For many years, the 300 series austenitic stainless steels have been the workhorse alloys for various corrosive applications for Valve Industries. For severe applications, the nickel-base alloys were the next step up in corrosion resistance. The cost differential, however, was great: four to five times or even more, depending on the alloy chosen. In recent years, duplex stainless have started to fill this void as a cost-effective alternatives.
Similar to the 300 series of austenitic stainless steels, duplex stainless steels are iron base alloys with significant additions of chromium, nickel, and molybdenum. To produce a duplex stainless, the alloy chemistry is adjusted so both ferrite and austenite are present in approximately equal amounts. Duplex stainless steels are becoming commonplace in all types of chemical and petrochemical and refining industries because of their advantages over the conventional austenitic grades (such as CF8,CF8M & others) in many applications.
Duplex stainless steels are often used where chlorides or sour gas are encountered. Industries experiencing such environments include pulp and paper, chemical, oil and gas, power, desalination,
and marine.
To read the full article by Pradip Goswami, P.Eng,IWE – Independent Welding & Metallurgical
Engineering Specialist & Consultant, please contact Sarah Bradley at s.bradley@kci-world.com.