Duplex Stainless Steel Tank Plate Welding Guide

Material Properties and Challenges:
Welding duplex stainless steel tank plates requires balancing the ferrite/austenite ratio (ideal value 40-60%). Excessive heat input can lead to excessive δ-ferrite. ER2209 welding wire is recommended, as its PREN value is 4-6 points higher than ordinary welding wire, significantly improving corrosion resistance.

Process Parameter Control:
For 2mm thin plates, use a current of 50-80A and an argon gas flow rate of 8-12L/min. For medium and thick plates, multiple passes are required, with an interpass temperature of ＜150℃. Use a 98%Ar+2%N₂ mixed gas for shielding, and the nitrogen element burn-off rate can be controlled within 5%.

Defect Prevention Measures:
A V-groove angle of 70° is recommended, combined with a 0.8-1.2mm root face gap, which can increase the first-pass acceptance rate to 98.5%. When the humidity is >70%, dehumidification equipment must be used, and the dew point should be <-40℃ to avoid hydrogen porosity.

Quality Verification Standards:
In addition to conventional PT/RT testing, the ferrite content within 2mm of the fusion line must be determined using the magnetic method (acceptable range 55%±3%). The impact energy of the 45° uphill welding position needs to be additionally tested, and a reduction of 25-30J is allowed compared to flat welding.