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SOLUTIONS: Evaluation of welds Typical welding faults Unmelted edge

Bead crown too high Undercut Crack

Poor fusion Embedded slag Pores

Root fault

2.10

Root faults

When laying the first bead along the root in a butt joint, penetration at the root may be irregular or insufficient. When current is excessive, penetration will be too high. Insufficient penetration may be due to the current setting being too low, or the rate of travel too high. The electrode may also be too large for the groove to be welded.

Fusion faults

If the current is too low or rate of travel too high, fusion faults may result, i.e. insufficient melting and fusion between the filler and the base metal.

Fusion faults may also occur if a small electrode is used on a large area of cold base material. A larger electrode diameter should be used, and the base material preheated.

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Bead edge defects

Bead edge irregularities can occur if current output is too high. Bead edge faults may also occur at correct current output if the arc is too long or if electrode movement is incorrect. When welding upwards on a vertical plane and using a weaving movement, the electrode should be momentarily held still at each side of the bead to obtain good penetration and avoid edge defects. Edge faults and undercut may act as fracture indicators in the welded connection.

Pores

Pores in the weld may be due to moisture content in the electrode coating, especially when welding with basic electrodes. Pores in the weld may also arise if the base material to be welded is wet or damp. Other reasons can be because of to long an arc, allowing air into the weld zone. A porous weld will have reduced strength properties.