ASTM A815 S31803 Duplex Steel Butt Weld 90Deg Elbow Pipe Fitting B16.9

ASTM A815 S31803 Duplex Steel Butt Weld 90Deg Elbow Pipe Fitting B16.9

ASTM A815/A815M-2001 Standard for Malleable Ferritic, Ferritic Austenitic, and Martensitic Stainless Steel Pipe fittings
 

S31803 belongs to duplex stainless steel. 22% chromium duplex (austenitic/ferritic) steel (2205 type), with moderate to high strength and good resistance to common corrosion/stress, corrosion/cracking.

This alloy has the ability to withstand chloride environments and sulfide stress corrosion, and its strength is approximately twice that of standard austenitic stainless steel. When higher mechanical strength/lighter weight is required, this alloy can be successfully used as a substitute for 300 series austenitic stainless steel. F51 is easy to use with many standard arc welding equipment for welding, but it is not recommended for oxygen and ethylene block welding because there may be carbonization of the welding metal.

Chemical composition

Minimum mechanical performance value

What is duplex stainless steel?

First, let's get to know duplex stainless steel. Duplex Stainless Steel (Duplex Stainless Steel, referred to as DSS), refers to ferrite and austenite each accounted for about 50%, generally less phase content also needs to reach at least 30% of stainless steel. In the case of low C, the Cr content is 18% to 28%, and the Ni content is 3% to 10%. Some steels also contain Mo, Cu, Nb, Ti, N and other alloying elements. This kind of steel has the characteristics of austenitic and ferritic stainless steel, compared with ferritic, higher plasticity, toughness, no room temperature brittleness, intergranular corrosion resistance and welding performance are significantly improved, while also maintaining the ferritic stainless steel 475℃ brittleness and high thermal conductivity, with superplasticity and other characteristics. Compared with austenitic stainless steel, it has higher strength and higher resistance to intergranular corrosion and chloride stress corrosion. Duplex stainless steel has excellent pitting resistance and is also a nickel-free stainless steel.

The characteristics of duplex stainless steel include:

1. molybdenum containing duplex stainless steel has good resistance to chloride stress corrosion under low stress, compared with austenitic stainless steel, high strength and resistance to intergranular corrosion and chloride stress corrosion has been significantly improved.

2. duplex stainless steel has the characteristics of austenitic and ferritic stainless steel, compared with ferrite, plasticity, toughness is higher, with superplasticity and other characteristics.

3. Duplex stainless steel is neither prone to welding hot cracks like the welding heat affected zone of ferritic stainless steel, nor more sensitive to welding hot cracks like austenitic stainless steel.

4. duplex stainless steel and austenitic stainless steel corrosion resistance is equivalent, some duplex stainless steel (such as 25%Cr, especially nitrogen containing high chromium duplex stainless steel) corrosion resistance and crevice corrosion performance exceeds AISI 316L.

Duplex stainless steel with high strength, good impact toughness and good overall and local resistance to stress corrosion. Its yield strength is twice that of austenitic stainless steel, giving this alloy a performance advantage over ordinary stainless steels such as 304,316. Because of the obvious advantages in performance, the price of this duplex steel is generally higher than that of ordinary austenitic stainless steel. Therefore, when customers purchase products, they also need to choose according to the specific pipeline design requirements.