Alloy 825

Developed more than 70 years ago in Sweden for use in the sulfite paper industry, Duplex Stainless Steels now lead the way in creating advanced alloys for a wide range of commercial applications.

Originally created to combat corrosion problems caused by chloride-bearing cooling water and other aggressive chemical process fluids, Duplex stainless steels are now at the forefront of alloy technology thanks to their advanced complex microstructure, containing ferrite and austenite, and their unique chemical composition based on high volumes of Cr and Mo.  Coupled with additions of nitrogen, the net effect of this advanced construction formula is enhanced intergranular and pitting corrosion resistance.  In terms of yield strength and ultimate yield values, the overall results is an organically stronger steel with higher resistance to pitting and cracking from stress corrosion.

The best of both worlds

In many respects, Duplex Stainless Steels provide the best of both worlds -  proven ferratic stress corrosion cracking resistance coupled with the superior formability of the common austenitic stainless alloys – with the added bonus of delivering significant cost savings over high nickel alloys.

Since the 1970s, the second generation of Duplex stainless steels, with higher concentrations of nitrogen as an alloying agent, have led to this group of steels accounting for more than 80% of  duplex applications.

Four choices – endless applications

Today, modern duplex stainless steel can be divided into four groups:

• Lean Duplex such as 2304, which contains no deliberate Mo addition;
• 2205, the work-horse grade accounting for more than 80% of duplex usage
• 25 Cr Duplex such as Alloy 255 and DP-3
• Super Duplex, with 25-26 Cr and increased Mo and N compared with 25 Cr grades, including grades such as 2507, Zeron 100, UR 52N+, and DP-3W.