Points to note for stainless steel sheet welding
Stainless steel sheet is one of the most commonly used piping products,there are some points you must note to when welding it:
1.Use a power supply with vertical external characteristics, and use positive polarity when direct current (the welding wire is connected to the negative electrode)
2.The shielding gas is argon with a purity of 99.99%. When the welding current is 50~150A, the argon flow is 8~10L/min, when the current is 150~250A, the argon flow is 12~15L/min.
3.The protruding length of the tungsten electrode from the gas nozzle is preferably 4~5mm. It is 2~3mm for fillet welding and other places with poor shielding performance, and 5~6mm for deep grooves. The distance from the nozzle to the work is generally not More than 15mm.
4.In order to prevent the appearance of welding pores, any rust and oil stains on the welding parts must be cleaned up.
5.For welding arc length, 2~4mm is better when welding ordinary steel, and 1~3mm is better when welding stainless steel. If it is too long, the protection effect will not be good.
6.Windproof and ventilation. In windy places, be sure to take measures to block the net, while indoors should take appropriate ventilation measures.
7.In order to prevent the back surface of the bottom weld bead from being oxidized, the back surface also needs to be protected by gas.
8.In order to protect the welding pool with argon gas and facilitate the welding operation, the center line of the tungsten electrode and the workpiece at the welding point should generally maintain an angle of 80~85°, and the angle between the filler wire and the surface of the workpiece should be as small as possible. It is generally about 10°.
Key points and precautions for stainless steel MIG welding
1.Use flat-characteristic welding power source, and use reverse polarity when DC (welding wire is connected to the positive electrode)
2.Generally, pure argon (purity 99.99%) or Ar+2%O2 is used, and the flow rate is 20~25L/min.
3.Arc length, MIG welding of stainless steel is generally welded under the condition of spray transition, and the voltage should be adjusted to the degree of arc length 4~6mm.
4.Windproof. MIG welding is susceptible to wind, and sometimes breeze may cause pores. Therefore, wind-proof measures should be taken where the wind speed is above 0.5m/sec.
Key points and precautions for stainless steel flux cored wire welding
1.Use flat-characteristic welding power source, and adopt reverse polarity when DC welding. Welding can be done with a general CO2 welder, but the pressure of the wire feeder should be loosened slightly.
2.The protective gas is generally carbon dioxide gas, and the gas flow rate is 20-25L/min.
3.The appropriate distance between the welding tip and the workpiece is 15~25mm.
4.Dry elongation, generally about 15mm when the welding current is below 250A, and about 20~25mm when above 250A, is more appropriate.