Duplex Steel Pipes & Tubes

Duplex 2205 is a nitrogen enhanced duplex stainless steel that was developed to combat common corrosion problems encountered with the 300 series stainless steels. “Duplex” describes a family of stainless steels that are neither fully austenitic, like 304 stainless, nor purely ferritic, like 430 stainless. The structure of 2205 duplex stainless steel consists of austenite pools surrounded by a continuous ferrite phase. In the annealed condition, 2205 contains approximately 40-50% ferrite. Often referred to as the work horse grade, 2205 is the most widely used grade in the duplex family of stainless steels. The advantage of a duplex structure is that it combines the favorable qualities of a ferritic alloy (stress corrosion cracking resistance and high strength) with those of an austenitic alloy (ease of fabrication and corrosion resistance). Usage of 2205 Duplex stainless steel should be limited to temperatures below 600° F. Extended elevated temperature exposure can embrittle 2205 stainless.

Forms of Duplex 2205

Sheet, Plate, Bar, Pipe & Tube (welded & seamless), Fittings (i.e. flanges, slip-ons, blinds, weld-necks, lapjoints, long welding necks, socket welds, elbows, tees, stub-ends, returns, caps, crosses, reducers, and pipe nipples), Welding Wire and Welding Electrode

. Corrosion Resistance

2205 duplex stainless steel is a cost effective solution for many applications where the 300 series stainless steels are susceptible to chloride stress corrosion cracking. Stress corrosion cracking occurs when stainless steels are subjected to tensile stress, while in contact with solutions containing chlorides. Increasing temperatures also increase the susceptibility of stainless steels to stress corrosion cracking. The combination of chromium, molybdenum and nitrogen convey the good resistance of 2205 to chloride pitting and crevice corrosion. This resistance is extremely important for services such as marine environments, brackish water, bleaching operations, closed loop water systems and some food processing applications. The high chromium, molybdenum and nitrogen contents of 2205 provide corrosion resistance superior to common stainless steels, such as, 316L and 317L in most environments.

Applications for Duplex 2205


Standard for Duplex

Alloy Designation	UNS	BS	EN	Basic	DIN	JIS	Trade Name	ASTM
Alloy 2205	S31803		1.4462	22Cr-5Ni-3Mo-0.15N	X2CrNiMoN22-5-3	SUS329L3L (JIS G3463)	SAF 2205 22Cr
Alloy 2205	S32205		1.4462	22.5Cr-6Ni-3Mo-0.2N			SAF 2205 22Cr	A789