What is Stainless Steel?
In metallurgy, stainless steel is defined as an iron-carbon alloy containing a minimum of 10.5% chromium. The chromium element is the main component that protects the steel from rust, as seen in the figure below. It gets its name from the fact that these steels do not stain, corrode or rust like other steels.
This material is also called corrosion resistant steel, especially in the aviation industry, in its undetailed form with alloy type and quality. Today, it is very easy to reach stainless steels in many different and easily accessible qualities and surface properties that work without problems in the harsh environmental conditions in which the product is applied throughout its life. Even in our normal daily lives, we see that these products are used very widely, from cutlery to watches.
High oxidation resistance under normal room temperature and air conditions is achieved with a minimum of 13% (by weight) chromium content, and up to 30% in extremely harsh environments. When the chromium element in stainless steel is exposed to oxygen (referring to atmospheric oxygen), it immediately forms a chromium-oxide (Cr₂O₃) passive layer.
This layer is too thin to be seen with the naked eye and completely blocks water, oxygen, or any gas from penetrating the underlying metal (stainless steel), thus protecting it. In case this layer is torn, scratched, or damaged, it can regenerate itself very quickly.
This phenomenon is called passivation, and it also occurs in other metals such as titanium. Stainless steel has a high resistance to corrosion and oxidation in many natural and man-made environments. However, selecting the right grade and type of stainless steel for each specific application is of great importance. The first step in grade selection is to analyze and define in detail all the existing and possible working conditions the stainless steel will be exposed to during the design phase. Elements like nickel—along with lower amounts of molybdenum and vanadium—also contribute to the passivation properties.
Thanks to its resistance to corrosion and staining, low maintenance cost, and visually appealing appearance, stainless steel is considered an ideal and indispensable material across a wide range of commercial applications. While there are over 150 stainless steel grades in total, 15 of them are widely used and well known in the market.
Similar to other types of steel, stainless steels are produced in various forms through hot and cold rolling processes, such as flat products, plates, rods, wires, tubes, long shaped products, and cast parts. They are widely used in the food industry, medicine, surgical equipment, industrial hardware, automotive, white goods, structural elements, and buildings, among many others.
One of the everyday uses of stainless steel is in jewelry and watches, which we often carry with us. The most commonly used grade in jewelry is 316L. Unlike silver, stainless steel does not oxidize or tarnish over time.
Additionally, its slightly lower density compared to silver makes it easier to work with in design. Stainless steel is 100% recyclable. About 60% of the stainless steel used in production is made from recycled materials such as scrap from end-of-life products and production waste.