A790 / A790M ASTM Duplex Stainless Steel Pipe UNS S32750 S32205
S31803 6MM - 830MM OD
|Size Range||O.D.: Φ6--Φ530mm, W.T: 0.8mm--30mm|
|SCH 5,SCH 10,SCH 20,SCH 40,SCH 80,SCH 120,SCH 160,SCH XXS|
|Specification||ASTM A778,ASTM A790, A790, A789|
Duplex stainless steels are called “duplex” because they have a
two-phase microstructure consisting of grains of ferritic and
austenitic stainless steel.
Strength: Duplex stainless steels are about twice as strong as regular
austenitic or ferritic stainless steels.
Toughness and ductility: Duplex stainless steels have significantly better toughness and
ductility than ferritic grades; however, they do not reach the
excellent values of austenitic grades.
Corrosion resistance: As with all stainless steels, corrosion resistance depends mostly
on the composition of the stainless steel. For chloride pitting and
crevice corrosion resistance, their chromium, molybdenum and
nitrogen content are most important. Duplex stainless steel grades
have a range of corrosion resistance, similar to the range for
austenitic stainless steels
Stress corrosion cracking resistance: Duplex stainless steels show very good stress corrosion cracking
(SCC) resistance, a property they have “inherited” from the
ferritic side. SCC can be a problem under certain circumstances
(chlorides, humidity, elevated temperature) for standard
austenitics such as Types 304 and 316.
Cost: Duplex stainless steels have lower nickel and molybdenum contents
than their austenitic counterparts of similar corrosion resistance.
Due to the lower alloying content, duplex stainless steels can be
lower in cost, especially in times of high alloy surcharges.
Additionally, it may often be possible to reduce the section
thickness of duplex stainless steel, due to its increased yield
strength compared to austenitic stainless steel. The combination
can lead to significant cost and weight savings compared to a
solution in austenitic stainless steels.