{"id":8096,"date":"2026-05-19T11:45:29","date_gmt":"2026-05-19T09:45:29","guid":{"rendered":"https:\/\/gbcspa.com\/?p=8096"},"modified":"2026-05-19T12:07:26","modified_gmt":"2026-05-19T10:07:26","slug":"cutting-beveling-steel-duplex-super","status":"publish","type":"post","link":"https:\/\/gbcspa.com\/en\/cutting-beveling-steel-duplex-super\/","title":{"rendered":"Duplex and super duplex steel cutting and deboning: features, challenges and tools"},"content":{"rendered":"

Duplex and super-duplex steels combine austenitic and ferritic phases in similar proportions. This biphasic structure provides superior mechanical strength to standard austenitics and high resistance to chloride stress corrosion. Mechanical cold cutting is the recommended technology to preserve these properties: it requires carbide tools coated with specific geometries and a strict control of the process temperature.<\/em><\/p>\n

What are duplex and super duplex steels<\/h2>\n

Duplex stainless steels are named after the metallurgical structure: a biphasic matrix composed of austenitous ferritein in approximately<\/em> equal proportions<\/em> (40-60% each). This combination is achieved through precise chemical formulation and controlled heat treatment and underlies the properties that distinguish them from both standard austenitic steels and nickel superalloys.<\/p>\n

The most popular reference grade is duplex 2205<\/strong> (UNS S32205\/S31803): 22-23% chromium, 3-3.5% molybdenum, 4.5-6.5% nickel. The minimum tensile strength varies between 620 and 690 MPa depending on the semi-finished product (pipes or sheets\/bars), with a minimum yield strength of 450 MPa.<\/p>\n

The super duplex 2507<\/strong>(UNS S32750) takes features to a higher level: 25% chromium, 4% molybdenum, 6-8% nickel, with addition of nitrogen to stabilize the austenitic phase. The minimum tensile strength rises to 800 MPa, with a minimum yield strength of 550 MPa. The PREN (Pitting Resistance Equivalent Number) parameter, calculated with %Cr + 3,3x(%Mo + 0.5%W) + 16%N, reaches values above 40 (typically 42-45), compared to 34-36 for duplex 2205 and 22-26 for AISI 316L.<\/p>\n

Duplex, standard stainless steel and Inconel: three distinct families<\/h2>\n

Duplexes and super duplexes are iron-based<\/strong> steels<\/strong>, not nickel superalloys. The nickel content ranges between 4.5 and 8%, enough to stabilize the austenitic phase, but far from 50-72% of Inconel and Hastelloy. This distinction is essential to understand the positioning of these materials compared to other special alloys.<\/p>\n

Compared to AISI 316L, duplexes offer approximately double mechanical strength and superior resistance to chloride stress corrosion: the biphasic structure reduces susceptibility to pure austenitic SCC by combining the lower reactivity of the ferritic phase with the toughness of austenite. The price is higher than common stainless steels, but significantly lower than Inconel. Compared to the latter, the duplexes give way to high temperatures: maximum operating temperature in continuous between 250 and 280 degrees C. For nickel superalloys, refer to the article on cutting and blending of Inconel and nickel<\/u> superalloys on the blog GBC<\/a>.<\/p>\n

Where duplex and super duplex are used<\/h2>\n

The combination of high mechanical strength, chloride corrosion resistance and low cost compared to superalloys makes these materials ideal for critical industrial environments:<\/p>\n