Abstract
The effect of direction of unidirectional pores on the fusion zone shape, which produced by laser welding, of lotus-type porous iron was investigated through the numerical simulation of temperature distribution. Three-dimensional heat-transfer analyses, which take into account the thermal properties of the lotus-type porous iron depending on the direction and volume fraction of unidirectional pores, were performed by the ABAQUS FE code with user-defined subroutines. These results indicated that the lotus-type porous iron has little anisotropy of melting property. The calculated shape of weld fusion zone is in good agreement with the cross-sectional view obtained by experiments. In order to clarify the reason of these results, anisotropy of thermal diffusivity in the lotus-type porous copper, magnesium, and iron used and anisotropy of laser energy absorption coefficient for these metals were estimated. As a result, the lotus-type porous iron used has a little difference of thermal diffusivity and laser energy absorption coefficient due to its low thermal conductivity, low porosity, large average pore diameters, and high laser absorption coefficient of base metal.
