Page 3 - SD 2507

General corrosion

SD 2507 grade performs nearly as well as highly alloyed austenitic stainless steels
in most of inorganic acids. For sulphuric acid solutions, copper containing, super-
duplex grades should be prefered.

SD 2507 is suitable for uses in organic acids including high concen-trations and
temperatures where austenitic stainless steels corrode at a higher rate.

Corrosion rate
Boiling curve
(mdd)
100 212 80 White liquor :
CLI-SAF 2507 70 NaOH : 125 g/l
Na 2S : 50 g/ll
60 Na 2/So 4 : 16 g/l
80
176
Temperature (°C) 60 S32520 140 Temperature (°F) 40 304L Sulfidity : 21 %
50
Na 2CO 3 : 27 g/l
H2S bubbling
30 316L
20
N08904
N08926
10 UR 45N
40 316 104 0 CLI/SAF 2507
S31803 20 40 60 80 100
316 Chloride concentration (g/l)
20 68 Heat transfer (solution 140°C - Sample 80°C)
0 20 40 60 80 100 Pulp and Paper industry
H 2 SO 4 (% wt) Corrosion rate versus chloride content in Kraft media

Medium : NaCl 30g/l + Fe 2 (SO 4 )3 0,1 % - pH = 2 aerated Chloride
T = 60°C Test duration 15 days concentration (ppm)
Corrrosion rate
(mdd) 2000 CLI-SAF 2507

3 00 0 ppm F - 1600
1000 ppm F - UR B6
1200 UR 45N
2 00
800 317 LNM
317 LN
316 LN
1 00 316L
400
No
0 Corrosion 20 60 80 120 (°C)
316L 317LNM UR45N N08904 SD 2507 68 140 176 216 (°F)
Pollution control equipments

Effects of fluoride contents on the uniform corrosion rate Safe use limits of stainless steels versus
chloride content and temperature in 54 % P205

mm/year (mpy)
0.25(10) 50% acetic acid °C /°F
0.20(8) Boiling point curve
AISI AISI Test time 120/250
316L
317L
1+ 3+ 3 days
0.15(6) 100/210
SD 2507
0.10(4) UR B28 80/175 UR B28
SD 2205
0.05(2) 60/140 AISI
316L
SD 2507
0 No attack 30/ 85
25
0 5 10 15 20 HCOOH, weight % 1 2 3 4 % HCl
Corrosion rate in boiling mixtures of 50% acetic acid Isocorrosion diagram in hydrochloric acid
Corrosion rate of 0.1mm/year (4mpy)
and varying proportions of formic acid in stagnant test solution

Pitting and crevice corrosion
The minimum PREN value ( [%Cr] + 3.3[% Mo] + 16[%N] ) of 40 also explains
why the alloy is highly resistant to pitting and crevice corrosion. The alloy behaves
much better than 904L and is, for pitting corrosion resistance, nearly equivalent to
6 Mo super g grade. In some cases, the crevice corrosion resistance is slightly
higher than 6 Mo alloys due to the 25% Cr additions.