Characterization of fiber laser welding of Ti6Al4V by welding common joint types

Abstract This work deals with the Ti6Al4V welding which is used in many fields such as in aerospace, offshore, automotive and medical applications due to its properties and there is an increase in the demand for Ti6Al4V as a titanium alloy. Due to production difficulties it has a high raw metal cost while also owing to its properties the machining processes face complications too. Therefore welding technology has been applied to reduce raw material waste and machining to obtain the desired form. By welding it is possible to weld sheets or plates together to produce a new part without performing all the processes by machining and waste a lot of material. But in the welding another aspect rises up which is weld quality and whether it is possible to reach the same kind of requested traits as the machined part or not. Therefore a study on Ti6Al4V welding has been performed by use of 1KW Fiber laser source. Through the experiment three different configurations or sheet arrangements have been studied for welding, a Lap-joint, an L-joint and an angular or fillet joint. In order to perform the welding a clamping system and a shielding system are needed. The clamping system is needed to fix the configurations in place and prevent dislocations of the welding parts while are being welded. The shielding system is needed to provide shielding gas to the weld and just welded area to avoid oxidation which titanium is prone to produce at high temperature. In consequence these two systems have been designed and produced to fulfill the welding procedure requirements. Then the configurations have been welded in different velocity ranges while the other parameters have been kept on a fixed level. Among these three configurations the first two including the Lap-joint and L-joint have been studied for metallurgical analysis in three sections, two cross sections and one longitudinal while the last configuration has been analyzed only in the cross sections due to the difficulties regarding the cut of angular-joint longitudinal cross section in the middle of the weld. The welds’ width, penetration and porosities have been measured for Lap and L-joints whereas for Angular-joint the fusion length, penetration and porosities have been measured. According to the obtained results the penetration depth and welds’ width increase slightly with the decrease in velocity while it seems that the porosity ratio in the fusion zone area of welds is not a function of welding speed. Also it is noted that the welds width and penetration depth slightly increase too along the welding line, in such a way that the sections at the end line of the weld have higher values in respect to the sections in the beginning of the weld line.