What are Welding-defects?

Another cause is the use of a very wide weld joint. If the arc is directed down the center of the joint, themolten weld metal will only flow and cast against the side walls of the base plate without melting them. Theheat of the arc must be used to melt the base plate. This is accomplished by making the joint narrower or bydirecting the arc towards the side wall of the base plate. When multipass welding thick material, a split beadtechnique should be used whenever possible after the root passes. Large weld beads bridging the entiregap must be avoided.

They are excessive conditions, outside the acceptance limits, which risks to compromise the stability or the functionality of the welded structure. They are also called rejectable discontinuities. This means that the same type of discontinuity of a lesser degree, might be considered harmless and acceptable.

Are there acceptable Welding-defects? No, by definition a defect is rejectable. There can be acceptable discontinuities. The designer, or the purchaser, or the person in charge of the welding project is entitled to define the limits of acceptance. And these limits are valid only for the application and the usage involved.

Are there undetected defects? Hopefully not! No Welding-defects should go undetected, but undetectable discontinuities yes, that are acceptable, as defined by the designer.

What should be done when Welding-defects are detected? One shouldreject the items and put them temporarily on hold. One should determine the cause and try to implement a corrective action to avoid future recurrence. Then an authorized professional should determine if the defects are repairable or not. If yes by which procedure. Standard procedures may be approved for routine application.

Lack of fusion can also occur in the form of a rolled over bead crown. Again, it is generally caused by a verylow travel speed and attempting to make too large a weld in a single pass. However, it is also very oftencaused by too low a welding voltage. As a result, the wetting of the bead will be poor.When welding aluminum, the common cause of this type of defect is the presence of aluminum oxide. Thisoxide is a refractory with a melting point of approximately 3500⁰F (1927⁰C). It is also insoluble in moltenaluminum. If this oxide is present on the surfaces to be welded, fusion with the weld metal will be hampered.

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