Ferralium® 255 – SD50 (super duplex 255) is a super duplex stainless steel supplied in the hot worked and annealed condition. It achieves higher strengths than most stainless steels and alternative corrosion resistant alloys, offering the potential to reduce section size and therefore weight and cost.
As a 25% Cr alloy, with significant additions of copper, Ferralium 255 offers excellent corrosion resistance in a wide variety of corrosive chemicals including sulphuric, nitric and phosphoric acid. Copper is widely known to improve resistance to acids, and Ferralium 255 contains 2% copper, which is more than other super duplex grades. In seawater and other chloride containing environments it also provides outstanding resistance to pitting and crevice corrosion, with Critical Pitting Temperature exceeding 50°C. Excellent ductility and impact strength at both ambient and sub-zero temperatures combine with a high resistance to abrasion, erosion and cavitation erosion.
Listed in NACE MR 01 75 for sour service and having gained ASME Approval for Pressure Vessel applications, Ferralium 255-SD50 is 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 1960’s, Ferralium 255 has been used successfully for more than 50 years in some of the most demanding applications worldwide. With a Yield Strength >85ksi it remains the highest strength super duplex grade available in solid bar and can also be offered in the Aged and Fastener Grade condition.
Ferralium is available for immediate delivery in 40 different sizes, from 0.5” (12.7mm) to 14” (304.8mm) diameter. Our efficient processing facilities can provide accurately cut pieces, with extra testing, inspection and processing all available in-house.
|Bars up to and including 4.0” (100mm) diameter or section||Bars greater than 4.0” (100mm) and up to 12.0” (300mm) diameter or section||Bars greater than 12.0” (300mm) diameter or section|
|0.2% Proof Stress||586 N/mm2||85ksi||586 N/mm2||85ksi||570 N/mm2||83ksi|
|Tensile Strength||790 N/mm2||114.5ksi||790 N/mm2||114.5ksi||760 N/mm2||110ksi|
|Elongation, 5.65√S0 and 4D||25%||25%||25%|
|Reduction of Area||50%||50%||50%|
|Impact Strength (Room Temp)||80J||59 ft.lb||80J||59 ft.lb||80J||59 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)|
|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|