Härtung von Duplex Edelstahl

Duplex stainless steels are a family of stainless steels. These are called duplex (or austenitic-ferritic) grades because their metallurgical structure consists of two phases, austenite (face-centered cubic lattice) and ferrite (body centered cubic lattice) in roughly equal proportions.

They provide better corrosion resistance, particularly chloride stress corrosion and chloride pitting corrosion, and higher strength than standard austenitic stainless steels such as A2/304 or A4/316. The main differences in composition, when compared with austenitic stainless steel is that duplex steels have a higher chromium content, 20–28%; higher molybdenum, up to 5%; lower nickel, up to 9% and 0.05–0.50% nitrogen. Both the low nickel content and the high strength (enabling thinner sections to be used) give significant cost benefits. Duplex steels also have higher strength. For example, a Type 304 stainless steel has a 0.2% proof strength in the region of 280 MPa (41 ksi), a 22%Cr duplex stainless steel a minimum 0.2% proof strength of some 450 MPa (65 ksi) and a superduplex grade a minimum of 550 MPa (80 ksi).[6]

Duplex steels are used extensively in the offshore oil and gas industry for pipework systems, manifolds, risers, etc. and in the petrochemical industry for pipelines and pressure vessels.

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The purpose of this process is to dissolve nitrogen in the surface of stainless steel to a depth of 1mm. Peak hardness ranges from 280HV on austenitic grades to 950HV on martensitic/ferritic grades.

The purpose of this process is to dissolve nitrogen and carbon in the surface of stainless steel to a depth in the range of 5-30µm. Peak hardness ranges from 1100-1300HV on all grades.

Expanite® surface hardening and heat treatment solutions unlock the full potential of duplex stainless steels by improving wear resistance, eliminating galling, and extending component lifetime without compromising corrosion resistance. With our proven expertise, we help customers in demanding industries achieve superior performance and reliability.

To gain a complete overview of how Expanite can support your material choices, we also invite you to explore our dedicated pages on Austenitic, Ferritic, and Martensitic stainless steels – and discover how our technology adds value across the full range of stainless steel alloys.