Steels are the one of the most important materials in engineering and manufacturing. In material market, there are other superior steels called as stainless steels. These sort of steels are very common in professional applications because its long lifespan. In this article, we will explain the difference of stainless steels from plain steels and the types of stainless steels avaliable in market.
What Is Stainless Steel?
The alloying element that gives stainless property to the steel is high compositions of Chromium. Chromium is added as alloying element to steel to make stainless steel around 18%. But with the increasing percentage of carbon inside steel prevents the stainless property because of the formation of chromium carbide inside the microstructure. Free chromium elements inside steel microstructure creates thin oxide layer to prevent stain formation on the surface of steel. But chromium carbide also decreases the free chromium inside stainless steel structure.
Stainless steels are more expensive from plain steels also.
What Are The Types Of Stainless Steels?
- Austenitic Stainless Steels: This kind of stainless steel is the most corrosion resistant ste-el that includes 18% of chromium and 8% nickel inside it. Austenitic steels also known as 18-8 steels in market. Austenitic steels are non-magnetic and very ductile. Austenitic stainless steels are generally used in machinery parts that need corrosion resistance and food and chemical processing units.
- Ferritic Stainless Steels: Includes 15-20% of chromium, low carbon and no nickel. Ferritic stainless steels are less ductile, magnetic and less corrosion resistant compared with austenitic steels. Ferritic stainless steels are generally used in kitchen tools and jet engine components.
- Martensitic Stainless Steels: Includes higher carbon compared with ferritic stainless steels. 18% of chromium and no nickel inside them. Martensitic stainless steels are more fatigue resistant, harder but has no ability of corrosion resistance like others.
- Precipitation Hardening Steels: Includes 17% of chromium, 7% of nickel and small amount of other alloying elements such as aluminum, titanium, molybdenum and copper. As you understand from its name, these stainless steels are precipitation hardened and precipitation hardening steels can preserve their properties at elevated temperatures. Because of this, precipitation hardening steels are generally used in aerospace applications.
- Duplex Stainless Steels: Has microstructure of both austenite and ferrite. Show corrosion resistance as austenitic steels and has very good resistance to crackings that occur because of corrosions. The general applications of duplex stainless steels are pumps, heat exchangers etc.
Types of stainless stells and explanation of stainless steels can be summarized like above. Do not forget to leave your comments and questions about stainless steels below!