Thermal and morphological analysis of the interaction effect of different assist gases with gas-filled closed-cell aluminium foam during laser cutting process

Closed-cell aluminium foam, a porous structure, is effectively used for insulation, structural applications, packaging and filtering. Cutting of aluminium foam with the help of fibre laser is an efficient method due to the inherent advantages of fibre laser. Laser cutting of aluminium foam was carried out using a 2-kW fibre laser system for varying process parameters and different assist gas environments. Use of different foaming agents results in the generation of gas-filled pores. During the laser cutting process, the interaction of these gas-filled pores with assist gas results in in-situ reactions, generating different kerf quality. This interaction effect of foam cutting was reported using optical, metallurgical and thermal analysis. Thermal cycles were recorded to understand the occurrence of different in-situ reactions. From the temperature signal for different assist gases, oxygen showed the highest temperature, followed by nitrogen and argon. Argon assist gas gave minimum kerf width, while nitrogen assist gas produced minimum dross. Elemental and phase analysis showed the presence of new compounds and intermetallics in the cut section that stipulated the occurrence of in-situ reactions during the cutting process. The internal pore surface showed the presence of spatter in case of oxygen, while nitrogen and argon gas environment showed relatively less pore-clogging.