Abstract: The authors found that for various austenitic alloys the two-dimensional equiaxed dendrites grown in the center of welding arc crater have similar patterns.The scanning electron microscopic images further revealed the actual micro-pattern of the two-dimensional equiaxed dendrites.Some bases for fractographic analysis of solidification cracks were provided.As a result of crystallographic analysis,a new point of view was proposed by the authors that the two-dimentional equiaxed dendrites in welding arc crater for fully austenitic alloys were of laminate structure comprising four symmetric screw dislocations of reverse signs.