Five categories of stainless steel
Austenitic stainless steel. These are the most commonly used types of stainless steel. Compared with other alloy steels, austenitic stainless steels tend to have a higher chromium content and therefore higher corrosion resistance. Another common feature of austenitic stainless steel alloys is that they tend to be non-magnetic.
Ferrite stainless steel. The second most common form of stainless steel after austenitic alloys. As the name suggests, ferritic stainless steel is magnetic. These alloys can be hardened by cold working. They also tend to be cheaper due to lower nickel content.
Martensitic stainless steel .The least common category of stainless steel alloys. They tend to have lower corrosion resistance than ferritic or austenitic alloys, but they have high hardness. Martensitic stainless steel alloys are often ideal for applications requiring extremely high tensile strength and impact resistance. When the application also requires corrosion resistance, these alloys can be used with protective polymer coatings.
Duplex (ferritic-austenitic) stainless steel. This kind of stainless steel is named "duplex stainless steel" because of its composition; It is made of half austenite and half delta ferrite. These stainless steels have better corrosion resistance, especially against chloride pitting, as well as higher tensile strength than standard austenitic stainless steels. Due to its physical properties and chemical resistance, duplex stainless steel is widely used in pipeline systems in the oil and gas industry or pipelines and pressure vessels in the petrochemical industry.
Precipitation hardened (PH) stainless steel. This type of stainless steel is made of durable, corrosion-resistant alloys with excellent strength. They are treated to yield strength three to four times that of standard austenitic stainless steel. They are most commonly used in the aerospace, nuclear, and oil and gas industries.
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