Understanding the wire electrical discharge machining of Ti6Al4V alloy

Abstract

Non-conventional machining process for instance, wire electrical discharge machining (WEDM) of titanium alloys is gaining attention due to non-contact nature of this process. To deepen the understanding in this area, this study investigates surface generation, kerf width, discharge gap, material removal rate and wire degradation during WEDM of Ti6Al4V alloy. Pulse on time (4–10 μs), flushing pressure (7–18 MPa) and wire tension (800–1700 gf) were varied and resulting influences on output parameters were analysed. It was found that, machined surfaces consist of multi-layered recast layer with the presence of cracks, holes as well as traces of materials from electrode wire. The composition and roughness of the machined surface varies slightly with respect to machining condition without following any trend. In addition, deformation and morphology of deformed wire electrode after the WEDM process was also reported in this study.

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“…Conversely, after mWEDM surface treatment, the surface morphology was completely transformed. The top surface of mWEDMed γ-TiAl consists of the crater, rippled surface, a number of cavities and overlapping craters similar to what has been previously reported by others [27,28]. In WEDM method, individual wire electrical discharges cause the removal of microparticles of the material.…”

“…Chemical analysis of the recast layer (Region A) and subsurface area under the recast layer (Region B) indicated the presence of Ti, Al, O, Cu, Nb, and Cr. The presence of Cu in the recast layer is due to ion transfer from the brass wire electrode which has been previously reported by other researchers [24,27,28]. The presence of the oxygen for oxides produced by mWEDM as compared with the original γ-TiAl substrate can be attributed to preferential oxidation of Ti which is thermodynamically favored [35].…”

“…Sample H presented less irregularity with some peaks and valleys than was achieved with other samples. Samples after mWEDM and laser treatment exhibit a more diversified surface topography with sharp peaks compared with other samples [26,27]. It is worth adding that the interaction between the acid and γ-TiAl substrate after sandblasting caused a slight smoothing of the surface.…”

“…Discharged material particles are subsequently carried away from the cut area by a flushing jet of dielectric liquid. In this way, a great number of craters are formed on the surface [27]. Moreover, micro-cracks are present on mWEDM modified surfaces, which were likely formed due to thermal stresses [28].…”

Investigation of wire electrical discharge machining modes influences on crack formation and surface layer morphology of the Ti-6Al-2.5Mo-2Cr-0.3Si titanium alloy

“…В исследованиях [9][10][11] показано, что значения параметров микрорельефа и величины их отклонений становятся больше с ростом пикового тока и длительности импульса. Установлено, что короткий импульс (4-6 мкс) обеспечивает более низкие значения параметров микрорельефа, а давление прокачки и натяжение проволоки не оказывают влияния на точность и качество обработки поверхности [12].…”