Hi!
Sudhakar,
Welding consumables for duplex stainless steels need to be higher in elements (generally higher Nickel in the filler as compared to the base metal- for filler wire Ni could be in the range of 7.0 to 7.5% as compared to ˜4.8 % in the plate) promoting austenite formation, compared to the corresponding parent material, to avoid excessively high weld metal ferrite contents and to ensure appropriate mechanical properties and corrosion resistance. Welding duplex 2304 (1.4362/S32304) should be done with an over alloyed filler such as the matching Avesta 2304. There are number of reasons why it is recommended using a consumable with a composition more closely matching the leaner parent material 2304 then welding with the conventional over-alloyed 2209 filler.(the prominent reason could be the cost advantage as compare to 2209 filler metal- There is an obvious cost advantage when the Nickel- and Molybdenum content are decreased.)
The best weldment properties can be obtained by using designed filler material such as Avesta 2304. The relatively low nitrogen content makes it possible to weld with high speed & with good penetration. The low molybdenum content is the main reason why it is not sensitive to deleterious precipitation during welding, but traces of nitrides may be found in the HAZ and the weld metal.
GTAW can be carried out with pure argon as shielding gas. Autogenous welding shall be carried out with nitrogen addition to the shielding gas to increase strength. Gases for GMAW recommended are Ar+30% He+2.5% CO2 or Ar+2%CO2/Ar+2% CO2 and the gases could be the same for GMAW welding of LDX-2101. If you are planning to do SAW welding use of basic flux is recommended to increase the ductility.
S32304 can be welded using heat input of max. 2.0kJ/mm and this would ensure not having any negative effect on microstructure and other properties.
At the same time duplex should not be welded with too low heat input. Theoretical minimum heat input is 0.5 kJ/mm for 2304. Inter pass temperature should be below 150.
Hope this is line with your requirements.
Thanks and regards,
KAMAL SHAH
Dear members,
I would like to get some inputs from all of u regarding Lean duplex steels (LDSS) 32304.
Mostly about welding of LDSS, selection of consumables and any important measures to be taken.
Highly appreciated if consumables brands are recommended.
Rgds
Sudhakar
Sent from my iPhone
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