Steel vs. Stainless Steel - Consider the differences in corrosion resistance and cost
February 11, 2020
Steel and stainless steel are both reliable metals found in a wide range of products, from substantial applications to very small parts. So, which one is better? The answer is “it depends!”
Steel’s affordability makes it an ideal metal for many projects. It’s typically used in infrastructure, ships, appliances, weapons, and automobiles. Stainless steel, on the other hand, is more expensive, but has a non-reactive, bright finish, and can often be seen in cookware and cutlery, surgical instruments, industrial equipment, and outdoor site furnishings.
Steel and stainless steel are not interchangeable, as their properties and advantages differ. Before selecting one alloy over the other, it is important to identify what the metal will be used for—and then understand the differences in aesthetics, properties, and cost.
Corrosion-resistant stainless steel is used for cookware and cutlery, as well as for commercial kitchens.
Steel is created by adding iron to carbon, which hardens the iron. Various impurities such as sulfur, silicon, phosphorous, and manganese are removed from iron during the steel production process. Steel generally has a lower carbon content than stainless steel, making it slightly stiffer and stronger.
Stainless steel production follows the same steps as steel production, but takes it a step further by adding chromium, nickel, nitrogen, and molybdenum. The chromium content is key to making it stainless steel, and to qualify as stainless must be at least 10.5%. This chromium plays a significant role in protecting the metal, as it reacts with oxygen in the environment to create a passive surface layer. This passive layer protects the metal from rust and encourages self-healing should small abrasions occur.
Steel and stainless steel have some notable differences in properties. Steel has magnetic properties and is classified into three general types based on its carbon content: high carbon, medium carbon, or low carbon. Steel has higher thermal conductivity, and therefore has better heat distribution.
Stainless steel is typically nonmagnetic, with some exceptions. Stainless steel has more hardening properties than steel, making it less malleable with lower thermal conductivity and heat distribution. Approximately sixty grades of stainless steel exist, and this is determined based on their degree of magnetism, chromium percentage, and the proportions of other elements.
A difference can be seen between steel and stainless steel finishes. When a lustrous shine is desired, stainless steel is the more luxurious metal with a natural sheen. The chromium coating provides stainless steel with this high-gloss look. Steel has a more matte finish with a slightly duller shine.
Powder coating options
Steel can be easily enhanced with some sanding and polishing, then topped with a clear coat or powder-coat paint for a refined finish. This coating elevates aesthetics and offers extra protection against the elements. Powder coating can be done in several colors and is used on both steel and stainless steel surfaces, though it is much more commonly done on steel. Powder coating not only protects the steel, but can add other advantages as well. Powder-coated site furnishings can be matched to the colors of nearby infrastructure or fit in with corporate color schemes. They can also be colored vibrantly, in opposition to the surroundings, to stand out and add visibility. This is critical for applications that rely on being noticed, such as safety equipment and safety bollards.
Both steel and stainless steel can be powder coated in various colors. Reliance Foundry’s R-7842 bollards have been powder coated in gray to enhance and protect its finish.
MAINTENANCE AND SELF-HEALING PROPERTIES
Due to the passive layer mentioned earlier, stainless steel requires minimal maintenance. However, it’s not necessarily immune to discoloration—and stainless steel can rust. That said, it can endure more abuse for a longer time. It also has unique self-healing capabilities. The chromium inside stainless steel forms a self-healing layer of oxide that reacts with oxygen and water in the environment. This prevents rusting, even in wet environments. The higher the chromium content, the more protection against corrosion.
When it comes to maintenance, regular maintenance of steel, stainless steel, and powder-coated finishes is recommended. A soft nylon brush and mild soap can be used to remove any accumulated dirt.
Another factor in selecting steel or stainless steel may come down to price. Stainless steel is costlier due to the addition of various alloying elements. It offers the benefit of extra protection against corrosion, however, and may be a worthy investment depending on the environment. Of course, not all environments are the same, and corrosion may not be a defining factor for some applications. In most mild, outdoor climates, steel products will fare very well if it has a protective coating.
Being a practical, plentiful, and economic alloy, steel is a perfect fit for substantial projects. Steel is used abundantly to construct roads and railways, as well as other large infrastructure. Modern buildings, stadiums, and skyscrapers are often supported by steel skeletons. Concrete structures may be reinforced with steel. Steel is also used for smaller construction materials such as bolts, nails, and screws.
Stainless steel applications
Stainless steel is sought out for both its practical and aesthetic elements. Like steel, stainless steel can be used to support large infrastructure, however, it also offers ornamental attributes. Stainless steel fixtures and panels add sophisticated design value to any building. Bridges and sculptures may also be composed of stainless steel to benefit from the metal’s resilience against rain and snow. Stainless steel is prominent in the food and beverage industry as well. It can be easily cleaned and sterilized and does not affect the taste of food products.
Outdoor site furnishings such as stainless steel bollards can withstand abrasive climates over the long term.
Both steel and stainless steel bring value at different price points. They are tough, dependable alloys that fit industrial settings as well as contemporary infrastructure. Their natural silver hue is a popular finish, while powder coating offers an economical and versatile enhancement. Both coated steel and stainless steel have the capacity to last in outdoor environments, however, stainless steel is always best for long-term use in abrasive conditions.
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Company: Reliance Foundry Co. Ltd.