How is stainless steel made and what are its properties?

Stainless steel is made by combining iron with chromium and other elements, which gives it corrosion-resistant properties.

Stainless steel is an alloy, which means it is a mixture of metals. The primary component of stainless steel is iron, similar to other types of steel. However, what sets stainless steel apart is the addition of chromium. Typically, stainless steel contains a minimum of 10.5% chromium by mass. This chromium reacts with oxygen in the air to form a thin, invisible layer of chrome-containing oxide, known as the passive layer. This layer is self-repairing, even when scratched or damaged, and prevents further corrosion.

Other elements such as nickel, molybdenum, and nitrogen may also be added to enhance specific properties of the stainless steel. For example, nickel improves the formability and lustre of stainless steel, while molybdenum increases its corrosion resistance. The exact composition of stainless steel can vary depending on its intended use.

The process of making stainless steel involves melting the raw materials in an electric furnace. The molten metal is then cast into semi-finished forms. These forms are then heated and rolled into a variety of finishes and thicknesses, depending on the desired end product.

Stainless steel is renowned for its corrosion resistance. This is due to the chromium content which, when exposed to oxygen, forms a passive layer that protects the steel from corrosion. This makes it ideal for use in environments where corrosion is a concern, such as in the kitchen or in medical instruments.

In addition to its corrosion resistance, stainless steel also has high strength and durability. It is resistant to heat and fire, making it suitable for use in harsh environments. It is also easy to clean and maintain, which contributes to its widespread use in a variety of industries. Despite these advantages, stainless steel is more expensive than other types of steel, due to the cost of the alloying elements.