Duplex Stainless Steels

Duplex stainless steels are accurately termed Duplex austenitic-ferritic stainless steels. This terminology is derived from the approximately equal amounts of ferrites and austenite’s in the metallurgical structure. These steels have high chromium contents (18% to 28%) with low amounts of nickel (4.5% to 8%) and most grades contain molybdenum in the range of 2.5% to 4%.

Duplex steels are commonly referred to as lean duplex, duplex or super duplex in type. Lean duplex is achieved with the substitution of manganese where nickel may have been used and super duplex have chromium levels of 25% or more.

Characteristics of Duplex steels:

  • Good weldability and formability.
  • Higher tensile and yield strengths compared to standard austenitic and ferritic grades.
  • Increased resistance to stress corrosion cracking but do not match that of ferritic grades.
  • Small nitrogen addition enhances both strength and pitting resistance.
  • Increased level of passivity.

Grade and typical applications:

S31803 – (2205) – Superior corrosion resistance to 316L used in heat exchangers, gas scrubbers, fans, chemical tanks, marine and refinery applications.

S32304 – (2304) – Similar corrosion resistance to 316L with higher yield strength used in marine, mining, construction, food and power industries.

S32750 – (2507) – Extremely high corrosion resistance in severe marine, chloride and acid environments.

  • Duplex Steels
  • Duplex Steels
  • Duplex Steels
  • Duplex Steels
Grade EN # AISI # UNS # EN Name
C225MN 1.4462 F51/F60 S31803/S32205 X2CRNIM0N22-5-3
V234N 1.4362 S32304 X2CRNIN23-4
V257MNC 1.4582 X4CRNIM0NB25-7
V2101MW 1.4162 S32101
*LDX2101® 1.4162 S32101

*Outokumpu registered trademark

Superduplex Stainless Steels

Characterised by higher contents of Cr, Mo, and N than standard duplex steels, resulting in increased corrosion resistance, these steels were developed for applications in aggressive chloride environments.

Grade EN # AISI # UNS # EN Name
V257M 1.4410 F53 S32750 X2CRNIM0N25-7-4
V257MWU 1.4501 F55 S32760 X2CRNIM0CUWN25-7-4

Stainless Steels for Hot Forging

Grade EN # AISI # UNS # EN Name BS #
AISLF 1.4301/1.4307/1.4314 304/304L S30400/S30403 X5CRNI18-10/X2CRNI18-9 304S15/304S31
AISLF1* 1.4301/1.4307 304/304L S30400/S30403 X5CRNI18-10/X2CRNI18-9
AISTF 1.4541 321 S32100 X6CRNITI18-10
AISTF1* 1.4541/1.4544/1.4878 321/321H S32100/S32109 X6CRNITI18-10/X8CRNITI18-10/X12CRNITI18-9
APMLF 1.4401/1.4404 316/316L S31600/S31603 X5CRNIM017-12-2/X2CRNIM017-12-2/X2CRNIM017-13-2
APMLF1* 1.4401/1.4404 316/316L S31600/S31603 X5CRNIM017-12-2/X2CRNIM017-12-2/X2CRNIM017-13-2
APMTF 1.4571 X6CRMIM0TI17-12-2
V174F 1.4542 630 S17400 X5CRNICUNB16-4
V174F/1* 1.4542 630 S17400 X5CRNICUNB16-4
VAL1F 1.4006 410 S41000 X12CR13

* for heavy forging parts.