There are great prospects for utilizing multipass laser hot-wire welding to join thick steel sheets, especially for techniques commonly performed in single passes, e.g., laser arc hybrid welding, fall short, presenting great opportunities for vehicle industries and offshore applications. Many modern approaches for applying these techniques rely on customized wire feeding nozzles or special scanner optics to ensure proper laser–wire interactions and, in turn, robust process behavior, making them less accessible to many industries. Here, we present a modified adaption of laser hot-wire welding, utilizing more readily available equipment, including an unmodified welding source and a nozzle, presented and evaluated through means of, e.g., high speed imaging and macroscopy. This technique was found to have high process robustness, especially for sealing passes, if wire resistance heating is kept within suitable levels. It is able to both maintain proper laser–wire interaction and produce close to net-shape weld caps. Also, recommended process parameters are presented, together with a description of a potential method for suppressing solidification cracking.
In order to lead to a competitive advantage there is the need to carefully consider the pros and cons of state of the art manufacturing techniques. This is frequently carried out in a competitive manner but can also be done in a complementary way. This complementary approach is often used for the processing of difficult-to-machine materials with particular regard to high tech parts or components. Hybrid machining processes (HMPs) or -more general -advanced machining processes (AMPs) can be brought to the point that the results would not be possible with the individual constituent processes in isolation [1]. Hence, the controlled interaction of process mechanisms and/or energy sources is frequently applied for a significant increase of the process performance [2] and will be addressed within the present paper.A via Electron Beam Melting (EBM) manufactured gamma titanium aluminide (γ-TiAl) nozzle is extended and adapted. This is done via hybrid Laser Metal Deposition (LMD). The presented approach considers critical impacts like processing temperatures, temperature gradients and solidification conditions with particular regard to crucial material properties like the phenomena of lamellar interface cracking [3][4].Furthermore, selected destructive and non-destructive testing is performed in order to prove the material properties. Finally, the results will be evaluated. This will also be done in the perspective of other applications.
Additive manufacturing (AM) can be used for the fabrication of large metal parts, e.g., aerospace/space applications. Wire arc additive manufacturing (WAAM) can be a suitable process for this due to its high deposition rates and relatively low equipment and operation costs. In WAAM, an electrical arc is used as a heat source and the material is supplied in the form of a metal wire. A known disadvantage of the process is the comparably low dimensional accuracy. This is usually compensated by generating larger structures than desired and machining away excess materials. So far, using combinations of arc in atmospheric conditions with high precision laser heat sources for AM has not yet been widely researched. Properties of the comparable cheap arc-based process, such as melt pool stability and dimensional accuracy, can be improved with the addition of a laser source. Within this paper, impacts of adding a laser beam to the WAAM process are presented. Differences between having the beam in a leading or a trailing position, relative to the wire and arc, are also revealed. Structures generated using the arc-laser-hybrid processes are compared to ones made using only an arc as the heat source. Both geometrical and material aspects are studied to determine the influences of laser hybridization, applied techniques including x ray, energy-dispersive X-ray spectroscopy, and high precision 3D scanning. A trailing laser beam is found to best improve topological capabilities of WAAM. Having a leading laser beam, on the other hand, is shown to affect cold metal transfer synergy behavior, promoting higher deposition rates but decreasing topological accuracy.
Purpose The steadily growing popularity of additive manufacturing (AM) increases the demand for understanding fundamental behaviors of these processes. High-speed imaging (HSI) can be a useful tool to observe these behaviors, but many studies only present qualitative analysis. The purpose of this paper is to propose an algorithm-assisted method as an intermediate to rapidly quantify data from HSI. Here, the method is used to study melt pool surface profile movement in a cold metal transfer-based (CMT-based) AM process, and how it changes when the process is augmented with a laser beam. Design/methodology/approach Single-track wide walls are generated in multiple layers using only CMT, CMT with leading and with trailing laser beam while observing the processes using HSI. The studied features are manually traced in multiple HSI frames. Algorithms are then used for sorting measurement points and generating feature curves for easier comparison. Findings Using this method, it is found that the fluctuation of the melt surface in the chosen CMT AM process can be reduced by more than 35 per cent with the addition of a laser beam trailing behind the arc. This indicates that arc and laser can be a viable combination for AM. Originality/value The suggested quantification method was used successfully for the laser-arc hybrid process and can also be applied for studies of many other AM processes where HSI is implemented. This can help fortify and expand the understanding of many phenomena in AM that were previously too difficult to measure.
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