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| Steel Material No. 1.4439 |
Steel Material No. 1.4439 is a fully austenitic chromium-nickel-molybdenum-steel with increased resistance to pitting corrosion
1. Material description X2CrNiMoN 17135
Material No. 1.4439
AISI 317LNM
(SEW 400)
2. Supply form and condition seamless tubes, annealed
(plates, strips, rods, forgings)
3. Range of dimensions (Tubes) Outside Diameter: . ..10-114 mm
Wall Thickness: ...... ...... ...... ...... ...... ...... .1-12 mm
Length: ...... ...... ...... ...... ...... ...... ......max. 26.5 m
(depending on diameter and wall)
4. Physical properties
Density 7.9 g/cm
Electrical resistance 0.85 Ohm mm/m
Thermal conductivity 15 W/M°C
Linear coefficient of expansion 20-100°C 16.5 106 m/m°C
20-200°C 17.5 106 m/m°C
20-300°C 17.5 106 m/m°C
20-400°C 18.5 106 m/m°C
Modulus of elasticity 200 103 N/mm2
5. Heat treatment
Recrystallization 1050-1150 °C/air/water
Stress-relieving 500-600 °C/air
6. Welding
Electrode rod welding as well as the WIG (TIG)-method is suitable for welding tubes into tubes (pipes) plates. The use of additives of the same type is recommended in order to obtain a weld free of ferrites and with the favourable properties of the basic material. Welding should be carried out with as little heat as possible. There is usually no need for further heat treatment.
7. Cold bending
Heat treatment is in most cases not necessary after cold bending to normal bending radii. At a higher degree of forming and at operational conditions which could cause stress corrosion in austenitic steels, a stress-relieving annealing is recommended.
8. Corrosion resistance
The addition of nitrogen provides a good austenitic stability for Material No. 1.4439 giving it a superior corrosion resistance to that of 1.4435. Even after heat treatment e.g. welding, a good corrosion resistance is maintained as there is no possiblity of the formation of harmful phases e.g. the sigma phase. The increased molybdenum content affords a high corrosion resistance in chlorine-ioncontaining media. Pitting corrosion resistance is particularly improved.Material No. 1.4439 is characterized by good resistance in Mixed acids -sulphuric acid / nitric acid,Hydrofluoric acid, nitric acid. Bleaching solutions -sodium chlorite, sodium-hypochloriteSea and brackish water -sodium chloride
9. Application
Positive experiences with Material No. 1.4439 can be expected amongst others in the following applications:
Fatty acid plants
Bleaching plants
Nuclear evaporation plants
Plants admitting aqueous chloride solutions |
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