What is Stainless Steel?
Stainless steel is an alloy of Iron with a least of 10.5% Chromium. Chromium provides a thin sheet of oxide on the external surface of the steel known as the 'passive layer'. This avoids any supplementary corrosion of the surface. Increasing the amount of Chromium gives an improved resistance to corrosion. Stainless steel also comprises changing amounts of Carbon, Silicon, and Manganese. Other elements such as Nickel and Molybdenum may be added to convey other useful properties such as improved formability and better corrosion resistance.
What is Stainless Steel Used for?
Stainless steels of numerous kinds are used in thousands of presentations. The following gives a flavor of the full range:
Local – knives and forks, sinks, saucepans, washing machine containers, microwave oven liners, shaver blades
Architectural/Domestic Manufacturing – cladding, door and window fittings, street furniture, lighting columns, lintels, stonework supports
Transport – consume systems, car trim/grilles, road tankers, ship containers, ships chemical tankers, waste vehicles
Medical – Surgical instruments, surgical implants, MRI scanners.
Food and Drink – Catering equipment, preparing, distilling, food processing.
General – springs, fasteners (bolts, nuts, and washers), wire.
How Many Types of Stainless Steel are there?
It is generally divided into 5 parts:
Ferritic: These steels are created by Chromium with small quantities of Carbon generally less than 0.10%. These steels have the same microstructure to carbon and low alloy steels. They are commonly limited in use to comparatively thin sections due to lack of toughness in joins.
Austenitic: These steels are the most commonly used. Their microstructure is consequent from the addition of Nickel, Manganese, and Nitrogen. It is the same organization as happens in normal steels at much higher temperatures. This structure gives these steels their distinctive mixture of weldability and formability.
Martensitic: These steels are comparable to ferritic steels in presence created on Chromium but have higher Carbon levels up as high as 1%. This permits them to be toughened and strengthened much like carbon and low-alloy steels. They are used where high strength and reasonable corrosion resistance is essential.
Duplex: These steels have a microstructure which is nearly 50% ferritic and 50% austenitic. This gives them a higher asset than either ferritic or austenitic steel. They are resistant to pressure corrosion extremely. So-called “lean duplex” steels are conveyed to have comparable corrosion resistance to ordinary austenitic steels but with improved strength and resistance to stress corrosion furious.
Precipitation Hardening: These steels can improve very high strength by adding elements such as Copper, Niobium, and Aluminum to the steel. With an appropriate “aging” heat treatment, very fine components form in the matrix of the steel which imparts strength. These steels can be machined to fairly complex shapes requiring good acceptances before the final aging treatment as there is an insignificant alteration from the final treatment.
Amit Sanghvi is the writer of this article and Marketing Manager at Astec INC India. He is very familiar with varied types of stainless steels sheets and their properties, grades, and standards.