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| For the Urea / Fertilizer Industry . Material No. 1.4465 |
Steel material No. 1.4465 is a fully austenitic Chromium-Nickel-Molybdenum steel with an extremely low Carbon content. The material is distinguished by very low corrosion rates at the Huey-test, and it is applied especially in those parts of Urea plants which are subjected to the most corrosive conditions.
1. Material description X2CrNiMoN 25-25-2
Material No. (1.4465) , UNS N 08310
2. Supply form and condition seamless tubes, pickled
(sheets, 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/cm2
Spec. electrical resistance 0,90 Ohm mm2/m
Thermal conductivity 15 W/m °C
5. Heat treatment
Quench annealing: 1050-1150 °C/water
Bright annealed: 1050-1150 ° C/gas
6. Welding
The weldability of Material No. 1.4465 can be described as good. For welding into tubes (pipes) sheets welding rods as well as the TIG welding process can be used. As welding additives we recommend for the above processes S-NiCrFe27MoCu Material No. 1.4455, depending on application. Heat treatment (pre-or subsequent heating, resp) is generally not required. As usual with austenitic Cr-Ni-steels, Material No. 1.4465 must also be welded with the least possible heat input.
7. Cold bending
There is generally no need for heat treatment after cold bending to usual bending radii. At a higher degree of deformation and operational conditions, which may suggest danger of stress corrosion cracking, heat treatment at 1050-1150 °C is recommended.
8. Hot bending
Hot bending should be carried out at a temperature range of 1150-850 °C. A quenching after hot forming can be advisable in some cases for maintaining the optimum corrosion performance. At rapid quenching from the hot forming temperature a subsequent annealing is generally not necessary.
9. Corrosion resistance
Material No. 1.4465 is distinguished from similar alloy steels not only by a better performance is respect of the corrosion rate, but also by higher resistance when subjected to pitting, stress corrosion cracking and inter-crystalline corrosion.
a. Intercrystalline corrosion
The excellent resistance to inter crystalline corrosion is proved by the Strauss-test
(SEP 1875-61 / DIN 50914) as well as the Huey-test (ASTM A 262, Practice C.)
b.Huey-test
Apart from the testing for resistance to grain disintegration the Huey-test also serves for investigating whether there are any further inhomogeneities such as precipitations within the grain, sigma phase and inclusions of Ferrite. For this reason the Huey-test represents
a very strict testing method, which includes a great number of parameters. Material No. 1.4465 has a max. corrosion rate of 1,5 μm/48h= 5,91 g/m2 24h=0.27 mm/year at the Huey-test. This extraordinarily low value can only be guaranteed by special provisions at the production of the steel and by extensive quality control during the various of production.
c.Pitting corrosion
Due to the Molybdenum content and the increased Chromium content there is a good corrosion resistance to flowing waters containing Chlorides.
d.Stress corrosion cracking
Due to the increased Nickel content, Material No. 1.4465 has a considerably higher range of resistance to stress corrosion cracking than e.g. X2CrNiMo 1812 (TP 316 L)
e.Special environments
Material No. 1.4465 offers excellent corrosion resistance to a great number of corrosion environments. Especially worth noting here is the good performance in Nitric acid, Phosphoric acid and the Ammonium carbamate solution occurring in the Urea process.
10. Application
Urea plants
Material No. 1.4465 has been developed for the especially high requirements in strippers of Urea plants to the Stamicarbon process route. This steel can also be successfully used, however, for other processes, where similar operational conditions exist as in the stripping process.
Nitric acid plants
Due to the very small corrosion rates at the Huey-test, Material No. 1.4465 is suitable for the application in Nitric acid plants and in equipment that is subjected to Nitric acid.
Other plants
Because of the increased corrosion performance as against comperable steels such as
X3CrNiMoN 2525, X2CrNiMo 1810 and X2CrNi 189 the application of Material No. 1.4465 should be also considered, if the former steels have failed to produce satisfactory results. |
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