Datasheet updated

2024-01-11 10:30
(supersedes all previous editions)

Alleima® 2RK65 ('904L') is a high-alloy austenitic stainless steel intended for use under severe corrosion conditions within the process industry. The material is characterized by:

  • Very good resistance to attack in acidic environments, e.g. sulphuric, phosphoric and acetic acid
  • Very good resistance to pitting in neutral chloride-bearing solutions
  • Much better resistance to crevice corrosion than steels of the ASTM 304 and ASTM 316 types
  • Very good resistance to stress corrosion cracking
  • Good weldability

Standards

  • ASTM: '904L'
  • UNS: N08904
  • EN Number: 1.4539
  • EN Name: X1NiCrMoCu25-20-5
  • W.Nr.: 1.4539
  • DIN: X1 NiCrMoCu25 20 5
  • SS: 2562
  • AFNOR: Z2NCDU25-20
  • BS: 904S13

Product standards

EN 10088-3
Suitable for the production of flanges etc. according to ASTM A182 Grade F904L.

Certificates

Status according to EN 10 204 3.1

Chemical composition (nominal) %

C Si Mn P S Cr Ni Mo Others
≤0.020 0.4 1.8 ≤0.025 ≤0.015 19.5 24.5 4.1 Cu=1.5

Applications

Alleima® 2RK65 is a multi-purpose material for use under severe corrosion conditions. This has been proven both by laboratory tests and by extensive operational experience with the steel.

Typical applications for Alleima® 2RK65 are found in oil refineries and within the chemical and petrochemical industry.

Alleima® 2RK65 is also used within the pulp and paper, mineral and metallurgical and food industries, in seawater cooling and in many other fields.

The grade is an excellent alternative to standard austenitic stainless steels in heat exchangers using high temperature water with chloride contamination.

Industrial categories Typical applications
Chemical industry Flanges
Oil refineries Valves
Petrochemical industry Fittings
Pulp and paper industry Couplings
Food industry Rings
Mineral industry Seals
Metallurgical industry Bolts and nuts
Shafts
Forgings
Discs
Pigtails and headers

Corrosion resistance

General corrosion

Because of the high contents of nickel, chromium and molybdenum the resistance to general corrosion is above that of AISI 316L.

Pitting and crevice corrosion

The high chromium and molybdenum contents of this steel make its resistance to pitting and crevice corrosion superior to AISI 316L.

Stress corrosion cracking

Ordinary austenitic steels of the AISI 304 and AISI 316 types are susceptible to stress corrosion cracking in chloride-bearing solutions at temperatures above about 60°C (140oF). At high temperatures, above about 100oC, chloride contents as low as in the ppm-range (10-4 %) are sufficient to cause stress corrosion cracking in these steels. A nickel content of 25%, as is the case for 2RK65™, is sufficient to provide very good resistance under working conditions.

For further information regarding corrosion resistance of Alleima® 2RK65, please see the data sheet - Seamless tube and pipe - Alleima® 2RK65. The data should be considered in the knowledge that it may not be applicable for thick sections, such as forgings.

Forms of supply

Sizes and tolerances

Round-cornered square, as well as round billets, are produced in a wide range of sizes according to the following tables.
Larger sizes offered on request.

Surface conditions

Square billets

Unground, spot ground or fully ground condition.

Round billets

Peel turned or black condition.

Square billets
Size Tolerance Length
mm mm m
80 +/-2 4 - 6.3
100, 114, 126, 140, 150 +/-3 4 - 6.3
160, 180, 195, 200 +/-4 4 - 6.3
>200 - 350 +/-5 3 - 5.3

Sizes and tolerances apply to the rolled/forged condition.

Peel turned round billets
Size Tolerance Length
mm mm m
75 - 200 (5 mm interval) +/-1 max 10
>200 - 450 +/-3 3 - 8
Unground round billets
Size Tolerance Length
mm mm m
77 - 112 (5 mm interval) +/-2 max 10
124, 134 +/-2 max 10
127, 147, 157 +/-2 max 10
142, 152, 163 +/-2 max 10
168, 178, 188 +/-2 max 10
183, 193 +/-2 max 10

Other products

  • Welded tube and pipe
  • Seamless tube and pipe
  • Strip, annealed or cold-rolled to different degrees of hardness

Heat treatment

Billets are delivered in the hot worked condition. The following heat treatment is recommended.

Solution annealing

1050-1150°C (1920-2100°F), followed by quenching in water.

Mechanical properties

Testing is performed on separately solution annealed and quenched test pieces.

The following figures apply to material in the solution annealed condition.

At 20°C (68°F)

Metric units
Proof strength Tensile strength Elong Hardness
Rp0.2a) Rp1.0a) Rm Ab) Brinell
MPa MPa MPa %
≥230 ≥250 530-720 ≥40 ≤230
Imperial units
Proof strength Tensile strength Elong Hardness
Rp0.2a) Rp1.0a) Rm Ab) Brinell
ksi ksi ksi %
≥33 ≥36 77-104 ≥40 ≤230

1 MPa = 1 N/mm2
a) Rp0.2 and Rp1.0 correspond to 0.2% offset and 1.0% offset yield strengths, respectively.
b) Based on L0 = 5.65 √S0 where L0 is the original gauge length and S0 the original cross-section area.

Impact strength

Due to its austenitic microstructure, Alleima® 2RK65™ has very good impact strength both at room temperature and at cryogenic temperatures. Tests have demonstrated that the steel fulfils the requirements (60 J (44 ft-lb) at -196 oC (-320 oF)) according to the European standards EN 13445-2 (UFPV-2) and EN 10216-5.

At high temperatures

The steel should not be exposed to temperatures above about 550 °C (1020 °F) for prolonged periods, since this leads to precipitation of intermetallic phases, which can have an adverse effect on both the mechanical properties and the corrosion resistance of the steel. Minimum proof strength properties at high temperatures are based on datasheets seamless tubes and pipe. Since the tubes have thin walls the values should only be used as indicative values for billets.

Metric units
Temperature
Proof strength
Rp0.2 Rp1.0
°C MPa MPa
min. min.
100 176 205
200 155 185
300 136 165
400
125
155
Imperial units
Temperature
Proof strength
Rp0.2 Rp1.0
°F ksi ksi
min. min.
200 26.1 30.3
400 22.4 26.7
600 19.5 23.7
700
18.6
22.9

Physical properties

Density: 8.0 g/cm3, 0.29 lb/in3

Thermal conductivity
Temperature, °C W/(m °C) Temperature, °F Btu/(ft h °F)
20 12 68 7
100 14 200 8
200 16 400 9
300 18 600 10.5
400 20 800 11.5
500 22 1000 13
600 23 1200 14
700 25 1300 14.5
Specific heat capacity
Temperature, °C J/(kg °C) Temperature, °F Btu/(lb °F)
20 460 68 0.11
100 485 200 0.12
200 515 400 0.12
300 545 600 0.13
400 570 800 0.14
500 590 1000 0.14
600 605 1200 0.15
700 615 1300 0.15
Thermal expansion, mean values in temperature ranges (x10-6)
Temperature, °C Per °C Temperature, °F Per °F
30-100 15.5 86-200 8.5
30-200 16 86-400 9
30-300 16.5 86-600 9
30-400 17 86-800 9.5
30-500 17 86-1000 9.5
30-600 17.5 86-1200 9.5
30-700 17.5 86-1300 10
Resistivity
Temperature, °C μΩm Temperature, °F μΩin.
20 0.94 68 37.0
100 0.99 200 38.8
200 1.07 400 42.2
300 1.13 600 44.6
400 1.15 800 45.5
500 1.17 1000 45.8
600 1.15 1200 45.9
700 1.18 1300 46.5
Modulus of elasticity (x103)
Temperature, °C MPa Temperature, °F ksi
20 195 68 28.5
100 190 200 27.5
200 182 400 26.5
300 174 600 25
400 166 800 24
500 158 1000 22.5

Hot working

Hot working should be carried out at a material temperature of 900-1200°C (1650-2190°F). Hot working of Alleima® 2RK65 should be followed by rapid cooling in air or water. Subsequent heat treatment should be carried out in accordance with the recommendations given for heat treatment.

Welding

The weldability of Alleima® 2RK65 is good. Welding must be carried out without preheating, and normally there is no need for any subsequent heat treatment. Suitable methods of fusion welding are manual metal-arc welding (MMA/SMAW) and gas-shielded arc welding, with the TIG/GTAW method as first choice.

For 2RK65, heat-input of <1.0 kJ/mm and interpass temperature of <100°C (210°F) are recommended. A string bead welding technique should be used.

Recommended filler metals

TIG/GTAW or MIG/GMAW welding

ISO 14343 S 20 25 5 Cu L/ AWS A5.9 ER385 (e.g. Exaton 20.25.5.LCu)

MMA/SMAW welding

ISO 3581 E 20 25 5 Cu N L R/ AWS A5.4 E385-16 (e.g. Exaton 20.25.5.LCuR)

Machining

The machining of Alleima® 2RK65, as with other stainless steels, requires an adjustment to, tooling data and machining method, in order to achieve satisfactory results. Compared to Sanmac® 316/316L, the cutting speed must be reduced by approximately 40-45%, when turning Alleima® 2RK65 with coated, cemented carbide tools. Much the same applies to other operations. Feeds should only be reduced slightly and with care.

Detailed recommendations for the choice of tools and cutting data are provided in the data sheet for Sanmac® 316/316L.

Disclaimer: Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice. This datasheet is only valid for Alleima materials.