ThePipingMart Blog Metals Duplex Steel – Properties, Uses, Composition

Duplex Steel – Properties, Uses, Composition

Duplex Steel

Duplex steel is a type of stainless steel that has both ferritic and austenitic characteristics. This unique combination of properties makes it one of the most popular materials for engineers, as it offers superior strength, corrosion resistance, and durability compared to other types of stainless steel. In this article, we’ll take a look at the physical and mechanical properties of duplex steel, its composition, and some of its common uses.

Duplex Steel Physical Properties

One of the primary advantages of using duplex steel is its excellent physical properties. This includes higher strength than austenitic grades, good ductility and impact strength even at cryogenic temperatures, excellent resistance to stress corrosion cracking (SCC), and good fatigue strength. It also has high thermal expansion rates and low thermal conductivity. Additionally, duplex steel can resist localized corrosion, such as pitting and crevice corrosion, due to its high chromium content.

Duplex Steel Mechanical Properties

Duplex steel has impressive mechanical properties that make it suitable for a variety of applications. It has excellent tensile strength up to 1200 MPa (175 ksi) with good elongation values up to 30%. Its yield strength is generally twice that of conventional austenitic grades (up to 800 MPa/116 ksi). It also has very good fatigue strength even when exposed to cyclic loading or alternating stresses over long periods of time. Additionally, it exhibits very low thermal expansion rates and excellent creep resistance even at elevated temperatures up to 600°C (1112°F).

Duplex Steel Composition

Duplex steels are composed primarily of iron with alloying elements such as chromium (for improved corrosion resistance), molybdenum (for increased tensile strength) and nickel (for improved weldability).

Duplex Steel Uses

They are commonly used in industrial applications such as pump shafts, valves, piping systems, pressure vessels and heat exchangers. They are also widely used in marine engineering applications due to their superior corrosion resistance in comparison to other materials like carbon steel or aluminium alloys.


Duplex steels offer a unique combination of properties that make them ideal for use in many different industries where high-strength materials are needed, but weight must be kept low. Their combination of excellent tensile strength, fatigue resistance, ductility and corrosion resistance makes them invaluable for industrial applications such as pumps, shafts valves, piping systems, pressure vessels, heat exchangers, marine engineering components etc. With their ability to withstand extreme temperatures and pressures, they offer an advantage over other materials in these situations, making them a great choice for any industrial application requiring durable materials with superior performance characteristics.

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