Abstract
Laser welding has been increasingly utilized to manufacture a variety of components thanks to its high quality and speed. For components with complex shapes, the welding position needs be continuously adjusted during laser welding, which makes it necessary to know the effects of the welding position on the quality of the laser welds. In this paper, the weld quality under two (flat and horizontal) welding positions were studied comparatively in the laser welding of Ti6Al4V titanium alloy, in terms of weld profiles, process porosity, and static tensile strengths. Results show that the flat welding position led to better weld profiles, less process porosity than that of the horizontal welding position, which resulted from the different actions of gravity on the molten weld metals and the different escape routes for pores under different welding positions. Although undercuts showed no association with the fracture positions and tensile strengths of the welds, too much porosity in horizontal laser welds led to significant decreases in the strengths and specific elongations of welds. Higher laser powers and travel speeds were recommended, for both flat and horizontal welding positions, to reduce weld porosity and improve mechanical properties.
Highlights
Titanium alloys have been widely used in many industrial fields, such as aerospace and aircraft, because of their superior properties [1]
The cross crosssections sectionsofof ofthe thelaser laser welds produced with the two sets of laser laser welding parameters
It can be seen that, when a lower heat input (2.5 kW, 20 mm/s) was employed, comparable tensile strengths and specific elongations were achieved for flat welds and horizontal welds: these welds fractured through the base metals owing to the higher strengths of the weld metals compared to that of the base metal
Summary
Titanium alloys have been widely used in many industrial fields, such as aerospace and aircraft, because of their superior properties [1]. For components with complex shapes, the weld tracks are generally not straight lines but complicated two-dimensional or three-dimensional curves (e.g., girth welds of pipelines), which lead to changes in the welding positions during laser welding Such changes in welding positions may result in fluctuations in welding quality because of the different actions of gravity for various welding positions, which necessitates the adjustment of welding parameters . Existing research work on positional welding has focused mainly on thick steels used for construction of pipelines, and only a few of them are concerned with laser beam welding Within those references, the laser welding of titanium alloy sheets under different welding positions has not been reported so far. This research sets out to study the influence of two welding positions (flat and horizontal) on the weld quality in terms of weld profile, porosity, and strength, when laser welding Ti6Al4V titanium alloy. The results obtained can be useful in process optimization when laser welding titanium alloy components with complex joint shapes
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