Composition of Stainless Steel

The composition for the different types of stainless steel is as follows:-

Stainless Steel Grades

Stainless steels are classified into four categories such as Ferritic, Martensitic, Duplex and Austenitic.

Ferritic Stainless Steel

This category inhibits carbon in the range 0.08-0.2 percent and 17 percent of chrome. The raise in chromium boosts corrosion resistance when heated at high temperatures. This type of stainless steel is magnetic.

• Type 430 – It contains low alloy ferritic steel and about 17 percent of chrome. It has excellent rust resistant properties of about 800 degrees Celsius. It is generally used in the sheet and strip form because of its reduced machinability.

Martensitic Stainless Steel

This category includes about 14 percent of carbon in the range of 0.08-2.0 percent and about 12 percent of chrome. Because of its elevated carbon content of the steel, it reacts to heat treatment to provide several mechanical powers like hardness. On heating, it illustrates useful grouping of mechanical properties and corrosion resistance which are helpful in a wide variety of purposes.

• Type 410 – This group contains the combination of 0.15 percent of carbon and 13 percent of chrome. It possesses good corrosion resistance and ductility. It can be simply machined and copied and displays excellent cold working properties.

• Type 416 – This type of grade is identical to Grade 410 and contains sulphur which provides improved machinability and is available in the bar form.

• Type 431 – The combination of this type of grade is 0.15 percent carbon, two and a half percent nickel and 17 percent chrome. This is generally available in the bar form.

Duplex Stainless Steel

This group includes the combination of nickel, chromium, nitrogen and molybdeneum to provide same alloy of ferrite and austenite. It is a highly rust resistant and high strength material. This can be heated at the temperature of -50-300 degree Celsius.

• UNS S32304 – The composition of this alloy mixture is 23 percent of chromium, 0.03 percent of carbon, 0.1 percent of nitrogen and 4 percent of nickel.

• UNS S31803 – This is the most largely used duplex grade and the composition is 22 percent of chromium, 0.15 percent of nitrogen and 0.03 percent of carbon.

Austenitic Stainless Steel

The composition of this group contains nickel in the range 8-20 percent and chromium in the range 17-25 percent. This type of steel is non magnetic.

• Type 316 – This group contains 12 percent of nickel and 2-3 percent of molybdenum which offers excellent corrosion resistance properties.

• Type 317 – This group contains the composition of 3-4 percent molybdenum which offers raised pitting resistance.