Duplex Stainless Steels

Duplex Stainless Steels

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 application:

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.

Stainless Steels for Hot Forging

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

* for heavy forging parts.

Grades

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

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