ND:YAG laser welding of AA6061: Experimental differences between the TEE and LAP joint configurations

Effect of laser welding parameters such as power, out-of-focus length, welding speed and feeding speed on weld properties are studied in tee and lap configurations. Two millimetre thick plates of AA6061 were welded in Tee joint configuration using a cw/Nd:YAG laser and AA5356 wire as the filler metal. The same set-up and wire feeding were used for the lap joining of two millimetre thick square tubing and plates of AA6061. Combination of Taguchi and E.M. design of experiments was carried out to explore efficiently the multidimensional volume of welding parameters, to optimise these parameters and to compare the experimental differences between the two joint configurations. Samples were characterised by optical microscopy, SEM and hardness measurements. The weld properties of interest were weld fillet size, penetration depth, concavity size and heat affected zone dimensions measured by the hardness profiles. The process parameters and their respective and interactive effects on the final responses have been investigated. The results indicate the interlateral relationship between laser process parameters and responses and fundamental differences between the Tee and lap joint laser welding. Difference of hardness profiles between these two configurations highlighted the difference of cooling flows of the two set-up.