UNS S31803 and S32205 denote alloys with more similarities than differences. Firstly, they are both stainless steel with identical elemental components. Both S31803 and S32205 belong to the duplex 2205 family, which implies they comprise roughly equal proportions of austenite and ferrite. HT PIPE is a s31803 duplex stainless steel pipe supplier with 15+ export experience. Contact us for more information and quotes for free!
Everything you need to know about UNS S32205 and S31803
UNS S32205
Duplex UNS S32205 is a two-phase, ferritic, austenitic stainless steel alloyed with 22% chromium, 3% molybdenum, and 5 to 6% nickel. s32205 material is the most widely used grade of duplex stainless steel and is characterized by high yield strength, which doubles that of the standard austenitic stainless steel grades. s32205 stainless steel has high resistance to pitting and crevice corrosion and is excellent in most caustic environments. It also has good weldability.
S32205 duplex stainless steel Applications:
- Pulp Mills
- Food Processing
- Oil And Gas Piping
- Chemical Processing, and More.
Corrosion Resistance & PREN Values
The Pitting Resistance Equivalent Number (PREN) is the gold standard formula used by metallurgy engineers to estimate a stainless steel alloy's resistance to localized pitting in sour, chloride-heavy environments. The formula is calculated as:
UNS S31803 PREN Range: Typically spans from 31 to 38.
UNS S32205 PREN Range: Consistently delivers a higher threshold, typically ranging from 35 to 40.
Due to its elevated nitrogen and molybdenum minimums, S32205 duplex stainless steel provides superior protection against stress corrosion cracking (SCC), intergranular attack, and pitting in seawater, pulp mill bleaching systems, and petrochemical downhole piping.
Mechanical Properties & Industry Standards
Both alloys offer exceptional yield strength-nearly double that of conventional austenitic grades like 316L stainless steel. This allows design engineers to reduce wall thicknesses in pressure piping systems, lowering overall material weight and structural shipping costs.
Common Supply Standards:
Steel Plates, Sheets, and Strips: ASTM A240 / ASME SA240
Seamless and Welded Duplex Pipes: ASTM A790 / ASME SA790
Pipe Flanges and Forged Fittings: ASTM A182 / ASME SA182 (Grade F51 for S31803 / Grade F60 for S32205)
UNS S31803
S31803 material is a duplex grade with a ferritic-austenitic microstructure. This alloy s31803 consists of around 40–50% ferrite in the annealed condition. The Duplex 2205 / F51 duplex microstructure has the high strength of the ferritic grades while maintaining the corrosion resistance of the austenitic grades.
s31803 duplex stainless steel Application:
- Fuel Gas Filters
- Chemical Tanks
- Heat Exchangers
- Acetic Acid Distillation Elements
Why Choose Grade 2205 Duplex (UNS S32205)?
The initial specification of the duplex stainless steel was set as UNS S31803. But other manufacturers constantly produced this grade and upgraded it to the highest allowed specification. UNS S32205 contains higher nitrogen content which gives it extra strength. 2205 duplex stainless steel provides an additional protective cover against any corrosive compounds. UNS S32205's heightened corrosion resistance gives it a significant distinction from UNS S31803.
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