Page 5 - SD 2507Cu

Stress corrosion cracking resistance

The stress corrosion resistance properties of SD 2507Cu is excellent in high
temperature chloride containing solutions as well as in sour gas applications.

FABRICATION
°C °F MPa Rp 0.2 %
300 SD 2507Cu570 Stress threshold
Super duplex 500
No cracking
400
200 390
UR 45N
300
UR 35N
200
100 210
AISI 304/316 100

0
32

0 0.001 0.1 10 Cl (%) 304L 316L UR52N 904L
-
Constant-strain tests in autoclave Stress corrosion cracking in chloride media :
Above the curve, SCC occurs. 300 g/l NaCl - T = 110°C - pH = 1
Open circles means no SCC for UNS 32550/UR 52N + Threshold stress without crack after 1 month
Chloride (mg/l)
Austenitic Duplex 1000000 MR 01-75 limits
SCC 316L 170 HE URB6 UR45N UR47N UR52N
resistance for 22 Cr and 25 Cr duplex

10 100000 CRACKING
CRACKING
S 32550
20 S 31803
UR 45N UR 52N + NO
CRACKING
30 10000 NO CRACKING

40
Loss of ductility
1000
0.01 0.1 Hydrogen Sulphide (psi) 10 100
1
-6
Slow strain rate tests (10 /sec) in NaCl, 40% pH=2 (HCl),
110°C - Elongation in air - Elongation in corrosive medium Suggested limits for Duplex
and Super duplex stainless steels

Cold forming

Due to its higher mechanical properties, the cold forming of SD 2507Cu requires
more strength than austenitic grades. For cold deformations higher than 20 %, an
intermediate heat treatment is required (solution annealing 1080/1120°C
(1976/2018°F) + water cooling).

Detailed guidelines for cold forming of unwelded and welded plates are available
upon request.

Hot forming

Between 1150°C and 1000°C ( 2102 and 1832°F). After hot forming, a new solution
annealing heat treatment in the range 1080/1120°C ( 1976/2018°F) + water cooling
is necessary.

Pickling

Same conditions as for 316L grade, but the pickling time is at least twice that of
316L grade. An increase of the temperature of the pickling bath reduces the
pickling time.