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Alloy 2304 UNS S32304 is a 23% chromium, 4% nickel, molybdenum-free duplex stainless steel. The Alloy 2304 has corrosion resistance properties similar to 316L. Furthermore, its mechanical properties, i.e., yield strength, are twice those of 304L/316L austenitic grades. This allows the designer to save weight, particularly for properly designed pressure vessel applications.

UNS S32304, is a lean duplex steel, similar to other duplex steels with it's high strength and resistance to chlorides stress corrosion cracking, however, due to its lower alloying content it has a lower level of pitting and crevice corrosion resistance (PREN approximately 26). As it contains very little Molybdenum, 2304 is a good economical alternative to 316L in some applications although 2304 is not recommended for use above 300°C. Also known by the the Uranus 35N and SAF2304.

The alloy is particularly suitable for applications covering the -50°C/+300°C (-58°F/572°F) temperature range. Lower temperatures may also be considered, but need some restrictions, particularly for welded structures. With its duplex microstructure, low nickel and high chromium contents, the alloy has improved stress corrosion resistance properties compared to 304 and 316 austenitic grades.

With its duplex microstructure and low nickel and high chromium contents, the alloy has improved stress corrosion resistance properties compared to 304 and 316 austenitic grades. Alloy 2304 duplex stainless steel successfully passes most of the standard IC test procedures such as ASTM, A262E, and C tests. Its corrosion rate in boiling nitric acid (65%) is higher than that of Alloy 316L. Due to its high yield strength, the alloy performs well in abrasion/corrosion applications.

Generally where 304 and 316L are used 
Pulp and paper industry (chip storage tanks, white and black liquor tanks, digestors) 
Caustic solutions, organic acids (SCC resistance) 
Food industry 
Pressure vessels (weight savings) 
Mining (abrasion/corrosion) 

ASTM/ASME.......... A240 - UNS S32304
EURONORM...........1.4362 - X2 Cr Ni 23.4
AFNOR...................Z3 CN 23.04 Az
DIN.........................W. Nr 1.4362

Corrosion Resistance
General Corrosion
Because of its high chromium content (23%) the corrosion resistance properties of 2304 are almost equivalent to those of 316L.

Localized Corrosion Resistance
The 23% chromium and 0.1% nitrogen additions explain why 2304 duplex stainless steel behaves much better than Alloy 316L when considering pitting and crevice corrosion resistance.

Stress Corrosion Resistance
Stress corrosion resistance test results in chloride containing aqueous solutions ((8ppm 02) PH =7, >1000 h, applied stresses higher than the yield strength) show that Alloy 2304 outperforms Alloys 304L and 316L, due to its high chromium additions and low nickel contents.

This is a typical feature of duplex stainless steels. Alloy 2205 performs still better than 2304 in similar conditions.

1.4362 Composition % according to EN-10216-5:

C Si Mn P S Cr Mo Ni N Cu
max. 0,03 max. 1,00 max. 2,00 max. 0,035 max. 0,015 22,00 - 24,00 0,10 - 0,60 3,50 - 5,50 0,05-0,20 0,10-0,60

S32304 Composition % according to ASTM A789,ASTM A790:

C Si Mn P S Cr Mo Ni N Cu
max. 0,03 max. 1,00 max. 250 max. 0,040 max. 0,040 21,50 - 24,50 0,50 - 0,60 3,00 - 5,50 0,05-0,20 0,50-0,60

Solution annealing : 950 - 1050 °C (water) 
Density 7800kg/m3
Hardness Brinell 290 Max
Tensile Strength @ Break 600 Mpa / 87000psi Min
Tensile Strength @ Yield 400 Mpa / 58000 psi 0.2% offsett
Elongation in 2" 25% Min
Modulus of Elasticity in tension 200Gpa 28500 ksi

General Properties
Resistance to Corrosion
Physical Properties
Mechanical Properties

ASTM A789/A789M
ASTM A 790/A 790M
Duplex Stainless Steel Pipe
Austenitic-Ferritic Stainless Steel Pipe
Super-Duplex Stainless Steels and their characteristics
2507 S32750(1.4410) Duplex Steel
S32205 S31803(1.4462) Duplex Steel
S32304(1.4362) Duplex Steel
Compared with the ferritic stainless steel, duplex stainless steel vulnerable
Compared with the austenitic stainless steel, duplex stainless steel strengths and vulnerable

Product Information for Lean Duplex 2304 tubing and pipe
Sizes Standard Tolerances
Products OD Wall Lengths and/or coils Grades OD Wall Lengths
Welded Heat Exchangers & Condensers

Specifications: ASTM-A789 and ASME-SA789

0.5" (12.7 mm) to 4" (101.6 mm)

Metric sizes available

0.020" (0.51 mm) to 0.150" (3.81 mm) Cut lengths to 60' (18.3 m) Lean Duplex 2304
<0.50" (12.7 mm)
+/-0.005" (0.13 mm)
0.50" (12.7 mm) to <1.50" (38.1 mm)
+/-0.005" (0.13 mm)
1.50" (38.1 mm) to <3.50" (88.9 mm)
+/-0.010" (0.25 mm)
>3.50" (88.9 mm) to 4.00" (101.6 mm)
+/-0.015" (0.38 mm)
+/-15% +/-10% +1/8"
(3 mm)

Physical Properties of Lean Duplex 2304 Alloys in the Annealed Condition at -20°F to +100°F

      Tensile Strength Yield Strength            
Alloy UNS Spec. psi MPa ksi psi MPa ksi Elongation in 2 in. (min.) % Grain Size Req. Max. Hardness Modulus of Elasticity (x106 psi) Mean Coefficient of Thermal Expansion (IN./IN./°F x 10-6) Thermal Conductivity (BTU-in/ ft2-h-°F)
Lean Duplex 2304

OD=1" & under

S32304 A789, A790 100,000 690 100* 65,000 450 58* 25 28 Rc, 30* Rc 27.5 7.6 180
Lean Duplex 2304


S32304 A789, A790 87,000 600 101* 58,000 400 58* 25 28 Rc, 30* Rc 27.5 7.6 180

*OD over 1.0"TS>87, YS>58, no hardness requirement 1.0" OD and under

Lean Duplex 2304 Product Range

UNS Designation
Werkstoff NR.
Lean Duplex 2304
A/SA789, A/SA790

*Note: The specifications noted including ASTM, ASME, or other applicable authorities are correct at the time of publication. Other specifications may apply for use of these materials in different applications

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