Stainless steel is a type of alloy that is known for its exceptional corrosion resistance, strength, and versatility.  It is composed primarily of iron, along with varying amounts of chromium, nickel, molybdenum, and other elements, depending on the specific grade and composition.  The addition of these alloying elements imparts the unique properties that make stainless steel highly useful in a wide range of applications.

• See Article Link  -  AISI SAE Steel Numbering System

The key characteristic of stainless steel is its resistance to corrosion and staining, which is achieved through the formation of a thin, invisible layer of chromium oxide on the surface.  This layer, also known as the "passive layer," prevents oxygen and moisture from interacting with the underlying metal, thereby protecting it from rust and corrosion.  Stainless steel comes in numerous grades and types, each with specific properties that make them suitable for various applications. 

Some common types of stainless steel are

• Austenitic Stainless Steel  -  This type contains high levels of chromium and nickel, which make it non-magnetic and highly corrosion resistant.  It's often used in applications requiring good formability and weldability, such as kitchen appliances, food processing equipment, and chemical processing.
• Ferritic Stainless Steel  -  Ferritic stainless steel has a higher concentration of chromium and is known for its magnetic properties. It offers good resistance to corrosion but is not as resistant as austenitic grades.  It's commonly used in automotive exhaust systems and decorative applications.
• Martensitic Stainless Steel  -  Martensitic stainless steel is known for its high strength and hardness.  It can be heat-treated to achieve even greater hardness, making it suitable for applications like cutlery, surgical instruments, and turbine blades.
• Duplex Stainless Steel  -  Duplex grades have a balanced microstructure of austenite and ferrite, providing a combination of high strength and good corrosion resistance.  They are used in applications such as chemical processing, oil and gas equipment, and marine environments.
• Precipitation-Hardening Stainless Steel  -  These grades can be heat treated to achieve high strength and hardness.  They find use in aerospace components and high performance equipment.

Stainless steel's broad range of properties makes it suitable for various industries, including construction, architecture, automotive, aerospace, medical equipment, and more. Its durability, resistance to corrosion, and aesthetic appeal contribute to its widespread use in both functional and decorative applications.

Abbreviations

• SS - stainless steel
• ASS - austenitic stainless steel
• DSS - duplex stainless steel
• FSS - ferritic stainless steel
• MSS - martensitic stainless steel