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Duplex/Super duplex stainless steel

Alloy 2304 (UNS S32304) is made of 23% chromium, 4% nickel, molybdenum free duplex stainless steel。The corrosion resistance of 2304 alloy is similar to that of 316L。In addition, its mechanical properties, i.e. yield strength, are twice as high as that of 304L/316L austenite。This feature allows designers to reduce the weight of products, especially pressure vessels。

3/16" 1/4" 5/16" 3/8" 1/2"
4.8mm 6.3mm 7.9mm 9.5mm 12.7mm
 
5/8" 3/4" 1" 1 1/4" 1 1/2"
15.9mm 19mm 25.4mm 31.8mm 38.1mm

Like the properties

2304 alloy is a duplex stainless steel composed of 23% chromium and 4% nickel。The corrosion resistance of 2304 alloy is similar to that of 316L。In addition, its mechanical properties, i.e. yield strength, are twice as high as that of 304L/316L austenite。This feature allows designers to reduce the weight of products, especially pressure vessels。

This alloy is particularly suitable for use in the -50°C /+300°C (-58°F/572°F) temperature range。It can also be used at lower temperatures under severe restrictions (especially for welded structures)。

Compared with 304 and 316 austenite, 2304 alloy has better stress corrosion resistance due to its dual phase microstructure, lower nickel content and higher chromium content。


应用

  • Most of the fields that 304 and 316 use
  • Pulp and paper industry (chip, chip storage tank, black or white liquid tank, classifier)
  • Caustic solutions, organic acids (SCC resistant)
  • The food industry
  • Pressure vessel (weight reduction)
  • Mining (abrasion/corrosion)

标准

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 2304 alloy itself has a high chromium content (23%), the corrosion resistance of 2304 alloy is almost the same as 316L。

Corrosion resistance in different organic acids

Corrosion resistance in static sulfuric acid (0,3 mm/year)

Local corrosion resistance
23% chromium and 0.The 1% nitrogen content makes 2304 duplex stainless steel more resistant to spot and gap corrosion than 316L。





Stress corrosion resistance
在氯化物浓度为(8ppm 02) PH =7, >1000 h的溶液里进行的抗应力腐蚀试验证明:由于2304较高的铬含量及较低的镍含量,2304比304L和316L具有更高的Stress corrosion resistance。

This is typical of duplex stainless steel, under the same conditions, 2205 alloy is superior to 2304 performance。



Other corrosion resistance
2304 alloy duplex stainless steel passes most of the standard IC tests, such as ASTM, A262E and C tests。It corrodes at a higher rate than 316L in 65% boiling nitric acid。Due to its high yield strength, this alloy is well suited to abrasion and corrosion environments。

Chemical composition analysis

100% weight

Carbon Chromium Nickel Molybdenum Nitrogen Others
0.020 23 4 0.2 0.1 S=0.001
PREN = [Cr%] = 3.3 [Mo%] = 16 [N%] ≥ 24

Mechanical properties of

Mechanical properties

°C Rp 0.2
MPa
Rp 1.0
MPa
Rp 1.0
MPa
°F YS 0.2%
Offset KSI
YS 0.1%
Offset KSI
UTS
KSI
Elongation
%
20 400 440 600 68 58 64 87 25
100 330 365 570 212 48 53 83 25
200 280 310 530 392 41 45 77 20
300 230 260 490 572 33 38 71 20

The above values are obtained in hot rolled plates (thickness ≤ 2 inches) and the °2304 alloy cannot be used for long periods at temperatures higher than 300°C (572°F)。Under such high temperature, precipitation and hardening are easy to occur。

Hardness (KTV minimum value)

温度 -50°C +20°C -60°F +70°F
A single numerical 75 J/cm_ 90 J/cm_ 54 ft. lbs 65 ft. lbs
The average value 90 J/cm_ 150 J/cm 65 ft. lbs 87 ft. lbs

硬度

Average (5) HV10 180-230 HB : 180-230 HRC _ 20

Physical properties of

Density: 7,800 kg/m3 - 0.28 lb/in3

Interval temperature
°C
Thermal expansion
ax10M-bK-1
°C

The resistivity

(mu _ cm)
Coefficient of thermal conductivity
(W.m-1.K-1)
Specific heat capacity
(J.kg-1.K-1
Young's modulus
E
(GPa)
Shear modulus
G
(GPa)
20-100 13 20 80 17 450 200 75
20-100 13 100 92 18 500 190 73
20-200 13.5 200 100 19 530 180 70
20-300 14 300 105 20 560 170 67

结构

The chemical composition analysis of 2304 is idealized as 50 α / 50 γ microstructure after solution annealing at 950°/1050°C (1742°/1922°F)。

The microstructure of 2304 is more stable than that of duplex stainless steel containing molybdenum。The intermetallic phase appeared after 10 hours of placement in the 750°/850°C (1382°/1562°F) temperature range。Copper in 2304 alloy increases the hardness of the steel after heat treatment in the 350°/500°C (662°/932°F) temperature range。

加工

Hot forming

Hot forming must be carried out in the temperature range of 1150/900°C (2100/1650°F)。After forming, it is recommended to perform solution annealing in the temperature range of 950°/1050°C (2100°/1650°F) to restore its corrosion resistance and mechanical properties。Care must be taken to avoid creep of the product during heating。

Cold forming

Cold forming of 2304 alloy is not difficult。304L and 316L cold forming equipment is also suitable for 2304。Due to its high mechanical properties, including yield strength, high pressure is required for cold forming。Finally, solution annealing is recommended to restore its mechanical properties and corrosion resistance, just like hot forming。

除锈

The solution and paste used are the same as 304L/316L。Due to its corrosion resistance, pickling time is slightly longer than austenite grade。

machinability

During drilling,2304 duplex stainless steel shows stronger machinability。Its performance is comparable to the 316LEZ*。In addition,2304 corrosion resistance and cleanliness is stronger。Local corrosion resistance has also been improved。

*316LEZ is a variant of 316L with improved machining performance



焊接

  • 2304 alloy can be welded with the following equipment:
    • TIG, manual and automatic
    • PLASMA, MIG, SMAW, SAW, FCAW
  • The duplex microstructure makes it insensitive to hot cracking。
  • Welding parameters must be optimized so that the ferrite content is controlled at 20-70%. We generally recommend heating at a maximum intermediate temperature of 150°C (302°F) of 10-25 KJ/cm for best results we must consider the thickness of the product and the welding equipment (consult necessary)。We do not recommend pre-weld or post-weld heat treatment. A full solution annealing treatment can be considered。

The technical information provided here reflects our best and most comprehensive knowledge at the time of compiling this information, but the content may change slightly as our research on corrosion grade products progresses。 We suggest you reconfirm the above information when you make an inquiry or place an order。In addition, every product has some special circumstances when it is used。The data provided herein are only descriptions of the products, which can only be regarded as our guarantee and commitment when our company makes written documents。