A Look at the Various Industrial Grades of Stainless Steel

Stainless is one of the most popular metals used in the construction numerous industrial equipment, and commercial products. While many think that stainless steel refers to just one metal, in reality, it refers an entire family of steel grades. These steel grades have different types under each of them. In this post, we take a look at the various stainless steel grades used by different industries.

Grades within the Stainless Steel Family

Stainless steel is differentiated in different grades by using various methods. However, the most common method is to differentiate them by the metallurgical structures. There are four grades of stainless steel:

  • Duplex: This grade comprises high levels of nickel (4-7%) and chromium (18-26%). The reason for the name duplex steel is that it contains a combination of ferrite and austenite. Duplex steel is created by combining these two compounds. Duplex steel provides benefits of high levels of corrosion resistance, and immense strength. They can also be welded easily. Duplex steel types include 2507, and 2205. 
  • Ferritic: The steels in this grade contain very little carbon, and are practically nickel free. However, they can contain up to 17% chromium. They are known for their immense resistance to corrosion and oxidation. They have adequate form-ability and weld-ability. Ferritic steel types include 405, 409, 430, 434, 436, 442, and 446. 
  • Austenitic: This is the most common grade of stainless steel used in different industries. Austenitic steel contain up to 12% of nickel, 26% of chromium, and small amounts of iron. These steels have better corrosion resistance than ferritic and martensitic steel grades. They have excellent form ability, and their deformation can be controlled using chemicals. They are extremely tough, especially at cryogenic temperatures. Other advantages include low thermal conductivity, excellent heat capacity, as well as thermal expansion. Types include 304, 317 (L, M, and MN), 321, and 347. 
  • Martenistic: This steel grade consist of small amounts of iron, 1.0% of carbon, and about 18% chromium. This material can be heat treated unlike ferritic and austenitic steel. These are ferromagnetic steels with harden ability, and moderate corrosion performance. However, they have low form ability capabilities, and can suffer from impact transition at low temperatures. Its types include 410, 410S, 414, 416, 420, 431, and 440.

By understanding the characteristics and types of each stainless steel grade, customers will be more informed about the stainless steel family. They will be able to make a better decision when choosing a stainless type or grade for manufacturing or production purposes.