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Duplex 2304 Stainless Steel for Pipe and Tube

Penn Stainless inventory now includes Duplex 2304 (UNS S32304) in tubular products.

 

General Properties

Duplex 2304 is a 23% chromium, 4% nickel, molybdenum-free duplex (ferritic-austenitic) stainless steel. It has general corrosion resistance equal to or better than Alloys 304L and 316L, but with a higher yield strength–almost double that of austenitic stainless steels. Its duplex microstructure and low nickel and high chromium content also allows Duplex 2304 to demonstrate improved stress corrosion resistant properties compared to 304 and 316. It is usually suitable for all applications in the -58oF to 572oF (-50oC to 300oC) temperature range and posesses high mechanical strength, good weldability, good corrosion resistance, high resistance to stress corrosion cracking, good machinability, low thermal expansion, good fatigue properties, high thermal conductivity, and easy fabrication.

Specifications: UNS S32304

Applications:

Duplex 2304 is generally used in the same applications as Alloys 304 and 316L. Some examples include:

  • Chloride containing environments
  • Welded pipe systems within the Pulp and Paper, Chemical and Petrochemical, and Water Treatment industries
  • Transportations
  • Heat exchanger tubes
  • Architecture, building, construction
  • Pressure vessels
  • Caustic solutions, organic acids
  • Food industry

Standards:

  • ASTM/ASME: UNS S32304
  • EURONORM: FeMi35Cr20Cu4Mo2
  • DIN: 2.4660

Corrosion Resistance:

  • Due to its high chromium content–23%–the corrosion resistance properties of Duplex 2304 are almost exactly equivalent to those of Alloy 316L.
  • With a duplex microstructure and low nickel and high chromium contents, Duplex 2304 has improved stress corrosion resistance properties when compared to the 304L and 316L standard austenitic grades.
  • More resistant to pitting and crevice corrosion than Alloy 316L.
  • Outperforms Alloys 304L and 316L in stress corrosion cracking resistance when placed in chloride containing aqueous solutions.
  • Duplex 2304′s corrosion rate in boiling nitric acid–65%–is higher than that of Alloy 316L.
  • High yield strength allows Duplex 2304 to perform in abrasive/corrosive applications.

Structure

  • Microstructure of Duplex 2304 is more stable than duplex stainless steels that contain molybdenum
  • Duplex 2304 posesses almost exactly equal amounts of ferritic and austenitic in microstructure after annealing in a temperature about

 

 

Weldability

  • Can be welded by TIG manual and automatic, PLASMA, MIG, SMAW, SAW, FCAW
  • Duplex microstructure makes hot cracking less likely to occur.
  • Pre-heating and post welding not required
  • Filler metal should be balanced ferritic/austenitic

 Machinability

  • Possesses improved machinability properties, particularly when drilled
  • Low speeds and high feeds will minimize this alloy’s tendency to work harden

Composition

C

Cr

Fe

Mn

Si

S

P

Ni

Cu

N

Duplex

2304

0.03

max

min: 21.5

max:24.5

Bal.

2.5

max

1.0

max

0.03

max

0.04

max

min:3.0 max:3.5 min:0.05max: 2.0

min: 0.05

max: 2.0

Mechanical Properties

Grade

Tensile Strength ksi (MPa)

min

Yield Strength 0.2% offset ksi (MPa)

min

Elongation (% in 50mm) min

Hardness (Brinell)

MAX

Hardness

(Rockwell B)

MAX

Duplex 2304

87

(600)

58

(400)

25

293

31j

Physical Properties

Duplex 2304

Density at 68°F (20°C)

0.28 lbm/in3

7800 kg/cm3

Coefficient of Thermal Expansion

ax10-6°C-1

68°F to: 212°F

(20 -100°C)

13

68°F to 392°F

(20 -200°C)

13.5

68°F to 572°F

(20 -300°C)

14

Thermal Conductivity

W.m-1.K-1

at 68°F
(20°C)

17

at 212°F
(100°C)

18

at 392°F
(200°C)

19

at 572°F
(300°C)

20

Electrical Resitivity

(µ_ cm)

at 68°F
(20°C)

80

at 212°F
(100°C)

92

at 392°F
(200°C)

100

at 572°F
(300°C)

105

Specific Heat

(Btu/lb/°F)

32°F to: 212°F

(20 -100°C)

0.11

 

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