Radial cracks formed in weld craters as the weld pool solidifies and shrinks. They are caused by low melting constituents which are segregated in the pool during solidification and cause the metal to tear due to shrinkage stresses. When possible, they should be eliminated by allowing the arc to dwell in the crater for a short time instead of removing the electrode
quickly. In this way, the crater can fill up and reduce the shrinkage forces. Also helpful with gas tungsten arc welding (GTAW) is a technique which allows the current to decay slowly at the end of a weld to reduce the solidification rate.
