UNS Number S32550

Ferralium 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. 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.

Available Forms of Ferralium 255 at Rooplaxmi Steels:

•           Sheet
•           Plate
•           Bar

Characteristics of Ferralium 255:

•           Superior Corrosion Resistance
•           Pitting Resistance Equivalent (PREN) >40, indicating outstanding resistance to pitting and crevice corrosion
•           Chloride Stress Corrosion Cracking
•           General Corrosion In Many Environments
•           Good Ductility
•           High Strength-To-Weight Ratio
•           High Fatigue Strength In Marine Environments
•           Superior Abrasion and Cavitation Erosion Resistance
•           High Mechanical Strength - (over twice the yield strength of austenitic stainless steels)
•           Good Fabricability

 

Ferralium 255 Chemical Composition, %:

Cr	Ni	Mo	Cu	C	Mn	N	Si
24.5-26.5	5.5-6.5	3.1-3.8	1.5-2.0	0.025 max	0.8-1.2	0.20-0.25	0.70 max

P	S	Fe
0.025 max	0.005 max	Balance

 

Application of Ferralium 255:

•           Oil & Gas industry pumps, valves, wellhead 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

Machining and Fabrication with Ferralium 255:

Hot and cold forming can be performed on Ferralium F255 via traditional methods keeping in mind that the alloy is higher strength compared to 316 stainless steel. Hot working the alloy should be between the temperatures of 1800°F and 2100°F followed by an annealing heat treatment at 1950°F and water quench. Cold working the alloy to induce more than 10% deformation will require a similar heat treatment. For forming above 20% deformation, intermediate heat treatments should be performed.

Machining Ferralium F255 can be performed using the same methods as traditional stainless steels. Carbide tipped tools are preferred. Stress relieving by heating to 675°F briefly, followed by rapid cooling can be performed on heavily machined components. Welding can be performed by TIG, MIG or SMAW and should be performed on material in the annealed condition.

 

Ferralium 255 ASTM Specification:

Pipe Smls	Pipe Welded	Tube Smls	Tube Welded	Sheet / Plate	Bar
A790	A790	A789	A789	A240	A479

 

Mechanical Properties of Ferralium 255:
At Room Temperature

Ultimate Tensile Strength	110 ksi or 760 Mpa minimum
Yield	(0.2 % offset) 80 ksi or 550 Mpa minimum
Elongation	15 %