Overview of typical applications for stainless steels
Stainless steel is a versatile material. First used for cutlery it soon found its way into the chemical industry because of its corrosion resistant characteristics. Today corrosion resistance is still of great importance and slowly bust steadily the mechanical characteristics of the material are being recognised. It is material that keeps on finding its way into new applications on a close to daily bases. Below you will find a number of applications where stainless steel has proven itself through many years of reliable service .
Cutlery and kitchenware
The most well known application stainless steels is probably for cutlery and kitchenware. The finest cutlery uses specially produced 410 and 420 for the knives and grade 304 (18/8 stainless, 18% chromium 8% nickel) for the spoons and forks. The different grades used such as 410/420 can be hardened and tempered so that the knife blades will take a sharp edge, whereas the more ductile 18/8 stainless is easier to work and therefore more suitable for objects that have to undergo numerous shaping, buffing and grinding processes.
Chemical, processing and oil & gas industries
Probably the most demanding industries that use stainless steels are the chemical, processing and oil & gas industries have created a large market for stainless tanks, pipes, pumps and valves as well. One of the first major success stories for 304 stainless steel was the storage of dilute nitric acid as it could be used in thinner sections and was more robust than other materials. Special grades of stainless have been developed to have greater corrosion resistance at a broad range of different temperatures. These are used in desalination plants, sewage plants, offshore oilrigs, harbour supports and ships propellers.
Stainless steels and other corrosion resistant alloys are extensively used in the power generation industry to combat corrosion, particularly at elevated temperatures. In particular nickel alloys are used for high temperature strength and oxidation resistance in fossil fuelled power plants. Nickel alloys and other stainless steels are also extensively used in flue gas desulfarization units.
The nuclear power industry also uses large quantities of stainless, often specified with a low cobalt content, for both power generation and radiation containment. Special louvered ventilation shafts are made, which are designed to be used in emergencies to seal off plants for years if necessary. Steam and gas turbines use stainless because of its corrosion resisting and heat resisting qualities.
Also large amounts of stainless steel are used in food production and storage. The most commonly used grades are 304 and 316. In general, 304 is basically the workhorse grade while 316 is used in harsher environments. An important reason fur using stainless steels is not so much the corrosiveness of the food itself as well as the fact that the use of stainless allows for faster and more efficient cleaning. For example in ice cream production 316 is specified so that strong anti-bacteriological cleaning and rinsing systems can be used. One of the great advantages of stainless steel is that it imparts no taste to the food that it comes into contact with.
Architecture, building and construction
Architecture, building and construction is a growing market as many modern buildings use stainless steels for cladding, roofing and facades. Another thing is that the low maintenance cost and anti-vandal characteristics of stainless provides a growing market in public transport, ticket machines and street furniture. Stainless steels are used for construction purposes, as well. When reinforced concrete first started to be used it was considered that the carbon steel used would not rust, as cement, obviously derived from limestone, is alkaline. However, constantly using grit salt on bridges can change the pH to acidic thereby rusting the steel which expands and cracks the concrete. Stainless steel reinforcing bar, although initially expensive, is proving to have very good life cycle costing characteristics.
Especially clean melted stainless is used for medical implants and artificial hips. A great deal of medical equipment - such as orthopaedic beds, cabinets and examination machines - is made as standard from stainless because of its hygienic and easy-clean qualities. Pharmaceutical companies use stainless for pill funnels and hoppers and for piping creams and solutions.
Cars are making increasing use of stainless steel, primarily for exhaust systems (grade 409) and catalytic converters, but also for structural purposes. With greater attention being made to achieving low long term maintenance costs, less environmental impact and greater concern with life cycle costs, the market for stainless steel continues to improve.
In Stainless Steel World Magazine December 2014 we published an article written by Jan-Olof Nilsson about the history and applications of stainless steel and the impact it has in our world and industry.