Weight
C
%
Cr
Ni
Mo
Mn
Si
P
S
N
Cu
W
ER
0.03
82.5- 2.5 1
0.03 0.02 0.20- 1.5 1.0
24-27
2594
max
10.5 4.5
max max max max 0.30 max max
Alloy ER 2594 is a superduplex welding wire. The Pitting Resistance Equivalent
Number (PREN) is at least 40, thereby allowing the weld metal to be called a
superduplex stainless steel. This welding wire provides matching chemistry and
mechanical property characteristics to wrought superduplex alloys such as 2507
and Zeron 100 as well as superduplex casting alloys (ASTM A890). This welding
wire is overalloyed 2-3 percent in Nickel to provide optimum ferrite/austenite
ratio in the finished weld. This structure results in high tensile and yield strength
along with superior resistance to SCC and pitting corrosion.
Set the parameters to obtain a heat input of 10,000 -30,000 Joules/inch. Preheat is not required. The interpass temperature should be maintained at 300ºF
max. If post weld annealing is required this weld metal will require a higher
annealing temperature than that required by the duplex base metal.
Alloy ER 2594 is a Stainless Steel TIG, MIG and SUB-ARC wire used for
welding. For all stock availability contact Sales.
Specifications
AWS 5.9 ASME SFA 5.9 AWS ER2594 UNS 32750
Pitting Resistance Equivalent Number
Pitting resistance equivalent number (PREN) is a predictive measurement of
a stainless steel's resistance to localized pitting corrosion based on its chemical
composition. In general: the higher PREN-value, the more resistant is the stainless
steel to localized pitting corrosion by chloride.
PREN is frequently specified when stainless steels will be exposed to seawater or
other high chloride solutions. In some instances stainless steels with PREN-values >
32 may provide useful resistance to pitting corrosion in seawater, but is dependent on
optimal conditions. However, crevice corrosion is also a significant possibility and a
PREN > 40 is typically specified for seawater service.
These alloys need to be manufactured and heat treated correctly to be seawater
corrosion resistant to the expected level. PREN alone is not an indicator of corrosion
resistance. The value should be calculated for each heat to ensure compliance with
minimum requirements, this is due to chemistry variation within the specified
composition limits.
There are several PREN formulas. They commonly range from:
PREN = %Cr + 3.3 × %Mo + 16 × %N
to: PREN = %Cr + 3.3 × %Mo + 30 × %N.[4]
There are a few stainless steels which add tungsten (W), for those the following
formula is used: PREN = %Cr + 3.3 × (%Mo + 0.5 × %W ) + 16 × %N
All % values of elements must be expressed by mass, or weight (wt. %), and not by
volume. Tolerance on element measurements could be ignored as the PREN value is
indicative only.