Stainless steel is one of the most widely used types of metal in the world. The steel is a very durable and low-maintenance material. It is also environmentally friendly as it is recyclable. Stainless steel is basically a type of alloy that is made with at least 10.5 percent of chromium. The chromium creates an invisible chromium oxide film over the steel that is corrosion resistant. Therefore the steel is known as stainless because it can resist rust and corrosion.
This type of steel is commonly used in a variety of applications such as: stainless steel tables, kitchenware, lab equipment, surgical products, tools, chemical processing equipment, automobiles, consumer goods, white goods, the shipping industry, skate blades, cutlery, building material, hunting equipment, and office equipment, etc. Stainless steel is a marketing name and it covers a broad range of steel products. There are many types of stainless steel products used in the industrial world such as stainless steel tanks and stainless steel tubing.
Stainless steel is available in various forms such as: ingots, tubes, wires, shapes, extruded products, hot and cold rolled sheets, billets, and rods, etc. Stainless steel is assigned various grades per the ASTM standards. They are classified by the: chemical composition, the carbon content and the percentage of various alloys, etc. Common designations such as: 201, 301, 304L, 309, 310, 316L, 317, 321, 347 are used when grading various types of stainless steel.
Stainless steel can be machined to close tolerances and it can also be hardened and ground for special applications. It has good corrosion and wear resistance properties, can take an excellent finish, and it can be coated or painted by using different processes. Stainless steel has magnetic properties and medium electrical conductivity.
There are five main types of stainless steel available, which are Ferritic, Martensitic, Austenitic, Duplex, and precipitation hardening.
- Ferritic stainless steels are usually the least expensive. However they don't have as wide an application range as the others.
- Martensitic stainless steels can be hardened by quenching and tempering. This type off steel is generally used for cutlery, general engineering, and aerospace. When the steel is hardened it may become brittle. Because of this the steel isn’t usually hardened too much and it isn’t generally used for construction purposes.
- Austenitic stainless steels are the most commonly used. This type of steel is the most corrosion resistant.
- Duplex stainless steels are a combination of ferritic and austenitic. These steels are mixed together to improve the strength and corrosion resistance.
- Precipitation hardening stainless steels can also be strengthened by heat treatment processes.