ThePipingMart Blog Metals Difference Between Alloy 20 and Super Duplex Stainless Steel Alloys

Difference Between Alloy 20 and Super Duplex Stainless Steel Alloys

Alloy 20 and Super Duplex Stainless Steel Alloys

Two of the most popular choices for stainless steel alloys are alloy 20 and super duplex. Both of these alloys offer various advantages for different applications, but which one is best for your needs? Let’s take a look at how alloy 20 and super duplex compare.

Alloy 20

Alloy 20 is austenitic stainless steel that contains nickel, chromium, and molybdenum. It is known for its excellent corrosion resistance in various media, including acids such as sulfuric acid. This makes it ideal for chemical processing applications where corrosion resistance is key. Additionally, alloy 20 has good formability and weldability, making it easy to work with when fabricating parts or components.

Super Duplex Stainless Steel

Super duplex stainless steel is a combination of austenitic and ferritic steels that offers superior strength and corrosion resistance compared to other stainless steels. Its high chromium content gives it superior pitting resistance compared to standard 316 or 304 stainless steel alloys, making it ideal for use in highly corrosive environments such as marine or offshore applications. Additionally, the super duplex’s higher strength allows it to be used in applications with higher load requirements than what can be met by standard grades of stainless steel.

Cost Considerations

There are several factors to consider when considering the cost between alloy 20 and super duplex. Super duplex tended to be more expensive due to its higher chromium content and added strength than alloy 20; however, the increased cost may be offset by the fact that thinner gauges can be used due to the higher strength offered by super duplex over alloy 20. Ultimately, the cost difference between the two will depend on the specific application requirements.


When choosing between alloy 20 or super duplex stainless steel alloys for an application, several factors must be considered, including corrosion resistance requirements, fabrication capabilities, formability/weldability requirements, and overall budget constraints. Alloy 20 offers excellent corrosion resistance while being relatively easy to form/weld; however, if superior strength is needed or pitting resistance is necessary, a super duplex may be better suited for your application despite its higher initial cost. Ultimately deciding which material is best suited depends on each project’s unique requirements.

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