Abstract
The present paper shows that laser beam welding of AA6016 aluminum sheets without filler wire but at high feed rates in the order of several tens of m/min is beneficial with respect to depth fluctuation, pores, and centerline cracks. Welds in the overlap configuration with a laser power of 16 kW (cw) at feed rates of 30 m/min and above were investigated. A comparably large laser beam diameter of 630 μm enabled welding at more than 50 m/min without humping. Full penetration and partial penetration welds were accomplished with depths of 2.4 and 2.0 mm, respectively, without pore formation. The partially penetrated welds show negligible local depth fluctuations in the range of only a few μm. Full penetration welds were performed at edge distances of 4, 5, and 6 mm without occurrence of centerline cracks. This constitutes a significant reduction of the critical zone for the formation of centerline cracks at the close edge position compared to conventional laser beam welding parameters.
Highlights
Good weld seams feature no pores and cracks and a constant welding depth
The present paper shows that laser beam welding of AA6016 aluminum sheets without filler wire but at high feed rates in the order of several tens of m/min is beneficial with respect to depth fluctuation, pores, and centerline cracks
The present paper shows that welding at high feed rates, i.e., welding speeds, is beneficial with respect to all three of these requirements
Summary
Good weld seams feature no pores and cracks and a constant welding depth. Meeting these three requirements is known to be very challenging especially in the case of welding of aluminum alloys, without the help of filler wire or any other auxilliaries. The present paper shows that welding at high feed rates, i.e., welding speeds, is beneficial with respect to all three of these requirements. Good weld seams feature no pores and cracks and a constant welding depth Meeting these three requirements is known to be very challenging especially in the case of welding of aluminum alloys, without the help of filler wire or any other auxilliaries.. In the case of laser welding of copper, high laser powers combined with high feed rates have already been found to stabilize the capillary and increase the weld seam quality by reducing pore formation and process fluctuations.. We presume that higher feed rates allow the completion of weld seams with a conventional length of up to 80 mm before the thermal steady state condition establishes and critical thermomechanical loads appear, which initiate the formation of centerline cracks. Apart from increasing the penetration depth, such high laser powers provide the opportunity to weld with very high feed rates. The complete prevention of centerline cracks is achieved at an edge distance of ED 1⁄4 4 mm in the case of full penetration welding of AA6016 sheets
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