As a leading structural steel manufacturer and service provider, Thrive Metal is committed to educating our clients about the materials we work with. Today, Many of our clients have asked about the meaning behind the name “Duplex 2205.” Today, we’re diving into the world of Duplex 2205 stainless steel, a popular grade known for its excellent corrosion resistance and mechanical properties.

The “Duplex” Component:

“Duplex” is indeed a technical term in metallurgy. It refers to stainless steels with a two-phase microstructure, typically consisting of roughly equal parts austenite and ferrite. This unique structure gives duplex stainless steels their characteristic blend of strength and corrosion resistance.

The “2205” Component:

Contrary to what some might assume, the “2205” designation doesn’t come directly from ASTM standards. Instead, it’s an industry-wide shorthand that offers a quick insight into the alloy’s composition:

• “22” represents approximately 22% chromium content
• “05” indicates about 5% nickel content

This naming convention provides a simple way for industry professionals to quickly identify the material’s key alloying elements.

ASTM Standards and Duplex 2205:

While “2205” is widely recognized, ASTM standards actually use the Unified Numbering System (UNS) to officially identify this material. You’ll find Duplex 2205 listed as UNS S32205 or S31803 in ASTM documentation.

At Thrive Metal, we often use both designations in our technical documents for clarity, such as “Duplex 2205 (UNS S32205).”