Stainless steel, duplex, UNS S32550, annealed

UNS S32550 Duplex Stainless Steel Designation

Wrought S-Steel: UNS S32550, annealed
UNS number	S32550
US name	ASTM A182 Grade F61
EN name	X2 CrNiMoCuN 25-6-3
EN number	1.4507

UNS S32550 Duplex Stainless Steel Composition detail

C (carbon)	0	–	0.04	%
Cr (chromium)	24	–	27	%
Cu (copper)	1.5	–	2.5	%
Fe (iron)	57.2	–	67	%
Mn (manganese)	0	–	1.5	%
Mo (molybdenum)	2.9	–	3.9	%
N (nitrogen)	0.1	–	0.25	%
Ni (nickel)	4.5	–	6.5	%
P (phosphorus)	0	–	0.04	%
S (sulfur)	0	–	0.03	%
Si (silicon)	0	–	1	%

UNS S32550 Duplex Stainless Steel Physical properties

Density

7.73

–

7.82

g/cm3

UNS S32550 Duplex Stainless Steel, Annealed, Mechanical properties

Young’s modulus	195	–	205	GPa
Specific stiffness	25.1	–	26.4	MN.m/kg
Yield strength (elastic limit)	520	–	580	MPa
Tensile strength	730	–	810	MPa
Specific strength	66.9	–	74.6	kN.m/kg
Elongation	23	–	27	% strain
Compressive strength	520	–	580	MPa
Flexural modulus	195	–	205	GPa
Flexural strength (modulus of rupture)	520	–	580	MPa
Shear modulus	75	–	81	GPa
Poisson’s ratio	0.3	–	0.32
Shape factor	43
Hardness – Vickers	250	–	280	HV
Hardness – Rockwell B	99	–	104	HRB
Hardness – Rockwell C	28			HRC
Hardness – Brinell	240	–	264	HB
Elastic stored energy (springs)	676	–	841	kJ/m3
Fatigue strength at 10^7 cycles	246	–	271	MPa
Fatigue strength model (stress range) Parameters: Stress Ratio = -1, Number of Cycles = 1e7cycles	231	–	289	MPa

UNS S32550 Duplex Stainless Steel, Annealed, Impact & fracture properties

Fracture toughness	192	–	212	MPa.m0.5
Toughness (G)	184	–	225	kJ/m2

UNS S32550 Duplex Stainless Steel, Annealed, Thermal properties

Melting point	1400	–	1450	°C
Maximum service temperature	335	–	365	°C
Minimum service temperature	-60	–	-50	°C
Thermal conductivity	13.3	–	17	W/m.°C
Specific heat capacity	450	–	481	J/kg.°C
Thermal expansion coefficient	12.1	–	14.5	µstrain/°C
Thermal shock resistance	186	–	231	°C
Thermal distortion resistance	0.978	–	1.32	MW/m
Latent heat of fusion	359	–	434	kJ/kg

UNS S32550 Duplex Stainless Steel, Annealed, Electrical properties

Electrical resistivity	83	–	87	µohm.cm
Electrical conductivity	1.98	–	2.08	%IACS
Galvanic potential	-0.24	–	-0.16	V

UNS S32550 Duplex Stainless Steel, Annealed, Magnetic properties

Magnetic type

Magnetic

UNS S32550 Duplex Stainless Steel, Annealed, Optical, aesthetic and acoustic properties

Transparency	Opaque
Acoustic velocity	5010	–	5140	m/s
Mechanical loss coefficient (tan delta)	6e-4	–	7.4e-4

UNS S32550 Duplex Stainless Steel, Annealed, Processing properties

Metal casting	Unsuitable
Metal cold forming	Limited use
Metal hot forming	Acceptable
Metal press forming	Limited use
Metal deep drawing	Limited use
Machining speed	16.5 m/min
Weldability Notes: Preheating and post weld heat treatments are not required	Good
Weldability – MIG	Excellent
Weldability – plasma	Excellent
Weldability – SAW	Excellent
Weldability – TIG	Excellent
Brazeability	Fair
Carbon equivalency	1.12 – 1.48

UNS S32550 Duplex Stainless Steel, Annealed, Durability

Water (fresh)	Excellent
Water (salt)	Excellent
Weak acids	Excellent
Strong acids	Acceptable
Weak alkalis	Excellent
Strong alkalis	Excellent
Organic solvents	Excellent
Oxidation at 500C	Excellent
UV radiation (sunlight)	Excellent
Galling resistance (adhesive wear) Notes: Aluminum bronze is the most suitable mating material to minimize galling.	Limited use
Flammability	Non-flammable

UNS S32550 Duplex Stainless Steel, Annealed, Corrosion resistance of metals

Pitting resistance equivalent number (PREN)	35.2 – 43.9
Pitting and crevice corrosion	Very high (>40)
Stress corrosion cracking Note: Rated in chloride; Other susceptible environments: Hydrogen sulfide	Susceptible
Intergranular (weld line) corrosion	Excellent
Inorganic acids	Good
Organic acids	Good
Alkalis	Good
Humidity / water	Excellent
Sea water	Excellent
Sour oil and gas	Good

UNS S32550 Duplex Stainless Steel Notes

This is a second generation of duplex.

UNS S32550 Duplex Stainless Steel Standards with similar compositions

International: X2CrNiMoCuN25-6-3 to ISO 16143-1, X2CrNiMoCuN25-6-3 to ISO 16143-2, X2CrNiMoCuN25-6-3 to ISO 9328-7

UK: X2CrNiMoCuN25-6-3 to BS EN 10216-5, X2CrNiMoCuN25-6-3 to BS EN 10250-4, X2CrNiMoCuN25-6-3 to BS EN 10272, X2CrNiMoCuN25-6-3 to BS EN 10297-2

USA: F61 to ASTM A182/A182M, S32550 to ASTM A240/A240M, S32550 to ASTM A276, S32550 to ASTM A473, S32550 to ASTM A479/A479M, S32550 to ASTM A789/A789M, S32550 to ASTM A790/A790M, S32550 to ASTM A815/A815M, S32550 to ASTM A949/A949M, S32550 to ASTM A959, S32550 to SAE J405, UNS S32550, UNS S39255, UNS S39553

Tradenames: FERRALIUM ALLOY NO. 255, FERRALIUM® 255-SD50, FERRINOX® 255