Stainless steel needs no introduction. It is something each of us has seen, touched and used. This versatile metal is popular and varied in its use-from cutlery and kitchen sinks, to high-precision machinery or surgical instruments. The composition of stainless steel can differ with the usage of alloys during the manufacturing process so as to produce different types of stainless steel to cater to a host of applications. Listed below are the most commonly used types of SS, and their uses:
- Austenitic stainless steel: Made up of 18% chromium and 8% nickel apart from some elements like nitrogen and manganese, this is the type of SS that finds the most widespread usage. Its malleability and high corrosion resistance are the attributes which make it account for a whopping 70% of all steel production. It performs equally well in both high as well as low temperatures. Applications for this type of steel include the production of very thin sheets and wires, chemical equipment, cooking utensils, kitchen sinks and food processing equipment. Superior quality austenitic stainless steel is used for manufacturing surgical instruments.
- Precipitation Hardening steel: The base metal for this kind is austenitic steel, which is then hardened by the addition of some elements. Typically composed of about 17% chromium and 4% nickel, this type of metal is remarkable in the way it can undergo shape alteration once heated to a sufficiently high temperature. Its extraordinary strength coupled with corrosion resistance makes it a very useful metal. It is mainly used in manufacturing shafts and pumps, turbine blades, aircraft parts as well as in equipment for the paper industry.
- Ferrite steel: Composed of little or no nickel and between 10.5to 27% chromium by weight, this type of SS is quite different from others in that it does not harden even after intense heating. Ferrite steel, in contrast to other types of SS is magnetic. It is also not as ductile as some of its peers. Its ability to guard against corrosion though is outstanding, even in seawater. Popular application for this type of stainless steel are in the manufacturing of car trim, exhaust systems, domestic appliances like boilers and washing machines, and cooking utensils.
- Martensitic steel: In a way, most of us know this type of steel rather well, since it is the one that is used for manufacturing household and commercial cutlery. High carbon content, between 0.1 and 1.2%, alongside 12-14% chromium, are the chief ingredients of Martensitic steel. Additional elements can include molybdenum and nickel. High temperature application results in hardening of this steel. Although lower than austenitic and ferrite, it also has considerable resistance to corrosion. Martensitic stainless steel is used for manufacturing spindles, pins, knife blades, fasteners, tools, valves, shafts. It also lends itself well in manufacturing surgical instruments due to its ability to be polished and impart sharp edges.
- Duplex stainless steel: This type is an amalgamation of the basic components of austenitic and ferrite steel in equal measures. With between 19% to 28% chromium, it offers the maximum resistance to corrosion, stress and overall damage amongst all the stainless steel types. It is also quite weld-able. It is used widely in manufacturing tools or machinery for marine, petrochemical, chemical and pulp industries.