Introduction
Duplex stainless steels are materials of choice among designers, due to its superior features such as good corrosion resistance, high mechanical strength and good weldability, which makes them ideal for a wide range of applications across many industries. The two main components of duplex stainless steels are the austenite and ferrite phases. The combination of these two phases, along with other alloying elements, gives the material its properties. The ratio of austenite to ferrite determines the properties of the material such as its hardness and strength. Depending on the content and combination of elements, duplex steels can be divided into three main categories – lean duplex, standard duplex and super duplex. Lean duplex is the most economical option of the three, as it contains only a small amount of alloying elements and is the least expensive. It has good corrosion resistance, but is not as strong as standard and super duplex grade steels.
Properties of Lean Duplex Steel
Duplex stainless steels in the lean grade are lower alloy grades with fewer chromium and molybdenum when compared to the standard or superduplex grades. The low alloying elements result in a lower cost and an improved resistance to localized corrosion in comparison to the standard or superduplex grades. The mechanical properties are generally lower than the other grade with a yield and ultimate tensile strength at around 280-520 MPa, but still offering good corrosion resistance. The corrosion resistance is due to the higher portion of austenite present, which is stabler than the ferrite phase. Lean duplex stainless steel is the most economical grade for many applications, and can be used in a variety of industries such as food and beverage, pharmaceutical, and marine.
Applications of Lean Duplex Steel
Lean duplex stainless steels are used in a variety of industries where cost is a critical factor and good corrosion resistance is required. They are used in the marine and shipbuilding industry, where they are used to fabricate pipework, equipment, and hydraulic systems. The low alloying elements also makes them suitable for food and beverage applications, due to their non-detrimental effect on the product being processed. As lean duplex steel are lower cost than the higher alloyed grades, they are also used in the petrochemical, aerospace, and other industrial applications.
Advantages of Lean Duplex Steel
Lean Duplex stainless steels offer a number of advantages over other grades. Its lower cost makes it a popular choice for many applications where cost is an issue. Its excellent resistance to corrosion makes it suitable for numerous industries such as food, beverage and marine where a good level of corrosion resistance is required. The lower alloy content also makes it less susceptible to forms of corrosion such as stress corrosion cracking and pitting, making it an ideal material for extreme conditions. Its good weldability is also beneficial as it allows for easy fabrication and installation, while its high strength also makes it suitable for heavy duty applications.
Conclusion
Lean duplex stainless steels have gained in popularity due to its good corrosion resistance, high mechanical strength and good weldability, along with its excellent cost-benefit ratio. These materials are used in a wide range of industries such as marine, food and beverage and petrochemical. Its low alloying elements also make it less susceptible to forms of corrosion such as stress corrosion cracking and pitting, as well as providing good weldability and high strength. Therefore, lean duplex stainless steels offer an excellent choice for many applications where cost and corrosion resistance are critical factors.
