Austenitic and Duplex Stainless Steels

Austenitic stainless steels are widely used in the process industries because of their corrosion resistance, ductility and weldability. As corrosion processes become more aggressive it has been usual to switch from a low alloy, such as 304L or 316L, to other austenitic alloys with more molybdenum and, sometimes, nitrogen.

Austenitic alloys contain significant quantities of nickel and molybdenum, which are both expensive. There is now a full range of duplex stainless steels, with lower nickel and molybdenum contents, and, hence, a lower cost. A cost comparison in summer 2012 for hot rolled 10mm plate showed that if 316L is 1.0, 2101 duplex was 0.8. Similarly, 6%Mo austenitic was 3.1, while superduplex was 1.5.

For every austenitic stainless steel there is a duplex stainless steel with similar corrosion resistance and much higher strength, offering further potential cost savings. The modern duplex stainless steels are fully weldable with good toughness and ready availability in a wide range of product forms. Below are some common austenitic alloys with their duplex equivalents.

            AUSTENITIC                               DUPLEX
                 316L                                   2101/ 2003

            317L/ 904L                                  2205

                6%Mo                                   Z100/ 2507

Posted on: 7th Sept 2016

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Image (top left) by Agnieszka