At POSCO, we never stop innovating, looking for new methods and new materials that can improve people’s lives. By developing new types of steel, POSCO is creating new possibilities and expanding efficiencies for all types of construction and creation.
One of our most exciting new products is PossSD – which stands for Super Ductile Duplex, a kind of duplex stainless steel. Duplex steel combines two types of stainless steel – austenitic and ferritic – to maximize the strengths and minimize the weakness of each.
The idea has been around since the 1920s, but only recently has technology and knowhow reached the point to make this a practical commercial product. And now, POSCO’s PossSD is one of the most exciting types of duplex steel to hit the market.
Combining Two Steels to Create an Innovative Alternative
Austenitic and ferritic steels are both considered fairly easy to make and fabricate, but both also possess certain drawbacks. Austenitic steels make up about 70 percent of all stainless steel production. These are low-strength steels that have low resistance to stress corrosion cracking, plus their high nickel content can make them more expensive.
Ferritic steel, on the other hand, have stronger engineering properties, but less resistance to corrosion. They use less nickel than austenitic steel, so tend to be cheaper.
By combining those two types of steel together, however, duplex steel is tougher and more ductile than ferritic grades, and are about twice as strong as both types of steel. It is also cheaper, while possessing stronger corrosion resistance.
Taking Duplex Steel to a Higher Level
PossSD takes those advantages to the next level. It is a high-alloy steel that features high corrosion resistance in severe marine, chloride and acid environments. It also has very limited nickel content, so is cost competitive. And the strip-casting process lets POSCO make PossSD with a higher nitrogen content.
Higher chromium and nitrogen make PossSD strongly anti-corrosive, and its strength gives PossSD anti-dent properties. But at the same time, enhanced ductility and elongation make PossSD highly formable. It also has excellent anti-fatigue properties.
Because PossSD is ferritic and austenitic, it is also magnetic, and therefore is induction heatable and good for cookware.
The strength of PossSD allows products that use it to be thinner and safer. And its high corrosion and wear resistance mean it is very useful for hoppers and tanks. It is an excellent floor material for refrigerated containers, with higher wear resistance and lighter weight.
High-strength enhances its safety factors, making it a good choice for safety items like fire doors and emergency ladders.
PossSD is also a hygienic steel, so it is also appropriate for water distribution and piping. And its strength means water ring thickness can be reduced 20 percent.
Finally, PossSD is versatile, and with proper treatment it can be employed for a wide array of other uses, like curtain walls, the exterior parts of electric battery chargers and artworks.
Stronger, Lighter, Cheaper
The many advantages of PossSD led to this POSCO World Premium product winning a World Steel Association Steelie Award in 2015 for being the Innovation of the Year.
In short, POSCO’s PossSD is an excellent example of what POSCO’s World Premium steel can be. Stronger, lighter, cheaper than regular steel options, PossSD is a major step forward for stainless steel.
To learn more about PossSD, be sure to check out this video.