EFFECT OF LASER SURFACE TREATMENT ON THE QUALITY OF MICROSTRUCTUREIN RECYCLED Al-Zn-Si CAST ALLOY

Recycled Al-Zn-Si casting alloys can often be used in new cast products for mechanical engineering, in hydraulic castings, textile machinery parts, cable car components or big parts without heat treatment. Improved mechanical properties and favourable of recycled microstructure of Al-alloys can often significantly increase the lifetime of casting and reduce costs for fuel and reduction of environmental loading. The paper is focused on using one of possible technologies that provide increased mechanical properties of recycled aluminium cast alloys for automotive industry, and that is laser surface hardening. For study was used recycled AlZn10Si8Mg cast alloy. The effect of laser beam Nd: YAG lasers BLS 720 was evaluated with the laser power 50 W and 80 W on the surface of samples. The final microstructure of aluminium alloys depend on the laser process parameters. The changes of microstructure as a grain refinement of the microstructure after laser surface hardening was observed by using classical techniques of etching and deep etching with concentrated HCl. Microstructure was evaluated on an optical microscope Neophot 32 and SEM.