Specifications

  • Ferralium 255 – SD50
  • Super Duplex 255
  • Alloy 255
  • 1.4507
  • X2 CrNiMoCuN 25-6-3
  • Z3 CNDU 25-07 Az
  • Norsok MDS D57
  • Uranus 52N+
  • ASTM A276/A476
  • UNS S32550
  • ASME A182 F61
  • UNS S32520
  • CD4MCuN (Cast grade)
View Data Tables For This Product

Ferralium 255 – SD50 (UNS S32550)

Ferralium 255 is a super duplex stainless steel in the Ferralium family. It was the first super duplex stainless steel. Developed by Langley Alloys to meet the needs of the oil, gas and chemical industries, Ferralium 255 achieves higher strengths than most other stainless steel varieties and corrosion-resistant alloys. It is resistant to chloride SCC, as well as crevice corrosion and pitting. Furthermore, it features double the yield strength of Alloy 20.

As a 25% Cr alloy, with significant additions of copper, Ferralium® 255 offers excellent corrosion resistance in a wide variety of corrosive chemicals. This includes sulphuric, nitric and phosphoric acid. Ferralium 255 contains 2% copper, which is more than other super duplex grades. As a result, Ferralium 255 features better resistance to acids than most other alloys. 

However, it is not only the oil, gas, and chemical industries where Ferralium 255 thrives. Ferralium 255 also provides outstanding resistance to pitting and crevice corrosion in seawater and other chloride-rich environments, making it an excellent material for use in marine environments. This resistance has several contributing factors. The first of these is because the Critical Pitting Temperature of Ferralium 255 exceeds 50°C. At the same time, Ferralium 255 features excellent ductility and impact strength at both ambient and sub-zero temperatures. These, combined with high resistance to abrasion, erosion and cavitation erosion, ensure outstanding resistance.

Ferralium 255 was listed in NACE MR 01 75 for sour service. Having gained ASME Approval for Pressure Vessel applications, Ferralium 255-SD50 was tested to the highest degree using tests designed to guarantee that the trade-marked product possesses high integrity, a correct phase balance, and the absence of sigma and other deleterious phases. Ferralium 255 is less sensitive to the formation of these deleterious phases than other super duplex stainless steels.

Since its original development and patent by Langley Alloys in the 1960s, Ferralium 255 has been used successfully in some of the most demanding applications worldwide. With a yield Strength >85ksi, it remains the highest strength super duplex grade available in a solid bar. It can also be offered in the Aged and Fastener Grade condition.

Ferralium 255-SD50 is available for immediate delivery in 40 different sizes, from 0.5” (12.7mm) to 14” (304.8mm) in diameter. Our efficient processing facilities can provide accurately cut pieces. Extra testing, inspection and processing are all available in-house.

Ferralium 255-SD50

Specifications

  • Ferralium 255 – SD50
  • Super Duplex 255
  • Alloy 255
  • 1.4507
  • X2 CrNiMoCuN 25-6-3
  • Z3 CNDU 25-07 Az
  • Norsok MDS D57
  • Uranus 52N+
  • ASTM A276/A476
  • UNS S32550
  • ASME A182 F61
  • UNS S32520
  • CD4MCuN (Cast grade)
View Data Tables For This Product

Data Tables

Chemical Composition:

CrNiMoCoNb (+Ta)TiVWCuCMnNSiPSFeAl
Min24.505.503.101.500.800.20
Max26.506.503.802.000.0251.200.250.700.0250.005Balance

Mechanical Properties:

Bars up to and including 4.0” (100mm) diameter or sectionBars greater than 4.0” (100mm) and up to 12.0” (300mm) diameter or sectionBars greater than 12.0” (300mm) diameter or section
0.2% Proof Stress586 N/mm285ksi586 N/mm285ksi570 N/mm283ksi
Tensile Strength790 N/mm2114.5ksi790 N/mm2114.5ksi760 N/mm2110ksi
Elongation, 5.65√S0 and 4D25%25%25%
Reduction of Area50%50%50%
Hardness (Brinell)220-270220-270220-270
Impact Strength (Room Temp)80J59 ft.lb80J59 ft.lb80J59 ft.lb
Impact Strength (-46degC)45J av (35J min)33 ft.lb av (25.8 ft.lb min)45J av (35J min)33 ft.lb av (25.8 ft.lb min)45J av (35J min)33 ft.lb av (25.8 ft.lb min)

Notes:

  1. Testing shall be carried out in accordance with ASTM A370 or EN ISO 6892-1 (tensile), EN ISO 6506-1 (hardness)
  2. Minimum properties quoted (tested at room temperature in a longitudinal direction)
  3. Testing performed on each melt of material per heat treatment batch
  4. Hardness shall be in accordance with NACE MR 1075 with a maximum HRC value of 28 (270HB)
  5. ASTM G48A corrosion test (at 50°C)  no pitting and < 0.8g/m2 weight loss
  6. Ferrite content   35-55%
  7. Microstructure certified free from grain boundary carbides, sigma, chi and laves phases

 

 

 

 

Physical Properties:

Density (Kg/m3)7810
Magnetic Permeability (20°C)33
Young’s Modulus (kN/mm2)199
Specific Electrical Resistance, 20°C (Ω-m)0.80 x 10-6
Mean coefficient of thermal expansion, 20-100°C (m/m/degC)11.1 x 10-6
Specific Heat, 20°C (J/kg.K)475
Thermal conductivity, 20°C (W/m.K)14.2
Fracture Toughness, KQ (MPa/m2)98

Product Features

Key Features

  • Originally developed in the 1960s, Ferralium 255 pioneered the addition of nitrogen to create the first super duplex stainless steel
  • Continuously developed through the 1990s to extend PREN > 40 and more recently to increase mechanical properties
  • First super duplex stainless steel to achieve 586N/mm2 as a minimum 0.2% Proof Stress, up to 12” (300mm) section sizes
  • Pitting Resistance Equivalent (PREN) >40, indicating outstanding resistance to pitting and crevice corrosion
  • Very low levels of sulphur minimise the likelihood of inclusions as sites for potential pitting corrosion
  • Higher copper content provides a self-healing effect at sites of pitting to inhibit further growth
  • Available as bars, plate, pipe and fittings with complementary weld wire
  • Particularly suitable for larger components as the formation of the sigma phase is much less likely than it is for other Super Duplex grades

Applications

  • Oil & Gas industry pumps, valves, wellheads and subsea equipment
  • Pollution control scrubbers, precipitators, fans and pumps
  • Marine propellers, shafts, rudders, seals, pumps, valves
  • Bolts and fasteners
  • Process industry equipment in sulphuric acid, nitric acid, phosphoric acid, PP / PVC/TiOx production, agrochemicals
  • Grain and vegetable processing plant, sugar cane centrifuges
  • Pulp and paper digester blow vales, feed valves, washers, black liquor heater tubes, bleaching components
  • Copper smelting fans, tuyere bars, wet scrubbers, leaching area precipitators
  • Water and sewage treatment, desalination, swimming pools
Datasheet SD Ferralium 255 SD50 Bar Brochure Ferralium 255 SD50 detailed product information (rev2) Brochure Ferralium 255 SD50 Machining Guidelines Brochure Ferralium 255 SD50 Welding Guidelines Brochure Ferralium 255, The reliable alloy choice for acid production processes
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