Duplex stainless steels contain a mixture of austenite and ferrite in their structure, and exhibit characteristics of both phases with higher strength and ductility. Nitrogen is added to the second generation duplex alloys and provides strength and improved weldability.Type 2205 duplex stainless steel is a grade that offers very good pitting and uniform corrosion resistance, high strength and high resistance to stress corrosion cracking.
Typical applications for duplex alloys are heat exchangers, tubes, pipes, pressure vessels and tanks in the oil and gas and chemical processing industries.
Corrosion Resistance
The corrosion resistance of duplex stainless steels Type 2205 is superior to Types 304 and 316 stainless steels in many environments. Duplex stainless steels offer advantages in many applications due to their resistance to chloride stress-corrosion cracking (SCC) in addition to excellent pitting resistance.
Formability
Duplex stainless steels can be cold formed and expanded using a variety of forming operations. These steels have approximately two times the yield strength of austenitic grades and require greater loads during cold forming. Elongation, toughness and work hardening rates are lower than austenitic grades, but higher than those of ferritic grades.
Weldability
Duplex stainless steels can be readily welded by all fusion welding methods. The alloy should be welded without preheating, followed by cooling between each pass. A welding procedure should be developed so that a suitable ferrite-austenite balance is present in the weld fusion and heat affected zones of the final weldment.
