Super Duplex Stainless Steel Fasteners
The term super duplex stainless steel is used to refer to duplex stainless steel with a pitting resistance equivalent number (PREN) of more than 40. Common characteristics of super duplex stainless steels include:
Excellent resistance to stress corrosion cracking in chloride-containing environments.
High tensile and yield strength.
The alloy generally contains at least 25% chromium, 7% nickel, 3.6% molybdenum, and 0.2% nitrogen, but these values can vary depending on the specific grade.
Applications of Super Duplex Stainless Steel Fasteners
A Super Duplex is a high-alloy duplex stainless steel that blends the strength of ferritic and austenitic steel types. It is stronger than ferritic steel grades and provides greater corrosion resistance. Super duplex stainless steel is used for a variety of applications, including oil and gas pipelines, seawater heat exchangers, seawater handling equipment, desalination equipment, scrubber systems in power stations, process vessels containing aggressive media, and liquefied natural gas tanks.
Duplex stainless steel is a family of stainless steel with dual microstructures of austenite and ferrite. This microstructure provides duplex stainless steel with greater strength than austenitic stainless steel with similar corrosion resistance. Alloy 2205 duplex stainless steel (UNS S32205, 1.4462) has a minimum yield strength of 65ksi (450MPa) compared to just 25ksi (170MPa) for Alloy 316L (UNS S31603, 1.4404).
Duplex stainless steel fasteners are a type of stainless steel fasteners that are corrosion-resistant and fairly easy to manufacture. They combine the best attributes of both austenitic and ferritic stainless steel. These include resistance to cracking, high strength, and toughness.
Advantages of Super Duplex Stainless Steel Fasteners
Apart from the advantages mentioned above, they can also be strengthened through additional processing. For example, stainless steel fasteners made of Duplex stainless steel can be hardened, which increases yield stress and ultimate tensile strength and lowers elasticity.
Super Duplex Steel S32750 Fasteners, such as UNS S32750, offer a combination of high strength and excellent corrosion resistance. In particular, they are resistant to stress corrosion cracking in chloride-bearing environments such as brackish water and seawater.
The steel can be strengthened by cold forming, which can double its strength in some cases, but is only applicable to smaller diameter bars. The steel is found to have a low toughness under impact loads. If the component will be working under tension with limited impact loading, this is an acceptable characteristic.