Outokumpu's FDX™ duplex stainless steel grades are proving to be well suited to demanding applications such as pump casings, where formability is an important requirement alongside strength, corrosion resistance and durability.
Pump casings often have to function under harsh conditions in terms of pressure, temperature, wear and corrosion risks. Manufacturers have not earlier been able to take advantage of the desirable properties of duplex steel grades because of their limited formability.
"We realized that such customers need solutions that combine the formability of austenitic steel grades with the strength and durability of duplex grades," explains Ramin Moshfegh, Senior Specialist, Forming and Virtual Product Development at Outokumpu's Avesta Research Center.
Moshfegh is convinced that Outokumpu's FDX duplex grades now fit the bill, as test production runs conducted in collaboration with Danish pump makers Grundfos proved. These tests demonstrated the impressive formability of FDX for manufacturing pump casings on a commercial scale. "The tests we conducted together with Grundfos have successfully taken FDX out of the lab into the real world," says Moshfegh.
Strength and formability
"It's crucial for customers like Grundfos that the high strength and resistance to wear, fatigue and corrosion of FDX grades greatly increase the service life of their pumps, and reduce the need for maintenance," says Moshfegh. "This unique combination of properties is due to the favorable microstructure and chemical composition of FDX. Nobody else than Outokumpu produces comparable grades as a commercial product to the market."
Another benefit of the high strength material is the opportunity to downgauge dimensions and produce lightweight pumps that save on material and space. The lower proportions of nickel in the alloy mix also enhance the price stability of FDX grades.
"The development of FDX grades with such impressive combinations of properties gives our customers great opportunities to expand the utilization of favorable duplex grades into challenging new applications like pump casings," adds Moshfegh.