Uses of Different Types of Stainless Steel maigne|September 13, 2018

Uses of Different Types of Stainless Steel

What are the different types of stainless steel?

  1. Ferritic stainless steel
  2. Austenitic stainless steel
  3. Martensitic stainless steel
  4. Duplex stainless steel

 

There are many uses of stainless steel in the Philippines; from the most basic cooking utensils to vehicle parts, industrial machines, to more complex parts, stainless steel is almost always present.

Everyone that aims to be an expert in steel needs to also know the many different kinds and specifications of stainless steel to identify the exact material for its respective use – in this case, the different kinds of stainless steel.

 

 

Ferritic Stainless Steel

This type of stainless steel is magnetic and has high amounts of chromium and low carbon content. It most known for its very high resistance to corrosion and stress corrosion cracking. This kind of stainless steel is comprised of a body-centered cubic grain structure—which basically means that its crystal structure is comprised of a cubic atom cell with an atom in the center.

Its magnetic properties come from the grain structure which is typical of an alpha iron. Because of this, ferritic steels cannot be strengthened using heat treatment—however, they can be cold worked and softened by annealing.

When compared to other types of stainless steel, particularly the austenitic grade, ferritic steel has better engineering properties. It is, however, limited to thinner gauges because of some ferritic steel grades are prone to sensitization of the weld heat-affected zone and weld metal cracking.

The most common uses of ferritic stainless steel are the following:

  • As part of automotive exhaust system silencers, automotive tubing, and catalytic converter casings.
  • Interiors of appliances, particularly washing machine drums, kitchen sinks, dishwashers, and some cooking utensils
  • Water tanks, solar water heaters, and microwave oven elements

 

 

Austenitic Stainless Steel

Austenitic Stainless Steel

A non-magnetic stainless steel grade that contains high levels of chromium and nickel, as well as low levels of carbon, Austenitic stainless steel is considered to be the most widely used grade of stainless steel. It is defined by its face-centered cubic crystal structure which has one atom at each corner of the cube and one in the middle of each face. Because of this, this stainless steel is not heat treatable but can be cold worked to improve hardness, strength, and stress resistance. Austenitic stainless steel is known for its formability, superior seismic performance, and ease of repair.

Austenitic stainless steel has a variety of grades that make use of the addition of additional metals in order to improve certain characteristics. For example, molybdenum can be added to a grade 316 austenitic steel to improve corrosion resistance.

Due to the austenitic stainless steel being the most common type of stainless steel, it also has the most applications—some of which include:

  • Automobile parts
  • Food and beverage equipment,
  • Storage vessels and pipes for corrosive liquids
  • Industrial equipment
  • Different kinds of architecture
  • Dishwashers and washing machines

 

 

Martensitic Stainless Steel

Developed as a stainless steel that is resistant to corrosion while also possible to strengthen through heat treatment, martensitic stainless steels are basically alloys that are similar to carbon or low alloy steels with a structure to ferritic steels. It has a body-centered tetragonal crystal structure and is classified as a hard ferromagnetic group. It has incredibly good ductility and toughness which decreases as its overall strength increases.

The strength that it gets from heat treatment depends on the carbon content of the steels. Higher carbon content means higher potential strength and hardness and lower ductility and toughness.

Martensitic stainless steel, when compared to other types of stainless steel has a relatively low profile—and its good tensile strength in combination with moderate corrosion resistance and heat resistance makes it perfect for these kinds of applications:

  • Surgical equipment
  • Dental equipment
  • Wires, screws, springs, blades, and cutting tools
  • Hydroelectric engines,
  • Sporting equipment industry

 

 

Duplex Stainless Steel

Duplex Stainless Steel

The last type of stainless steel that will be talked about is the duplex stainless steel. It gets its name because of its composition, which is basically a mix of both ferritic and austenitic grains of stainless steel—roughly 50% of each. This combination creates some very beneficial properties which are why it is a very special kind of stainless steel.

This mix between austenitic and ferritic stainless still spawned a kind of steel that has tremendous properties as the two masks the weaknesses of each other. Duplex stainless steels are twice as strong as regular austenitic or ferritic stainless steels. They also have a significantly better toughness and ductility when compared with ferritic steels. They have very good stress corrosion cracking resistance as well as corrosion resistance.

Because of their chemical composition and many properties, it’s not surprising that duplex stainless steel is more typically used in places where the other types of stainless steel have a hard time adapting to—in particular, duplex steels are most often seen in use at the following:

  • Chemical processing, transport, and storage
  • Oil and gas exploration and offshore rigs
  • Oil and gas refining
  • Pollution control equipment
  • Pulp and paper manufacturing

 

 

Key Takeaway

Stainless steel in the Philippines will always be something that individuals will find themselves using one way or another. Be it as kitchenware or as part of industrial equipment, you will almost always have to deal with something made out of stainless steel.