What is a Duplex?
When 316 grade is insufficient, Duplex and Super Duplex grades of stainless steel provide superior corrosion resistance.
Duplex Stainless Steel Fasteners (SAF 2205 or UNS S31803) or Super Duplex Stainless Steel Fasteners (SAF 2507 or UNS S32750) are Stainless Steel grades that are frequently required in the fight against corrosion when 316 grade is insufficient, such as when submerged in salt water. The resistance to pitting and crevice corrosion of Duplex stainless steel is far superior to that of 304 or 316-grade stainless steel. This, combined with its high mechanical strength and ductility, makes it an ideal material for a wide range of applications.
Duplex Stainless Steel Bolts and Fasteners (SAF 2205 or UNS S31803) or Super Duplex Stainless Steel ers (SAF 2507 or UNS S32750) are Stainless Steel grades that are frequently required in the fight against corrosion when 316 grade is insufficient, such as when submerged in salt water. The resistance to pitting and crevice corrosion of Duplex stainless steel is far superior to that of 304 or 316-grade stainless steel. This, combined with its high mechanical strength and ductility, makes it an ideal material for a wide range of applications.
Technologies for Duplex Manufacturing
Duplex fasteners are best made with forged heads and rolled threads, with the heating temperature carefully controlled during the forging process.
Duplex fasteners can be CNC machined from round or hex bars, but forged heads and rolled threads are preferred. Threads should be rolled rather than machined to achieve smoother, stronger threads than machined/CNC threads; this improves yield strength, surface finish, hardness, and wear resistance.
Temperature control is critical when Hot Forging the fastener head. When heating a Duplex, avoid spending too much time in the critical temperature zone because this encourages the formation of unwanted Nitrides and Carbides. It is critical to use digital control equipment to quickly heat through this temperature zone and automatically remove it from the heat source when the temperature is suitable for forging. Any Duplex item should then be laser marked to ensure the fastener's traceability throughout the supply chain. Test certificates should also be obtained at all times.
Comments