Page 5 - SD 2205

Corrosion fatigue resistance
MPa KSI
Duplex stainless steels combine high 60
mechanical and corrosion resistance 400
properties. The fatigue corro-sion data SD 2205
presented are very attractive results 300 45
7
since after 10 cycles, fatigue limit
remains at least twice that of 316
austenitic stainless steels. 200 316L 2.5 Mo
316 30

5
Synthetic sea water solution 10 6 7
( smooth samples) 10 10
Cycle to rupture

PROCESSING Hot forming

Hot forming should be carried out in a temperature range of 1150-950°C ( 2100-
1750°F) after the piece has been uniformly heated. At temperatures lower than
950°C (1750°F), the alloy is very prone to intermetallic phase precipitatioans such
as sigma phase. This affects the toughness and corrosion resistance properties of
SD 2205.

A final full annealing heat treatment (1040-1080°C / 1900-1975°F) followed by
rapid quench, is required (to restore phase balance, mechanical and corrosion
resistance properties).

Special precautions must be taken during heat treatment to avoid deformations.

Cold forming

SD 2205 can be cold formed without any
problem using equipments suited to work MPa KSI
stainless steel. The duplex SD 2205 alloy 930 Tensile strength 135
requires more power than austenitic
stainless steels due to its higher mechanical 830 Yield strength 120
properties and work hardening (which is
lower than for austenitic steels). Cold
working ratios exceeding 20% require an 720 105
intermediate full annealing heat treatment 620 90
(1040/1080°C - 1900/1975°F). Such heat 520 Elongation (E%) 75
treatment is also recommended after cold
forming of more than 10 % in order to
restore its properties. 5 10 15 20 E%
Cold forming

Pickling
Pickling solutions or pastes acceptable for alloy 316 L may be used. The pickling
time required is at least twice that of 316L. A slight increase of the temperature of
the pickling bath reduces the pickling time. Typical pickling conditions are (10 %
HNO 3 - 2% HF) 60°C ( 140°F). Passivation decontamination treatments may be
performed with a 10-25% nitric acid solution.