What Is the Main Distinction Between Duplex Steel S32205 And S31803?

ByAshwin Nik
_UNS S32205 -min-c8f5892a

UNS S32205 is what kind of material is it?

UNS S32205 is a ferritic, austenitic stainless steel with 22% chromium, 3% molybdenum, and 5% to 6% nickel. It is the most common grade of duplex stainless steel and has twice the yield strength of standard austenitic stainless steel grades. It performs well in the majority of caustic environments, has a high resistance to pitting and crevice corrosion, and is weldable.
UNS S31803 is what kind of material is it?

UNS S31803 is a duplex ferritic-austenitic steel. This alloy contains approximately 40-50 percent ferrite when annealed. The duplex microstructure has a high strength of ferritic grades while retaining the austenitic grades’ corrosion resistance.

There is a significant difference between S31803 and S32205:

UNS S31803 and UNS S32205 have more similarities than differences in their alloying. To begin with, they are both made of stainless steel and have similar elemental compositions. Both UNS S31803 and S32205 are duplex 2205 members, which means they are nearly equal parts austenite and ferrite.

S32205 has slightly higher minimum requirements for chromium, molybdenum, and nitrogen, but it still falls within the S31803 chemical composition range. This grade was created to address the potential loss of corrosion resistance and toughness in the heat-affected zone (HAZ) of some S31803 welds. As a result, users are advised to specify the S32205 grade. If the use of S31803 is required due to its inclusion in the ASME standard, the user should insist that the chemical composition of all S31803 grades also meet the composition requirements of S32205 grades. This will aid in maintaining a consistent performance.

Both S32205 and S31803 have high strength, exceptional impact toughness, and stress corrosion resistance. Pitting and crevice corrosion resistance is superior to 316L or 317L austenitic stainless steel in almost all corrosive media. It also has higher thermal conductivity and lower thermal expansion than austenitic steel, as well as excellent corrosion and erosion fatigue properties.

They have a high thermal strength range of 950-1150*c, which is comparable to type 430. However, it shows a significant increase in strength below 900°C. When compared to type 304, cold workability should be approached with caution because proof stress is high and elongation is low.