Drum It Up! Steel Drum Industry News, Trends, and Issues

The Five Families of Stainless Steel

June 28th, 2018 by Natalie Mueller

Filed under: Stainless Steel

At Skolnik we offer a host of steel containers — our stainless steel drums offer an ideal solution for products requiring the purity, compatibility and strength of stainless steel. But just like Skolnik offers different families of products, there are different families of stainless steel. Five to be exact: austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, duplex stainless steel and precipitation hardening stainless steel. The families are classified by their crystalline structure.

 

Austenitic stainless steel is the largest family. About two thirds of all stainless steel produced falls into this category. Their crystalline structure is achieved by alloying with sufficient nickel and/or manganese and nitrogen. These stainless steels maintain their microstructure at all temperatures so they can’t be hardenable by heat treatment, but can be strengthened by cold working to an extent.

Austenitic stainless steel is great for formability and weldability, they are also essentially non magnetic. They’re often used for tanks, containers, storage vessels, architecture and the like.

 

Ferritic stainless steel has a structure more similar to carbon steel, contains between 10.5% and 27% chromium with very little or no nickel. Due to the chromium structure, ferritic stainless steel also holds its structure at all temperatures and is not hardenable by heat treatment. However, they are magnetic and are problematic to weld.

Welding creates microstructural problems so ferritic stainless steel is not used in the construction of large, heavy walled vessels and tanks and structures.

 

Martensitic stainless steels form a family that can be heat treated to provide the adequate level of mechanical properties. Martensitic stainless steels are magnetic and are less corrosion resistant than ferritic and austenitic due to a lower chromium content.

However, their high carbon content enables them to be significantly hardened so they are commonly used for knives, razor blades, cutlery and tools.

Duplex stainless steel’s structure is a combination of that of austenite and ferrite, usually at a 50/50 or 40/60 mix. It’s characterized by high chromium and molybdenum with lower nickel contents. The mixed microstructure results in higher resistance to chloride stress corrosion.

Duplex stainless steel can be difficult to weld properly, but can sometimes be a cost-effective solution for chemical processing, transport and storage, and marine environments.

 

Precipitation hardening stainless steel has corrosion resistance comparable to austenitic varieties but can be hardened to even higher strengths than martensitic steel. Precipitation hardening stainless steel is often used for gears, valves and other engine components, nuclear waste casks, and other pieces in aerospace and other high-tech industries.

 

Beyond that, there are over 150 grades of stainless steel.

Skolnik stainless steel drums are available in a variety of gauges and sizes and are stainless types 304 and 316, both austenitic, and 409, a ferritic stainless steel. And our products are built thicker, heavier and stronger than industry standards require.

 

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