These corrosion data are mainly based on results of general corrosion laboratory tests, carried out with pure chemicals and water solutions nearly saturated with air (the corrosion rate can be quite different if the solution is free from oxygen).

All concentrations are given in weight-% and the solvent is water if nothing else is shown. The corrosion data apply to annealed materials with normal microstructure and clean surfaces, throughout.

Fluosilicic acid, H2SiF6
Conc. H2SiF61111
Temp. °C60657075
Grade or type of alloy:
Carbon steel
13 Cr
Alleima® 1802
Alleima® 3R12
Alleima® 3R601
18Cr13Ni3Mo 1)
17Cr14Ni4Mo 2)
Alleima® 2RK65 ('904L')01
Sanicro® 28
254 SMO0001
654 SMO0000
SAF™ 23040011
SAF™ 220500
SAF™ 25070000
Titanium (CP Ti)

1) ASTM 317L, e.g. Alleima® 3R64
2) EN 1.4439, e.g. Alleima® 3R68

Fluosilicic acid, H2SiF6
Conc. H2SiF6 %5555101010202020202031313131
Temp. °C50556570354045203040506020304045
Grade or type of alloy:
Carbon steel2
13 Cr2
Alleima® 18021
Alleima® 3R121
Alleima® 3R6011211
18Cr13Ni3Mo 1)
17Cr14Ni4Mo 2)
Alleima® 2RK651010111
Sanicro® 28011
254 SMO0101001101
654 SMO000100010001
SAF™ 2304112222222
SAF™ 220511122
SAF™ 250700101100122
Titanium (CP Ti)1

1) ASTM 317L, e.g. Alleima® 3R64
2) EN 1.4439, e.g. Alleima® 3R68

Symbol clarification

These corrosion tables use a number of symbols, having the following meanings:

Symbol Description
0 Corrosion rate less than 0.1 mm/year. The material is corrosion proof.
1 Corrosion rate 0.1—1.0 mm/year. The material is not corrosion proof, but useful in certain cases.
2 Corrosion rate over 1.0 mm/year. Serious corrosion. The material is not usable.
p, P Risk (severe risk) of pitting and crevice corrosion.
c, C Risk (Severe risk) of crevice corrosion. Used when there is a risk of localised corrosion only if crevices are present. Under more severe conditions, when there is also a risk of pitting corrosion, the symbols p or P are used instead.
s, S Risk (Severe risk) of stress corrosion cracking.
ig Risk of intergranular corrosion.
BP Boiling solution.
ND No data. (Used only where there are no actual data to estimate the risk of localised corrosion instead of p or s).

Disclaimer: Laboratory tests are not strictly comparable with actual service conditions. Accordingly, Alleima makes no warranties, express or implied, and accept no liability, compensatory or consequential, for the performance of different materials in individual applications that may be based on the information provided in this publication.