Submerged arc welding defects

1.undercut
Undercut Shaorong a recess formed in the weld sides and at the junction of the base metal material, the undercuts so that the weld stress concentration occurs to affect the strength of the weld. 8mm plate butt welds, welding current 750A arc voltage 38V welding speed 34möh, without groove clearance 215mm welding process undercuts after welding. Analysis of the cause of the defect is the welding current is too large, the welding speed is too fast, the welding current is adjusted to 700A, the welding speed is adjusted 32möh Undercuts not generated. If the wire position or angle will produce incorrect Undercuts. Visible by choosing the right welding parameters and process measures to prevent this defect.
2.incomplete fusion
Incomplete fusion welding the weld between the base metal or weld and weld (the multilayer welding) blood is not completely melted binding portion. The dangers of incomplete fusion area type (flaky) similar to the crack, which is a very dangerous defects. Boiler and Pressure Vessel procedures, standard provisions are not allow the presence of incomplete fusion. Lack of fusion generally wire misalignment, resulting in the poor side of the fusion welding partial or weld local bending too much can also cause lack of fusion.
3.slag
Slag refers to the presence of the slag remaining in the weld after welding slag will reduce the strength of the weld metal, poor in the ductility of the weld metal, to withstand fatigue load cases, there may be developed into a crack. Multilayer submerged arc often appear slag defects, which is caused since the interlayer cleaner not clean's. Monolayer submerged arc welding is generally difficult to slag defects.
4.stomatal
Stomata is welded when the bubbles of molten pool in solidification is unable to escape and remnants formed a hole, the presence of pores narrowing the sectional area of the weld metal, and to reduce the strength of the weld metal. The causes may be due to the moisture flux, flux cover thickness improper or flux hopper obstruction. Connector is not clean cleanup also contributed to the cause of the stomata.