HIGH-POWER ND-YAG LASER-WELDING OF SIC PARTICLE-REINFORCED ALUMINUM-ALLOY-2124

The effects of different Nd-YAG laser output waveforms on the weldabil ity of a SiC particle reinforced aluminium alloy 2124 have been studie d. The results show that although the square waveform can produce the greatest depth-of-penetration among the three different waveforms stud ied, i.e. continuous wave, sine wave and square wave, a high level of porosity was observed in the weld. Alternatively, porosity free welds with a reasonable depth-of-penetration can be obtained by using a sine waveform operated at high peak powers. However, the results also show that it would be difficult to stop the formation of aluminium carbide s entirely in the fusion zone simply by varying the laser output param eters and the waveform. In order to stop the formation of carbides, a new laser joining technique has been developed. This involved brush pl ating of nickel on the joining surfaces before laser welding. The resu lts of the corrosion tests of the weld zone show that welding with a n ickel coating would results in a much lower corrosion current than tha t without nickel coating.