Welding Defects With Diagram. For thin plastic sheets welding can be. A the arc is not hot enough for the thickness of the metal b the arc travels too quickly along the joint c the arc is not directed at the parent metal d the weld metal flows ahead of the arc preventing it from impinging on the parent metal.
External welding defects are sometimes visible in naked eyes. A material that is added to clean the surface may also give off a gas to drive away unwanted gases. Fewer weld defects with automatic welding.
The main application of this welding is for lap joint and there are others too.
Internal defects are poor fusion hidden porosity in the deposited metal hidden cracks in the weld and parent metal. Electrode deposit on work. What are examples of discontinuities in fusion welds. Alongside the causes are one or more remedies that can be applied to improve the weld.