Page 3 - SD 2304
P. 3
mV/SCE
Pitting potential versus temperature
1000 obtained by polarisation curves °F
750 SD 2304
500 NaCl 30 g/l
316L
250
304L
304L 316L SD 2304
Guaranteed
25 50 75 °C
75 120 165 °F
Stress corrosion resistance
Stress corrosion resistance test results
Cracks in chloride containing aqueous solutions
(8ppm 0 2 ) PH =7, >1000 h, applied
SD 2304
stresses higher than the yield strength)
No cracks show that SD 2304 grade outperforms
304L and 316L grades, due to its high
chromium additions and low nickel
cracks contents.
This is a typical feature of duplex
no cracks
stainless steels. UR 45N performs still
10 4 better than SD 2304 in similar
ppm Cl - conditions.
SD 2304
Other corrosion resistance properties
SD 2304 duplex stainless steel successfully passes most of the standard IC test
procedures such as ASTM A262E and C tests. Its corrosion rate in boiling nitric
acid (65%) is higher than that of 316L grade. Due to its high yield strength, the
alloy performs well in abrasion/corrosion applications.
PROCESSING Hot forming
Hot forming must be carried on in the 1150/900°C ( 2100/1650°F) temperature
range.
After forming, a new solution annealing treatment is recommended in the
950/1050°C ( 2100/1650°F) temperature range to fully restore corrosion resistance
properties and mechanical properties. Parts of SD 2304 must be supported
carefully during heating to avoid creep deformation.
Cold forming
SD 2304 may be cold formed without any problem. The same equipments as those
used for the cold forming of 304 and 316 grades can be used. Due to its higher
mechanical properties, including the yield strength, higher stresses are required for
cold forming. A final solution annealing heat treatment is also recommended after
cold forming in order to restore the mechanical and corrosion resistance
properties, as decribed in ‘hot forming’.
Descaling
Use the same solutions and pastes as for 304/316L grades. The pickling time will
be higher than for austenitic grades due to the corrosion resistance properties of
the alloy.
