High-performance SS steel challenges titanium on corrosion

Swedish stainless steel producer Outokumpu, has relaunched its high-performance stainless steel grade 654 SMO®. The grade, which offers superior corrosion resistance and mechanical properties, offers a cost-effective alternative for a host of applications where nickel alloys and titanium are presently employed.

The superaustenitic grade 654 SMO® provides a level of pitting and crevice corrosion resistance beyond that of other stainless steels. It is also nearly twice as strong as common austenitic stainless steels and is characterised by excellent ductility and toughness as well as good fabricability. 

The grade also offers a distinct cost advantage given that it contains significantly lower levels of costly nickel and molybdenum than common nickel alloys such as C-276. As such, it can be characterised as a “lean Ni-base alloy”.

Plate heat-exchanger manufacturers are a typical example of a customer group that can benefit greatly from 654 SMO®.

“By replacing nickel-base alloys they will reduce their financial risk since our champion will offer far better price stability,” says Mikael Willför, from Outokumpu‘s Technical Market Development Group, Avesta Research Centre. “Furthermore, they do not need to be dependent on the availability of titanium, which has fluctuated highly in the past. On top of this, 654 SMO® offers opportunities for down gauging when replacing titanium.”

Another interesting example is condenser tubing for nuclear power plants, where titanium can suffer so-called “droplet erosion.” The higher erosion resistance and superior stiffness of 654 SMO® can allow for thinner tubing walls and increased reliability over titanium. The grade has successfully replaced titanium in the most aggressive areas of Swedish and Finnish nuclear power plant condensers.

Other application areas where 654 SMO® can offer a distinct cost advantage include flowlines, seawater cooling systems, filters for off-gas handling as well as other flue-gas cleaning equipment.