{"id":492,"date":"2026-09-01T09:51:36","date_gmt":"2026-09-01T04:21:36","guid":{"rendered":"https:\/\/prestonalloys.com\/blog\/?p=492"},"modified":"2026-09-01T09:51:36","modified_gmt":"2026-09-01T04:21:36","slug":"s31803-vs-s32205-duplex-steel-plates-what-changes-in-mechanical-properties","status":"publish","type":"post","link":"https:\/\/prestonalloys.com\/blog\/s31803-vs-s32205-duplex-steel-plates-what-changes-in-mechanical-properties\/","title":{"rendered":"S31803 vs S32205 Duplex Steel Plates: What Changes in Mechanical Properties?"},"content":{"rendered":"

S31803<\/b> and <\/span>S32205<\/b> duplex steel plates combine mechanical strength that rivals many carbon steels with corrosion resistance close to austenitic stainless grades. Both belong to the duplex stainless steel family, and yet they are not identical. UNS S32205 carries a tighter chemical composition range than UNS S31803, and that difference shows up directly in pitting resistance, chloride tolerance, and consistency across a production batch. Choosing between them means understanding where these variations actually matter for design life.<\/span><\/p>\n

What Are S31803 and S32205 Duplex Steel Plates?<\/b><\/h2>\n

Duplex Steel S31803 Plates<\/b> and <\/span>Duplex Steel S32205 Plates<\/b> are flat-rolled products built on a two-phase microstructure holding roughly equal proportions of austenite and ferrite. This split delivers something single-phase stainless steel cannot: the ferrite phase raises yield strength and resistance to stress corrosion cracking, while the austenite phase supplies toughness and weldability. Refineries, offshore platforms, and chemical plants specify these plates wherever pressure ratings and chloride exposure drive material choice.<\/span><\/p>\n

S31803 vs S32205: What Are the Main Differences?<\/b><\/h2>\n

Mechanical minimums per ASTM A240 look nearly identical on paper. The gap opens once nitrogen, chromium, and molybdenum ranges are compared, and that gap decides real-world performance in <\/span>S31803 vs S32205 Duplex Steel Plates<\/b><\/a> selection.<\/span><\/p>\n\n\n\n\n\n\n\n\n\n\n\n
Property<\/b><\/td>\nS31803<\/b><\/td>\nS32205<\/b><\/td>\n<\/tr>\n
Yield strength (0.2% offset, min)<\/span><\/td>\n450 MPa (65 ksi)<\/span><\/td>\n450 MPa (65 ksi)<\/span><\/td>\n<\/tr>\n
Tensile strength (min)<\/span><\/td>\n620 MPa (90 ksi)<\/span><\/td>\n620 MPa (90 ksi)<\/span><\/td>\n<\/tr>\n
Hardness (max)<\/span><\/td>\n290 HB<\/span><\/td>\n290 HB<\/span><\/td>\n<\/tr>\n
Elongation (min)<\/span><\/td>\n25%<\/span><\/td>\n25%<\/span><\/td>\n<\/tr>\n
Toughness<\/span><\/td>\nReliable at ambient and moderately low temperatures<\/span><\/td>\nMore consistent batch-to-batch due to tighter nitrogen control<\/span><\/td>\n<\/tr>\n
Pitting resistance (PREN)<\/span><\/td>\n30 to 33<\/span><\/td>\n35 and above<\/span><\/td>\n<\/tr>\n
Chloride resistance<\/span><\/td>\nAdequate for moderate chloride service<\/span><\/td>\nHigher margin before pitting initiates<\/span><\/td>\n<\/tr>\n
Strength-to-weight ratio<\/span><\/td>\nRoughly double 316L on an equal yield basis<\/span><\/td>\nMarginally higher, driven by tighter alloy control<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

A plate schedule running near the pitting threshold on chloride or temperature gains a real safety margin from <\/span>S32205<\/b>, even though both grades share the same figures on a mill certificate.<\/span><\/p>\n

How Do S31803 and S32205 Behave in Corrosive Environments?<\/b><\/h2>\n

Both grades outperform standard austenitic stainless steel against chloride attack, but their margins separate once exposure turns severe.<\/span><\/p>\n