Specifications

Alloy 255
1.4507
X2CrNiMoCuN 25-6-3
Z3 CNDU 25-07 Az
Norsok MDS D59
ASTM A276/A476
UNS S32550
ASME A182 F61

Ferralium 255 – FG46 Fastener Grade (UNS S32550)

Ferralium^® 255 – FG46 is a super duplex stainless steel which is supplied in the strain hardened condition (Condition S). It is optimised for fastener applications, matching the mechanical properties of the B7 grade alloy carbon steel which is most commonly used for high-pressure bolting applications.

As a variant of our unique Ferralium^® 255 – SD50 product, it is a 25% Cr alloy with significant additions of Cu, delivering excellent corrosion resistance in a variety of corrosive chemicals including sulphuric, nitric and phosphoric acid.

In seawater and other chloride containing environments it also provides outstanding long term resistance to pitting and crevice corrosion, with a critical pitting temperature exceeding 50°C.

The product retains its excellent ductility and impact strength at both ambient and sub-zero temperatures, despite the elevated strength levels. These are combined with a high resistance to abrasion, erosion and cavitation erosion.

Ferralium® 255-FG46 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.

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Specifications

Alloy 255
1.4507
X2CrNiMoCuN 25-6-3
Z3 CNDU 25-07 Az
Norsok MDS D59
ASTM A276/A476
UNS S32550
ASME A182 F61

View Data Tables For This Product

Data Tables

Chemical Composition:

	Cr	Ni	Mo	Co	Nb (+Ta)	Ti	V	W	Cu	C	Mn	N	Si	P	S	Fe	Al
Min	24.50	5.50	3.10						1.50		0.80	0.20
Max	26.50	6.50	3.80						2.00	0.025	1.20	0.25	0.70	0.025	0.005	Balance

Mechanical Properties:

	Bars up to and including 4.0” diameter or section
0.2% Proof Stress	720 N/mm²	104.4 ksi
Tensile Strength	860 N/mm²	124.7 ksi
Elongation, 5.65√S₀ and 4D	16%
Reduction of Area	50%
Hardness (Brinell)	220-335
Impact Strength (Room Temp)	80J	59 ft.lb
Impact Strength (-46degC)	45J av (35J min)	33 ft.lb av (25.8 ft.lb min)

Notes:

Testing shall be carried out in accordance with ASTM A370 or EN ISO 6892-1 (tensile), EN ISO 6506-1 (hardness)
Minimum properties quoted (tested at room temperature in a longitudinal direction)
Testing performed on each melt of material per heat treatment batch
ASTM G48A corrosion test (at 50°C) no pitting and < 0.8g/m² weight loss
Ferrite content 35-55%
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)	220
Specific Electrical Resistance, 20°C (µΩ-m)	0.8
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

Key Features:

High Strength – the minimum 0.2% Proof Stress of 720 N/mm2 to match B7 carbon steel
Ferralium® was originally developed in 1960’s, pioneering the addition of nitrogen, to create the first super duplex stainless steel
Throughout the 1990’s, further developments were completed to extend PREN > 40, and more recently to increase its mechanical properties
Outstanding resistance to pitting and crevice corrosion in seawater and other chloride containing environments
Excellent corrosion resistance in a wide variety of corrosive chemicals including sulphuric, phosphoric and nitric acids
Excellent ductility and impact strength at both ambient and sub-zero temperatures
High resistance to abrasion, erosion and cavitation erosion
Excellent resistance to stress corrosion cracking in chloride containing environments
High structural integrity, optimised phase balance and the absence of sigma and other deleterious phases

Applications:

Ferralium® 255 – FG46 has been optimised for fastener applications, complementing where Ferralium® 255 – SD50 is routinely used
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

Specifications

Ferralium 255 – FG46 Fastener Grade (UNS S32550)

Specifications

Data Tables

Chemical Composition:

Mechanical Properties:

Notes:

Physical Properties:

Product Features

Key Features:

Applications:

Langley Alloys