Why porosity / porosities often appear in welds?

Why porosity / porosities often appear in welds?

Reason 1: The gas is impure

Porosity – Preventive measures: gas cylinders regularly clean, in the use of gas cylinders inverted 1-2 hours before opening the valve after the water after use.

Reason 2: Surface Oil and rust

Preventive measures: cleaning the surface of the workpiece before welding oil, rust, oxide, etc. . Can be used wire brush, shot blasting and other methods to remove.

Reason 3: Blocked air passage or air leak

Preventive measures: often check the gas system is blocked or gas leakage. Timely cleaning, maintenance or replacement, develop good operating habits.

Reason 4: Seal weld without vent hole

Prevention measures: butt welding will increase chamfer, the middle does not leave air gap. Leave out part of the weld without welding or until the workpiece cools before welding.

Reason 5: Welding Torch angle is too small, air from the rear into the weld pool in the formation of pores.

Prevention measures: adjust the angle of welding torch.

Reason 6: Gas flow is too large or too small

Preventive measures: adjust the flow of protective gas to meet the requirements.

Reason 7: During welding, if the wind speed exceeds 2m/s, the protective gas is blown away, forming nitrogen pores.

Preventive measures: in the case of strong wind welding, to close the doors and windows, indoor welding to add a screen.

Reason 8: The use of non-standard home-made insulation sleeve, long-term use of insulation sleeve in the nozzle combustion, so that CO2 gas decomposition, resulting in pores.

Preventive measures: the use of brand-quality insulation cover.

Reason 9: Nozzle askew installation, conductive nozzle is not in the nozzle center, that is, wire droplet is not in the center of protective atmosphere, how to weld all out of gas hole.

Preventive measures: adjust the position of the nozzle.

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