Duplex2507 stainless steel 1.44539（UNS32750）

What is Duplex2507 stainless steel?

Duplex 2507 (UNS S32750) is a super duplex stainless steel with 25% chromium, 4% molybdenum, and 7% nickel designed for demanding applications which require exceptional strength and corrosion resistance, such as chemical process, petrochemical, and seawater equipment. The steel has excellent resistance to chloride stress corrosion cracking, high thermal conductivity, and a low coefficient of thermal expansion. The high chromium, molybdenum, and nickel levels provide excellent resistance to pitting, crevice, and general corrosion.

Super Duplex 2507 stainless steel 1.44539 Products Form

• Flanges (Socket Weld, Weld Neck, Threaded, Blind, Orifice, Slip on, Lap Joint)
• Wire
• Bar
• Plate
• Fittings (returns, blinds, pipe nipples, pipe fittings, caps, tees, weld-necks, stub-ends, elbows, reducers, long welding necks, crosses, tube fittings)
• Sheet
• Pipe & Tube (welded & seamless)

Applications for Duplex2507 stainless steel

• Oil and gas industry equipment
• Offshore platforms, heat exchangers, process and service water systems, fire-fighting systems, injection and ballast water systems
• Chemical process industries, heat exchangers, vessels, and piping
• Desalination plants, high pressure RO-plant and seawater piping
• Mechanical and structural components, high strength, corrosion-resistant parts
• Power industry FGD systems, utility and industrial scrubber systems, absorber towers, ducting, and piping

Equivalents of grade 2507

EU TRONG	USA –	France AFNOR	Sweden SS
X2CrNiMoN25-7-4	S32750	Z3CND25-06Az	2328

Composition ranges for 2507 grade of stainless steel

1.4410 Super Duplex Chemical Composition
Grade	C	N	Mo	Cr	Ni
1.4410 (S32750 – F53)	%0.03 max	%0.24 – 0.32	%3 – 5	%24 – 26	%6 – 8

Mechanical Properties

Temper	Annealed
Tensile Rm	115	ksi (min)
Tensile Rm	800	MPa (min)
R.p. 0.2% Yield	80	ksi (min)
R.p. 0.2% Yield	550	MPa (min)
Elongation (2” or 4D gl)	15	% (min)

Physical Properties

Specific Heat (0-100°C)	500	J.kg-1.°K-1
Thermal Conductivity	15	W.m -1.°K-1
Thermal Expansion	11	mm/m/°C
Modulus Elasticity	200	GPa
Electrical Resistivity	8.12	μohm/cm
Density	7.8	g/cm3

Corrosion Resistance

32750 has excellent general corrosion resistance, superior to virtually all other stainless steels. It has

high resistance to intergranular corrosion and very high resistance to stress corrosion cracking in

both chloride and sulphide environments. It is the grade of choice for severe high temperature

marine environments and for chemical and petrochemical processing, even including some

solutions of strong acids.

Heat Treatment

2507 should be solution annealed and quenched after either hot or cold forming. Solution annealing should be done at a minimum of 1925°F. Annealing should be followed immediately by a rapid air or water quench. To obtain maximum corrosion resistance, heat treated products should be pickled and rinsed.

Hot working

2507 should be hot worked between 1875ºF and 2250ºF. This should be followed by a solution anneal at 1925ºF minimum and a rapid air or water quench.

Cold working

Most of the common stainless steel forming methods can be used for cold working 2507. The alloy has a higher yield strength and lower ductility than the austenitic steels so fabricators may find that higher forming forces, increased radius of bending, and increased allowance for springback are necessary. Deep drawing, stretch forming, and similar processes are more difficult to perform on 2507 than on an austenitic stainless steel. When forming requires more than 10% cold deformation, a solution anneal and quench are recommended.

Welding

2507 possesses good weldability and can be joined to itself or other materials by shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW), plasma arc welding (PAW), flux cored wire (FCW), or submerged arc welding (SAW). 2507/P100 filler metal is suggested when welding 2507 because it will produce the appropriate duplex weld structure.

Preheating of 2507 is not necessary except to prevent condensation on cold metal. The interpass weld temperature should not exceed 300°F or the weld integrity can be adversely affected. The root should be shielded with argon or 90% N2/10% H2 purging gas for maximum corrosion resistance. The latter provides better corrosion resistance.