of metal, but it’s important to note that not all metals are magnetic. The degree of magnetism often depends on the concentration of iron. Therefore, many types of steel are magnetic, but since aluminum is a metal that does not contain iron, it is not magnetic.
Recap: Stainless Steel vs. Aluminum… Which is Better?
Vollrath wrapped up this section with the following information to help determine which metal is best for specific applications.
Stainless steels are harder and are especially harder to form than aluminum.
Aluminum has a much better thermal conductivity than stainless steel.
Aluminum is more porous and prone to surface scratches and dent, which makes it harder to clean.
Effect of Foods
Stainless steel is less reactive to foods. Aluminum can react to foods that may affect color and flavor.
Aluminum is typically lower in price than stainless steel.
The gauges for each are different.
If you found this interesting, you may also enjoy our article on choosing cookware, which breaks down which construction material is best for specific needs, covering the differences between aluminum vs. stainless steel cookware, cast iron, carbon steel, clad, and induction cooking supplies.
In addition, our bakeware guide helps you determine the differences between using aluminum, stainless steel, and aluminized steel for your bakeware.