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Duplex/Super duplex stainless steel

Sunmire is the only stockholder in North America to carry a full inventory of 2507 duplex stainless steel sheets from 3/16 inch to 1-1/2 inch thick。2507 duplex alloy is more cost-effective than 904L, 6% mo super austenitic stainless steel。

3/16" 1/4" 5/16" 3/8" 1/2" 5/8" 3/4" 1" 1 1/4"
4.8mm 6.3mm 7.9mm 9.5mm 12.7mm 15.9mm 19mm 25.4mm 31.8mm
 
1 1/2" 1 5/8" 1 3/4" 2" 2 1/4" 2 1/2" 2 3/4" 3"
38.1mm 41.3mm 44.5mm 50.8mm 57.2mm 63.5mm 69.9mm 76.2mm

Alloy 2507 (UNS S32750) consists of 25% chromium, 4% molybdenum and 7% nickel。Its strength and corrosion resistance is strong, mainly used in chemical processing, petrochemical and subsea equipment。It has strong chloride corrosion resistance, high thermal conductivity and low coefficient of thermal expansion。High chromium, molybdenum and nitrogen content, it has high resistance to spot corrosion, gap corrosion and uniform corrosion。

General attributes

2507 is a super duplex stainless steel composed of 25% chromium,4% molybdenum and 7% nickel。Its strength and corrosion resistance is strong, mainly used in chemical processing, petrochemical and subsea equipment。It has strong chloride corrosion resistance, high thermal conductivity and low coefficient of thermal expansion。High chromium, molybdenum and nickel content make it have high resistance to spot corrosion, gap corrosion and uniform corrosion。

It also has high impact strength, and 2507 is not suitable for use at temperatures above 570°F, where its toughness decreases over a long period of time。


Application field

  • Oil and gas industry equipment
  • Offshore platforms, heat exchangers, underwater equipment, fire fighting equipment
  • Chemical processing industry, utensils and pipes
  • Desalination plants, high pressure RO plants and submarine pipelines
  • Mechanical parts (high strength, corrosion resistant parts)
  • Energy industry FGD system, industrial washing system, absorption tower

标准

ASTM/ASME .......... A240 - UNS S32750
EURONORM............ 1.4410 - X2 Cr Ni MoN 25.7.4
AFNOR.................... Z3 CN 25.06 Az

Corrosion resistance

Uniform corrosion
The high chromium and molybdenum content of 2507 makes it resistant to organic acids such as formic acid and acetic acid。2507 alloy also has strong corrosion resistance to inorganic acids, especially those containing chloride。

Compared with 904L,2507 was more resistant to dilute sulphuric acid mixed with chloride ions。904L is an austenitic alloy designed to resist corrosion by pure sulfuric acid。

Grade 316L is not suitable for use in hydrochloric acid and may be subject to local or overall corrosion。2507 can be used in dilute hydrochloric acid environment, has strong resistance to spot corrosion and gap corrosion。

Isocorrosion curve 0 in sulfuric acid containing 2000ppm chloride ion.1 mm/year

Isocorrosion curve 0 in hydrochloric acid.1 mm/year, dotted line represents boiling point。


Critical loss temperatures of various alloys in 1m NACI


Critical crack corrosion temperature of various alloys in 10% FeCl3

Intergranular corrosion
The low carbon content of 2507 greatly reduces the risk of carbide precipitation in the intergranular during heat treatment, so the alloy has a strong resistance to carbide-related intergranular corrosion。

Stress corrosion cracking
The dual phase structure of 2507 makes it resistant to stress corrosion cracking。Because of its high alloy content, 2507 has better corrosion resistance and strength than 2205。2507 is especially suitable for offshore oil and gas extraction equipment。

Pitting corrosion
There are many ways to test the pitting resistance of steel products in solutions containing chloride. The data above are based on an electrochemical technique referred to in ASTM G61。The critical pitting temperature of high performance stainless steel in 1M sodium chloride solution is specified。The results demonstrated the excellent pitting resistance of 2507。Each level of test data is indicated by dark gray color。

Gap corrosion
Cracks are almost inevitable in construction and other aspects, which make stainless steel more vulnerable to corrosion in the chloride environment。 2507 has a strong crack corrosion resistance。 The critical temperature for cracking resistance of 2507 and other high performance stainless steel products is shown in the figure above。

Isocorrosion curve 0 in sulfuric acid containing 2000ppm chloride ion.The isocorrosion curve of 1 mm/year in hydrochloric acid is 0.1 mm/year, dotted line represents boiling point。 Critical corrosion temperature of various alloys in 10% FeCl3 at 1m NACI

Chemical composition

Average value (weight %)

Carbon Chromium Nickel Molybdenum Nitrogen 其他
0.020 25 7 4.0 0.27 S=0.001
PREN = [Cr%] = 3.3 [Mo%] = 16 [N %] ≥ 40

Mechanical properties of

Mechanical and physical properties

2507 has high tensile strength, impact strength, low coefficient of thermal expansion and high thermal conductivity。These characteristics apply to many structural and mechanical parts。 The mechanical properties of 2507 at lower and higher temperatures are shown below。All experimental data are obtained by testing annealed and hardened samples。

2507 should not be exposed to temperatures higher than 570°F for long periods of time, which may weaken its toughness。The data in the following table are for forged products only and should not be taken as a maximum or minimum unless otherwise specified。

Mechanical properties

0.2% residual deformation yield strength, KSI 80 min.
Ultimate tensile strength, KSI 116 min.
1% residual deformation yield strength 0.2%, ksi 91 min.
Extend within 2 inches % 15 min.
Hardness, rockwell C 32 max
Impact energy, FT-LBS 74 min.

Low temperature impact characteristic

Temperature ° F RT 32 -4 -40
Ft-lbs 162 162 155 140
Temperature ° F -76 -112 -148 -320
Ft-lbs 110 44 30 7

High temperature tensile properties

Temperature ° F 68 212 302 392 482
0.2% residual yield strength, KSI 80 65 61 58 55
Ultimate tensile strength, KSI 116 101 98 95 94

Physical properties

Density: 7800 kg/m3 - 0.28 lb/in3

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

Resistivity

(mu _ cm)
Thermal
conductivity
(W.m-1.K-1)
Specific
heat
(J.kg-1.K-1
Young
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

加工

Hot forming

2507 hot forming shall be carried out in the temperature range 1875°F to 2250°F, immediately followed by solution annealing at a temperature not lower than 1925°F, followed by rapid water quenching。

Cold forming

Many commonly used stainless steel forming methods are applicable to 2507. This alloy has higher yield strength and lower ductility than austenitic grade stainless steel。Therefore, the processor thinks it is necessary to enhance the forming strength, increase the bending radius, but also consider the factor of rebound。Compared to the austenite grade, the drawing, stretch forming and other processes of 2507 are more difficult to operate。When the shape requires 10% or more cold deformation, solution annealing and quenching are recommended。

Heat treatment

Solution annealing and quenching should be carried out after hot forming or cold forming。The temperature of solution annealing shall not be lower than 1925°F and shall be immediately followed by air or water cooling quenching。After heat treatment, the product is pickled and rinsed to obtain the desired corrosion resistance。

焊接

2507 is weldable and can be welded by SMAW, GTAW, PAW, FCW, or SAW. When welding 2507, it is recommended to use 2507/P100 metal, which will form a suitable two-phase structure。

Do not preheat 2507 unless you want to prevent cold metal concentration. Intermediate welding temperatures should not exceed 300°F, otherwise welding integrity will be compromised. The roots should be shielded with argon or 90% N2/10% H2 purification gas to ensure maximum corrosion resistance.The latter works better.

If only one side is welded, it is not possible to clean it after welding. We recommend GTAW as the root pass,GIAW and PAW cannot proceed without filler metal unless it can be cleaned after welding。If the heating is 5-38 kJ/in.SMAW or GTAW should be used。Let's say the heat is 50 kilojoules per inch., should adopt SAW。

说明
2205 Code Plus Two is a registered trademark of AvestaPolarit, Inc。254 SMO and 654 SMO are registered trademarks of AvestaPolarit Stainless Steel Corporation。 2304 is a registered trademark of Sandvik AB。

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。