Ferralium 255 is a super duplex stainless steel in the Ferralium series. This is the first super duplex stainless steel. Developed by Langley Alloys to meet the needs of the oil, gas and chemical industries, Ferralium 255 offers higher strength than most other stainless steel varieties and corrosion-resistant alloys. It is resistant to chloride SCC, as well as crevice corrosion and pitting corrosion. Additionally, it has twice the yield strength of Alloy 20.

Ferralium? 255 is a 25 Cr alloy with significant additions of copper that provides excellent corrosion resistance in a variety of corrosive chemicals. This includes sulfuric acid, nitric acid and phosphoric acid. Ferralium 255 contains 2% copper, which is higher than other super duplex stainless steels. As a result, Ferralium 255 has better acid resistance than most other alloys.

It’s not just the oil, gas and chemical industries where Ferralium 255 is booming, however. Ferralium 255 also has excellent resistance to pitting and crevice corrosion in seawater and other chloride-rich environments, making it an excellent material for use in marine environments. There are several contributing factors to this resistance. The first of these is because the critical pitting temperature of Ferralium 255 exceeds 50°C. At the same time, Ferralium 255 offers excellent ductility and impact strength at both ambient and subzero temperatures. These, together with the high resistance to wear, erosion and cavitation, ensure excellent resistance.

Ferralium 255 is listed in NACE MR 01 75 for sour service. Ferralium 255-SD50 is ASME certified for pressure vessel applications and is highly tested using tests designed to guarantee that the trademarked product has high integrity, correct phase balance, and the absence of sigma and other harmful phases. Ferralium 255 is less susceptible to the formation of these harmful phases than other superduplex stainless steels.

Since originally developed and patented by Langley Alloys in the 1960s, Ferralium 255 has been used successfully in some of the most demanding applications around the world. With a yield strength of >85ksi, it remains the strongest super duplex steel among solid bars. It is also available in aged and fastener grade condition.

Ferralium 255 chemical composition:

Ferralium 255 mechanical properties:

Ferralium 255 notes:

Testing should be in accordance with ASTM A370 or EN ISO 6892-1 (tensile), EN ISO 6506-1 (hardness)

Minimum properties quoted (tested longitudinally at room temperature)

For each heat treatment batch Material melt tested

Hardness shall comply with NACE MR 1075 with a maximum HRC value of 28 (270HB)

ASTM G48A Corrosion Test (at 50°C) No pitting and