A welder is running GMAW outdoors in a steady breeze and the beads are full of surface pinholes. What is the most likely cause?
- The travel speed is too slow for the wire feed speed
- The wire has too much silicon and manganese in it
- The shielding gas is being blown away from the arc
- The work lead is clamped too close to the weld
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C. The shielding gas is being blown away from the arc
Wind strips the shielding gas from the puddle so air reaches the molten metal and gas is trapped as porosity. Wind screens, or a process that does not rely on external gas, are the cure. Deoxidizers in the wire reduce porosity; they do not cause it.
Reference: Weld discontinuities: causes of porosity
Which welding condition is a common cause of undercut?
- Amperage too low with a short arc
- Travel speed too slow on a flat weld
- Electrode kept in a holding oven
- Amperage too high with a long arc
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D. Amperage too high with a long arc
Excessive current, a long arc, fast travel and a poor electrode angle melt away the plate edge faster than filler metal can fill it. Low amperage and slow travel tend to give overlap and poor fusion instead.
Reference: Weld discontinuities: causes of undercut
Weld metal that rolls out over the base metal at the toe without fusing to it is called what?
- Undercut
- Overlap
- Spatter
- Convexity
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B. Overlap
Overlap (often called cold lap) is weld metal protruding beyond the toe that lies on the surface unfused, leaving a sharp notch. It usually comes from travel that is too slow or heat that is too low. Excess convexity is a profile problem but the weld is still fused at the toe.
Reference: Weld discontinuities: overlap