(supersedes all previous editions)
Alleima® 6R35 is an austenitic, titanium-stabilized stainless chromium-nickel steel. It is suitable for wet-corrosive service but also has good mechanical strength at high temperatures.
PED (Pressure Equipment Directive) 2014/68/EU and AD2000
Good resistance to hydrogen sulfide gas and intergranular corrosion coupled with good high temperature strength make Alleima® 6R35 a suitable material for applications as tubes in heating furnaces and heat exchangers in sulfurization and hydro-treating plants. In the petrochemical industry the steel is used in cracking furnaces for the production of ethylene and vinyl chloride. It is also frequently used for heat exchangers and piping in the chemical and petrochemical industries.
Alleima® 6R35 has with some limitations (nitric acid) the same resistance as the unstabilized steel ASTM 304. Consequently, the grades have good resistance to
The stabilization with titanium gives Alleima 6R35 improved resistance to intergranular corrosion.
Pitting and crevice corrosion may occur even in solutions of relatively low chloride content. However, the stabilization with titanium results in a somewhat better resistance than that of ASTM 304.
Austenitic steels, like Alleima® 6R35 are susceptible to stress corrosion cracking. This may occur at temperatures above about 60°C (140°F), if the material is subjected to tensile stresses and at the same time comes into contact with certain solutions, particularly those containing chlorides. Such service conditions should therefore be avoided. Conditions when plants are shut down must also be considered as the condensates which are then formed can develop a chloride content that leads to both stress corrosion cracking and pitting.
In applications demanding high resistance to stress corrosion cracking we recommend the austenitic-ferritic steel SAF™ 2304.
Alleima® 6R35 can be used in:
Creep should also be taken into account when using the steel in the creep range.
In flue gases containing sulfur, the corrosion resistance is reduced. in such environments this steel can be used at temperatures up to 600-750°C (1110-1380°F) depending on service conditions. Factors to consider are whether the atmosphere is oxidizing or reducing, i.e. the oxygen content, and whether impurities such as sodium and vanadium are present.
Annealing after cold bending is not normally necessary, but this point must be decided with regard to the degree of bending and the operating conditions. Heat treatment, if any, should take the form of stress-relieving or solution annealing.
Hot bending is carried out at 1100-850°C (2010-1560°F) and should be followed by solution annealing.
Seamless tube and pipe in Alleima® 6R35 is supplied in dimensions up to 260 mm outside diameter in the solution-annealed and white-pickled condition or solution-annealed in a bright-annealing process.
Hollow bars are supplied solution-annealed and white-pickled.
Seamless tube and pipe
Seamless tube and pipe are stocked in a wide range of sizes according to ISO and ANSI both in hot extruded as well as in the cold finished and annealed condition. Details of our manufacturing and stock programme are given in catalogue S-110-ENG.
Hollow bar is stocked in large number of sizes. Our standard size range for stock comprises 32-250 mm (1.3-9.8 in.) O.D. See catalogue S-110-ENG.
The tubes are normally delivered as described above. If additional heat treatment is needed after further processing the following is recommended.
1040-1100 °C (1905-2010 °F), 2-5 min, rapid cooling in air or water.
Stabilization treatment: 1040-1100 °C (1920-2010 °F), 2-5 min rapid cooling in air or water. However, annealing above 1100°C (2010 °F) may be required in order to meet grain size requirements. This treatment should be followed by a stabilization treatment.
850-950 °C (1560-1740 °F), 10-15 minutes, cooling in air.
At 20°C (68°F)
|Proof strength||Tensile strength||Elong.||Hardness|
1 MPa = 1 N/mm2
a) Rp0.2 and Rp1.0 correspond to 0.2% offset and 1.0% offset yield strength, respectively.
b) Based on L0 = 5.65 √S0 where L0 is the original gauge length and S0 the original cross-section area.
c) NFA 49-117 and NFA 49–217 with min 45% can be fulfilled.
Due to its austenitic microstructure, Alleima® 6R35 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
|Temperature||Proof strength c)|
|Temperature||Proof strength c)|
c) For extruded tube and pipe with wall thickness greater than 10 mm (0.4 in.) the proof strength may fall short of the stated value by 20 MPa (2.9 ksi) at 100°C (200°F) and by 10 MPa (1.4 ksi) in the temperature range 200-600°C (400-1100°F).
|Temperature||10 000 h||100 000 h|
Density: 7.9 g/cm3, 0.29 lb/in3
|Temperature, °C||W/m °C||Temperature, °F||Btu/ft h °F|
|Temperature, °C||J/kg °C||Temperature, °F||Btu/lb °F|
|Temperature, °C||Per °C||Temperature, °F||Per °F|
1) Mean values in temperature ranges (x10-6)
|Temperature, °C||MPa||Temperature, °F||ksi|
The weldability of Alleima® 6R35 is good. Welding must be carried out without preheating and subsequent heat treatment is normally not required. 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 Alleima® 6R35, heat input of <1.5 kJ/mm and interpass temperature of <150°C (300°F) are recommended.
TIG/GTAW or MIG/GMAW welding
ISO 14343 S 19 9 Nb / AWS A5.9 ER347 (e.g. Exaton 19.9.Nb)
ISO 3581 E 19 9 Nb R / AWS A5.4 E347-17(e.g. Exaton 19.9.NbR )
ISO 14343 S 19 9 Nb / AWS A5.9 ER347 (e.g. Exaton 19.9.LNb) wire or strip electrodes are recommended for overlay welding of tube sheets and high-pressure vessels in cases where corrosion resistance, equal to that of Alleima 6R35, is required.
Alleima® 6R35 has good machining properties. Please contact Alleima for detailed recommendations on the choice of tools and cutting data.
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.