What is Stainless Steel? Stainless steel is essentially a low carbon steel which contains chromium at 10% or more by weight. It is this addition of chromium that gives the steel its unique stainless, corrosion-resisting properties.
The chromium content of the steel allows the formation of a rough, adherent, invisible, corrosion-resisting chromium oxide film on the steel surface. If damaged mechanically or chemically, this film is self-healing, providing that oxygen, even in very small amounts, is present. The corrosion resistance and other useful properties of the steel are enhanced by increased chromium content and the addition of other elements such as molybdenum, nickel, and nitrogen.
There are more than 60 grades of stainless steel. However, the entire group can be divided into five families. Each is identified by the alloying elements which affect its microstructure and for which each is named.
Mainly because it was invented century ago, stainless has grown into a important material, its anti-corrosive qualities rendering it suitable for used in a huge range of different environments and circumstances.
Towards the lay person, one little bit of stainless steel may seem just like any other, however the truth of the matter is a bit more complicated. The sturdiness of metal cheap it doesn’t should be painted or coated in any way helps it be the optimal material to be used in places where cleanliness is definitely a high priority, for example hospitals or kitchens.
As mentioned previously, there is many form of stainless steel, with various grades being created via adding various other elements. They are selected to make slightly different alloys with particular properties including heat resistance or workability, which make the steel more suitable for specific tasks.
This versatility is reflected in the fact that there are actually over 150 different grades of metal, with fifteen ones to be the ones normally used. Popular grades of stainless steel include: 304 stainless steel and 316 stainless steel. With a simpler level, there are five types of stainless steel, which may be classified as follows:
Ferritic stainless steel – Ferritic stainless steels have ferrite (body centered cubic crystal) as their main phase. These stainless steels contain iron and chromium, based on the Type 430 composition of 17% chromium. Ferritic stainless steel is less ductile than austenitic stainless steel and is not hardenable by heat treatment.
Austenitic stainless steel – These are actually the most common types of stainless steel, accounting for 70% of all stainless production. Its versatility is mostly down to the fact that it is usually formed and welded with successful results.
Martensitic stainless steel – These types of steel shares some characteristics with ferritic, but boasts higher levels of carbon, up to a full 1%. This means that they can be tempered and hardened and are thus highly useful in situations where the strength of the steel is more important than its resistance to corrosion.
Duplex stainless steel – Put simply, Duplex stainless steels are a combination of ferritic and austenitic stainless steels, a structure which renders duplex stainless steel stronger than both.
Precipitation Hardening – With the addition of elements such as Aluminium, Copper and Niobium, these stainless steels become extremely strong. They can be machined and worked into a wide variety of shapes without becoming distorted and, in terms of corrosion, have the same resistance levels as austenitic stainless steels.