The difference between duplex stainless steel and super duplex stainless steel

 When it comes to stainless steel, there are many options. One of the most popular options is duplex stainless steel. But what exactly is duplex stainless steel, and how is it different from super duplex stainless steel? Let's take a closer look.

What is duplex stainless steel?

Duplex stainless steel combines the properties of ferritic steel and austenitic steel to combine strength and corrosion resistance in a single material. It consists of two phases - ferrite (70%) and austenite (30%). The combination of these two phases provides high strength and excellent impact resistance, as well as a high level of corrosion resistance. This makes it ideal for chemical plants, desalination plants, Marine environments, wastewater treatment facilities, Bridges and other applications.

What is Super duplex stainless steel?

Super duplex stainless steel has all the same properties as regular duplex stainless steel, but has higher corrosion resistance due to its higher chromium content. This makes it a better choice for highly corrosive environments, such as offshore oil RIGS and other harsh environments exposed to seawater or acids. It also has a higher yield strength than normal duplex steel, so it can be used in applications where strength is prioritized, such as Bridges or heavy machinery parts.

Duplex stainless steel and super duplex stainless steel

The main difference between duplex stainless steel and super duplex stainless steel is their chromium and nitrogen content. Although the chromium content of both is similar, the nitrogen content of super duplex stainless steel is much higher, which helps it improve corrosion resistance than ordinary duplex steel. In addition, super duplex steel also has a higher yield strength, which makes it more suitable for applications where strength takes precedence over corrosion resistance.

works

Duplex stainless steel consists of austenitic and ferritic microstructures, while super duplex stainless steel contains additional austenitic microstructures. The composition of super duplex stainless steel is usually 25-27% chromium, 7-8% nickel, 3-5% molybdenum and 0.15-0.45% nitrogen.

strength

Duplex stainless steel is twice as strong as austenitic stainless steel, and super duplex stainless steel is even stronger. The extra strength of super duplex stainless steel makes it ideal for applications that require high strength and corrosion resistance, such as offshore oil and gas production.

Corrosion resistance

Duplex stainless steel and super duplex stainless steel have high corrosion resistance. However, super duplex stainless steels have better corrosion resistance due to the addition of austenitic microstructure. This microstructure has excellent resistance to pitting and crevice corrosion, making it ideal for use in corrosive environments.

cost

Duplex stainless steel is generally cheaper than super duplex stainless steel due to its lower nickel content. However, the cost difference between the two grades will vary depending on the specific alloy and supplier.

Application field

Duplex stainless steel is commonly used in a variety of industries, including chemical processing, oil and gas production, paper and seawater desalination. Super duplex stainless steel is often used in more demanding applications, such as offshore oil and gas production and seawater desalination.

Conclusion:

In conclusion, when deciding whether to use standard or super duplex stainless steel in your application, you should consider the importance of corrosion protection and strength to your project needs. If you need excellent corrosion protection, then super duplex steel may be the right choice, while if you need higher strength, then the standard grade may be the best for you. Whichever type you choose, be sure to talk to an experienced professional who can help guide you through the decision-making process so that your project is a success!