Stainless steel | Tuesday, 26 May 2015

How Many Types of Stainless Steel Are There?

The stainless steel industry is one of the biggest industries in the world. Stainless steel, as a material, has a number of different uses. Therefore it is only fair that the material has different variants of itself. Each type of stainless steel serves a different purpose and is used in a different way. The physical and chemical properties of these various types of stainless steel also differ from one another.

1. Ferritic

Based on chromium, these steels contain very small amounts of carbon, usually no more than 0.10%. The microstructure of these stainless steels resembles those of the carbon and the low alloy steels.

They are short in the strength department when it comes to welds, therefore their use is usually restricted to thin sections. In cases where welding is not a necessity, these steels can be used for a number of different applications. They also tend to be magnetic.

2. Austenitic

These are the most common types of stainless steel available in the market. Their microstructure is based on the addition of Nickel, Manganese, and Nitrogen.

The structure they have is similar to that of ordinary steel at high temperatures. They cannot be made tougher by applying heat. They are also prone to stress corrosion cracking. Generally, they are not magnetic but will display some minute magnetic properties depending on their composition.

3. Martensitic

There is a great deal of similarity between martensitic steels and ferritic steels since they are both based on Chromium. The difference lies in the carbon content, which can be up to 1% in martensitic steels. The high carbon content allows them to be hardened and tempered just like carbon steels.

In applications that require great strength and average corrosion resistance, martensitic steels are used. Martensitic steels are magnetic and usually have low weldability and formability.

4. Duplex

Duplex stainless steel has a mixed microstructure that consists of 50% ferritic and 50% austenitic stainless steel. Therefore, duplex stainless steels tend to be stronger than ferritic or austenitic steel.

Stress corrosion cracking is usually not a problem with duplex stainless steel. They have moderate weldability and formability. Their magnetic properties are not as high as that of the ferritic steels. There are basically two kinds of duplex stainless steel. One is called the “lean duplex” which has similar corrosion resistance to austenitic stainless steel. The other is the Super -duplex.

5. Precipitation Hardening (PH)

The addition of Copper, Niobium and Aluminum to these steels can greatly increase their strength. The strength is added as the aging heat treatment forms fine particles in the matrix of the steel.

These steels are also quite flexible as they can be machined into a number of different complex shapes. The corrosion resistance of these steels are similar to that of austenitic steels.

Use Cougartron to Clean All Types of Stainless Steel

With so much information being fed about stainless steels, it would be quite unreasonable to complete the detailed description on the subject without an insight into how stainless steels can be cleaned. Stainless steels can be cleaned during or after fabrication. Before stainless steel can be cleaned, one has to determine the substance that has to be removed. These range from shop oils (dirt, grease, grit and metal chips), to conversion oils (short time anneal oxides) to lubricant oxide mixtures (hot work scales).

Post-weld impurities can be particularly challenging to remove, regardless of the great anti-corrosive properties of stainless steel. Cougartron offers a wide selection of machines and accessories for effective cleaning and (re) passivation of stainless steel welds.

Our machines can successfully handle a wide range of applications, from occasional light-duty work to demanding tasks involving larger steel structures.