1990 Volume 8 Issue 2 Pages 179-185
In deep penetration electron beam welds, some characteristic defects such as porosity and solidification crack have been occurred depending on the occurrence of the locally delayed solidification pattern. In this report, some dominant factors affected on the delayed solidification have been investigated.
The results obtained were as follows.
(1) The delayed solidification was resulted from remelting or secondary melting effect of the solidified wall by the stagnated molten metal in a beam cavity.
(2) The amount of the stagnated molten metal depended on how easily the molten metal flowed out of the beam cavity.
(3) Strong evaporation near the root promoted the smooth flow of molten metal, reslting in suppressing the delayed solidification.
(4) Gases involved in the base metal and evaporation from the front wall of the cavity perturbed the molten metal flow, resulting in promoting the delayed solidification.