Mechanical properties of Ti-6Al-4V specimens produced by shaped metal deposition

Abstract

Shaped metal deposition is a novel technique to build near net-shape components layer by layer by tungsten inert gas welding. Especially for complex shapes and small quantities, this technique can significantly lower the production cost of components by reducing the buy-to-fly ratio and lead time for production, diminishing final machining and preventing scrap. Tensile testing of Ti-6Al-4V components fabricated by shaped metal deposition shows that the mechanical properties are competitive to material fabricated by conventional techniques. The ultimate tensile strength is between 936 and 1014 MPa, depending on the orientation and location. Tensile testing vertical to the deposition layers reveals ductility between 14 and 21%, whereas testing parallel to the layers gives a ductility between 6 and 11%. Ultimate tensile strength and ductility are inversely related. Heat treatment within the α + β phase field does not change the mechanical properties, but heat treatment within the β phase field increases the ultimate tensile strength and decreases the ductility. The differences in ultimate tensile strength and ductility can be related to the α lath size and orientation of the elongated, prior β grains. The micro-hardness and Young's modulus are similar to conventional Ti-6Al-4V with low oxygen content.

Computational modelling of shaped metal deposition

“…A thermoelastic/perfectly-plastic model was used in the analysis. The tensile deformation curves for this material showed extensive plastic deformation with limited work hardening, therefore validating the application of this model [29]. We remark that solid state phase change effects were neglected.…”

“…However, it should be mentioned that in several cases there is a lack of material parameters at high temperature to correctly represent kinematic hardening. Also, in the SMD process using the Titanium alloy (Ti-6Al-4V) we are analysing in this paper, the tensile deformation curves show extensive plastic deformation with limited work hardening [29]. Therefore, in this case the type of hardening is less relevant to the analysis.…”

Additive manufacturing by means of laser-aided directed metal deposition of titanium wire

“…Other documented researches in this respect are devoted to optimization of the process with conventional heat sources. Tungsten inert gas welding has been shifted to AM [18], the process being valuable for small quantities. Moreover, plasma arc resulted in an overall cost of 15% approximately with respect to laser [19], although unfeasible for thin parts or high-precision applications; hence, a hybrid system to lay Ti-wire metal over parts resulting from powder bed-based AM has been conceived [20].…”

Microstructure characterization of SS308LSi components manufactured by GTAW-based additive manufacturing: shaped metal deposition using pulsed current arc

“…Baufeld et al [2] describe SMD as a novel technique to build net or near net-shaped metal components layer by layer using externally fed metal wire into the melting pool. Yilmaz and Ugla [3] classified the SMD techniques according to the melting heat source into three groups, which are laser beam plus metal wire, electron beam plus metal wire, and arc beam plus metal wire.…”