Delivery Time:10 DAYS
Certification:ISO9001:2008, PED 97/23/EC

UNS N08904 1.4539 Seamless Stainless Steel Tube Heat Exchanger Grade 904L

UNS N08904, commonly known as 904L, is a low carbon high alloy austenitic stainless steel which is widely used in applications where the corrosion properties of AISI 316L and AISI 317L are not adequate.

The addition of copper to this grade gives it corrosion resistant properties superior to the conventional chrome nickel stainless steels, in particular to sulphuric, phosphoric and acetic acids. However, there is limited use with hydrochloric acids. It also has a high resistance to pitting in chloride solutions, a high resistance to both crevice and stress corrosion cracking. Alloy 904L performs better than other austenitic stainless steels due to the higher alloying of nickel and molybdenum.

The grade is non-magnetic in all conditions and has excellent formability and weldability. The austenitic structure also gives this grade excellent toughness, even down to cryogenic temperatures.

The high chromium content promotes and maintains a passive film which protects the material in many corrosive environments.904L has a greater resistance to precipitation of ferrite and sigma phases on cooling and welding than other stainless steels containing molybdenum such as 316L and 317L. There is no risk of intercrystalline corrosion on cooling or welding due to the low carbon content. Its maximum service temperature is at 450°C.

  Applications:

Seawater cooling equipment

Chemical processing for sulphuric, phosphoric and acetic acids

Gas washing

Condenser tubes

Control and instrumentation

Heat exchangers

Production and transport of sulfuric acid Metal pickling in sulfuric acid Production and concentration of phosphoric acid Use in seawater, brackish water, condensers, heat exchangers and pipe work in general Paper and allied industries Gas washing Chemical and pharmaceutical industries   Specifications:

ASTM A213

ASTM A269

ASTM A312

BS EN 10216 pt.5

Mechanical Properties:

Temper	Annealed

Tensile Rm 71 ksi (min) Tensile Rm 490 MPa (min) R.p. 0.2% Yield 32 ksi (min) R.p. 0.2% Yield 220 MPa (min) Elongation (2” or 4D gl) 35 % (min)
Physical Properties (Room Temperature):

Specific Heat (0-100°C)	450	J.kg-1.°K-1
Thermal Conductivity	11.5	W.m -1.°K-1
Thermal Expansion	15.8	mm/m/°C
Modulus Elasticity	190	GPa
Electrical Resistivity	9.52	μohm/cm
Density	7.95	g/cm3

Chemical Composition (% by weight)

Element	Min	Max

C - 0.2 Mn - 2 Ni 23 28 Cr 19 23 S - 0.3 Mo 4 5 N - 0.1 Cu 1 2 P - 0.03 Si - 0.7