Abstract
In this paper, two-dimensional thermal and structural analyses at heat-affected zone (HAZ) of the laser weldment of Inconel 718 alloy were carried out by the finite element code, ANSYS to make clear the mechanism of liquation crack from a mechanical standpoint.
According to the heat transfer analysis, the width of liquefied temperature range at the neck region of nail head type penetration of weld bead was larger than that at other regions. This is the cause that liquation crack easily occurred at the neck region of weld bead.
Moreover, as a result of structural analysis, both the equivalent plastic strain and the first principal plastic strain at the elevated temperature concentrated at the neck region of weld bead. These strains increased with an increase in welding speed and with a decrease of the radius of curvature at the neck region of weld bead. On the other hand, the occurrence of liquation crack also depended on welding speed and the radius of curvature at the neck region of weld bead, and thus depended on the elevated temperature strain at HAZ.
It was followed by structural analysis that the elevated temperature strain should be utilized as a parameter for estimation of occurrence of liquation crack.
