Page 6 - SD 2507Cu

WELDING SD 2507Cu can be welded using the following processes : SMAW, GTAW (with
filler), GMAW, PAW (with filler).

The welding procedures are similar to those of other duplex stainless steels :

- no pre-heating,

- heat input between 0.5 KJ/mm and 2 JK/mm is recommended (depending
on the process and on the thickness of the plate). Precise welding
parameters for each type of process and thicknesses are available on
request.
- interpass temperature less than 150°C ( 302°F) and preferably less than
120°C (248°F)
- no PWHT, except solution annnealing at 1080/1120°C ( 1976/2048°F) +
water cooling.

As in welded conditions, the ferrite ratio in the heat affected zone should be lower
than 70% between 20 to 60% for the weld metal ; for SMAW, FCAW and SAW
weld metal aim for the lower part of the range (20 to 40%).

In order to control the structure and properties, over alloyed filler materials are
recommended (nickel and/or nitrogen additions). Excessive dilutions must be
avoided.

Filler materials and shielding gases guaranteeing PREN > 40 have been
developed (wire, metallic cored wire, electrodes) - a list of tested filler materials is
available on request.

CRITICAL PITTING TEMPERATURE ON WELDED STRUCTURE - ASTM G48A
GRADE FILLER CORROSION CRITERIA : > 10 mg WEIGHT LOSS
316L 316 L
UR 45 N 22 Cr duplex

UR 45 N+ 25 Cr duplex
UR 825 625
UR B6 625

UR 52N+ 25 Cr Duplex
UR 52N+ Alloy H.C22

20 25 30 35 40 45 50 55 60 65 70 CPT°C
70 75 85 93 105 113 120 131 140 150 160 CPT°F

Corrosion resistance properties of welded structures are very dependant on
welding parameters and surface condition. Avoid oxyde scales or contaminations.
Brushed or pickled welds perform better. The best results are obtained for solution
annealed welds. The use of nickel based weld consumables allow to increase the
corrosion resistance of welded structures (avoid 625 alloys but use Nb free grades
like H.C22 or SG Ni Cr 23 Mo 16 or PHYWELD NCM (Nb free 625).