Crater cracks may take the form of a single crack or starshaped cracks and will usually be found:

by magnetic particle techniques since crater cracks are always subsurface.

anywhere along a weld where the welding was stopped and restarted.

in the natural crater formed between the two plates in a typical fillet wel

in the root area of a multiple-pass weld where the weld metal failed to flow completely into the root opening.