ThePipingMart Blog Metals SMO 254 vs Duplex – What’s the Difference

SMO 254 vs Duplex – What’s the Difference

SMO 254 vs Duplex

Choosing the right type of stainless steel is crucial for the success of any project involving metal fabrication. With the numerous options available in the market, it can be a daunting task to make the right decision. This blog will compare two common types of stainless steel – SMO 254 and Duplex – and help you determine which is better suited for your specific application.

Difference Between SMO 254 and Duplex

SMO 254, or 6 Moly Stainless Steel, is a high-performance, super austenitic stainless steel with excellent corrosion resistance in harsh environments. It contains high levels of molybdenum, chromium, and nitrogen, making it resistant to pitting, crevice corrosion and stress corrosion cracking. On the other hand, Duplex stainless steel is a two-phase, ferritic-austenitic stainless steel with excellent strength and corrosion resistance. It has a higher resistance to stress corrosion cracking and fatigue than SMO.


SMO 254 is commonly used in harsh environments such as chemical processing, marine, and offshore oil and gas industries. It is also used in pulp and paper production, desalination plants, and pharmaceuticals. In contrast, Duplex stainless steel suits chemical processing, desalination, and oil and gas production industries. Its strength, durability, and corrosion resistance make it popular for structural applications such as bridges, tanks, and pipelines.


SMO 254 is a premium stainless steel due to its high molybdenum content, making it more expensive than Duplex. Its cost is approximately 50-100% higher than Duplex. However, due to its excellent corrosion resistance and long lifespan, it is often considered a cost-effective investment in the long run.


SMO 254 is difficult to machine due to its high levels of nickel and chromium. It requires specialized cutting tools and machinery to prevent the material from hardening or cracking. On the other hand, Duplex stainless steel has good machinability, making it easier and cheaper to fabricate.


SMO 254 has excellent weldability but requires specific welding techniques to avoid post-weld heat treatments. Duplex stainless steel has good weldability, but care must be taken to prevent a loss in toughness and corrosion resistance while welding.


In conclusion, choosing between SMO 254 and Duplex stainless steel depends on the specific requirements of your application. SMO 254 is an excellent choice if you need high-performance, robust steel that can withstand harsh environments. However, it comes at a premium price. On the other hand, Duplex stainless steel is a more affordable option that offers excellent corrosion resistance while being more easily machinable. Ultimately, consider the cost, strength, durability, and corrosion resistance required for your project to make the right choice.

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