Improvement of hardness of aluminium AA1200 by laser surface alloying

Abstract

Aluminium is vastly used in industry due to its low cost, light weight and excellent workability, but lacks in wear resistance and hardness. Laser alloying is used to improve the surface properties such as hardness by modifying the composition and microstructure of the surface without affecting the bulk properties of the materiaL. The process involves melting the substrate surface and injecting the powder of the alloying material into the melt pool. Process parameters such as laser power, beam spot size, laser scan speed and powder feed rate have to be controlled to achieve the desired surface properties. In this investigation the surface of aluminium AA 1200 was laser alloyed using a 4.4kW Rofin Sinar Nd:YAG laser to improve its hardness and wear resistance. The alloying was performed with different Ni, Ti and SiC powder weight ratios at 10mm/s laser scanning speed. The powder feed rate was 2-3g/min depending on the powder composition. The laser spot size was 4mm. The shielding gas used was argon at a flow rate of 4L/min.