Duplex stainless steel pipe welding process

1. Using 99.99% argon inert gas protection, the manual tungsten argon arc welding bottom welding includes the following process steps:
(1) The selected power supply is a Panasonic TSP-300 manual/argon arc welding machine, the polarity of the power supply is DC positive connection, the protective gas of the molten pool is 99.99% argon, the flow rate is 10-18 liters/minute, and the back protective gas is 99.99% % argon, argon arc welding wire is Lincoln LNT4462Φ2.0, AWSA5.9: ER2209, tungsten pole thorium tungsten pole Φ2.4, ANSI/AWSA5.12-92, the welding position is fixed horizontally, the wall thickness is 8-10mm, The joint form is a butt V-shaped joint, the groove angle is 60°±5°, the blunt edge is 0-1.5 mm, and the gap is 3-5 mm;
(2) Fix the assembled workpiece horizontally on the welding frame, and only the gas inlet and outlet are left at the nozzle of the sealed duplex stainless steel tube. Argon gas is used as the back protection gas in the tube of the duplex stainless steel tube for 3-5 minutes, and the gas flow rate is 5-10 liters/minute;
(3) The certified welder conducts bottom welding, the current is 70-90 amperes, the voltage is 11-13 volts, the welding speed is 30-50 mm/min, and the back shielding gas is continued;
(4) After the whole circle is welded, carry out the second layer of heat welding, the current is 105-150 amps, the voltage is 13-18 volts, the welding speed is 75-130 mm/min, and the flow rate of molten pool protective gas is 10-15 liters/ Minutes, control interlayer temperature ≤ 150°C;
(5) After the second layer is welded, continue to pass the shielding gas.
2. Using 80% argon plus 20% carbon dioxide gas protection for semi-automatic filling and capping welding includes the following process steps:
(1) The selected power supply is a Panasonic KRII-350 carbon dioxide welding machine, the polarity of the power supply is DC reverse connection, the protective gas of the molten pool is 80% argon + 20% carbon dioxide, the back protective gas is 99.99% argon, and the flux cored wire For Lincoln Cor-A-RostaP4462Φ1.2, AWSA5.22: E2209T1-4;
(2) Measure the temperature of the weld seam that has been thermally welded, and keep the interlayer temperature ≤ 150°C;
(3) Filler welding by certified welders, the current is 140-180 amps, the voltage is 23-29 volts, the welding speed is 140-210 mm/min, the molten pool shielding gas flow rate is 15-20 liters/min, duplex stainless steel Argon gas is passed through the tube as the back shielding gas until the end of welding or filling to a thickness of 10mm, and the interlayer temperature is controlled to be ≤150°C;
(4) After the filling welding is completed, the cover welding is carried out, the current is 130-160 amperes, the voltage is 23-27 volts, the welding speed is 170-230 mm/min, and the molten pool protective gas flow rate is 15-20 liters.