Super duplex stainless steel is a high-performance alloy with superior corrosion resistance and strength compared to other stainless steel grades. It’s ideal for applications in industries where exposure to highly corrosive conditions, such as saltwater or chemicals, is common. But with so many different grades of super duplex stainless steel on the market, how do you know which is best for your application? Let’s take a closer look at the different grades of super duplex stainless steel and their properties.
Grade S32750 (2507)
UNS S32750 is a chromium, molybdenum, and nitrogen-alloyed austenitic-ferritic stainless steel. It has excellent corrosion resistance in a wide range of media and environments. Its pitting resistance equivalent number (PREN=Cr+3.3Mo+16N) ranges from 42–45, making it one of the most corrosion resistant grades available. Additionally, its yield strength can reach up to 80 ksi in annealed conditions—nearly twice that of type 316L stainless steel. It also has superior impact toughness at temperatures as low as -50°F (-46°C).
Grade S31803 (2205)
UNS S31803 is a nitrogen-alloyed austenitic-ferritic grade that offers outstanding corrosion resistance in many media and environments. Its PREN ranges from 35–37, and its yield strength can reach up to 70 ksi in annealed condition—twice that of type 316L stainless steel. It also has superior impact toughness at temperatures as low as -20°F (-29°C). The alloy features strong weldability, making it suitable for applications where welding might be necessary.
Grade S32304 (2304)
UNS S32304 is a nitrogen-alloyed austenitic-ferritic grade that offers good corrosion resistance in several media and environments. Its PREN ranges from 32–35, and its yield strength can reach up to 55 ksi in annealed conditions—more than twice that of type 316L stainless steel. It also has good impact toughness at temperatures down to -30°F (-34°C). This alloy has slightly lower weldability than other grades but remains suitable for welding applications where needed.
Conclusion
As you can see, various grades of super duplex stainless steel are available on the market today, each offering different levels of performance for various applications depending on your needs. Grade S32750 provides the highest level of performance with superior corrosion resistance, yield strength, and impact toughness. At the same time, Grade S32304 offers slightly lower performance levels with moderate corrosion resistance, yield strength, and impact toughness ratings. When selecting the right grade of super duplex stainless steel for your application, consider all factors before making your decision, such as environmental conditions, performance requirements, cost considerations, etc. With this information, you should be able to make the best selection possible for your project’s needs!
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