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

Abstract

A number of innovative technologies are offered in the literature to the purpose of additive manufacturing. Among them, directed metal deposition of wire by means of laser beam is receiving increasing interest since important advantages are benefited in comparison with its powder-based counterpart. Nevertheless, a number of issues must be addressed: this paper aims to provide further understanding of the technology to give grounds to actual applications in an industrial environment. Single trace deposition of Ti-6Al-4V wire over homologous substrate is investigated; the laser power, the processing speed, and the amount of fed metal is changed. The geometrical responses (i.e., trace width, height, depth, shape angle, and dilution) in the cross-section are investigated as a function of the processing parameters. Namely, a global clear view of the responses is given as a function of power and deposited wire mass per unit time. Furthermore, possible occurrence of micro pores is discussed with respect to common international standards. Eventually, an investigation about changes in both the microstructure and the microhardness is addressed: an increase of hardness in the fusion zone is noticed as a consequence of non-diffusional martensitic transformation of the original α-β phases upon rapid cooling, with reduced extent of the heat-affected zone below 0.4 mm.

State of the Art in Directed Energy Deposition: From Additive Manufacturing to Materials Design

“…Additive manufacturing (AM), also popularly known as 3D printing, is at the frontier of development for manufacturing diverse parts and has also been referred to as the third industrial revolution [1][2][3]. AM has an advantage over other conventional manufacturing techniques, making it possible to print complex shapes without the need for several conventional processing steps, such as expensive tooling, dies, or casting molds [3][4][5]. There are several reviews on AM covering different aspects from process dynamics to post-processing [6][7][8][9][10].…”

Directed Energy Deposition (DED) Process: State of the Art

“…Chua et al [203] investigated the influence of the laser power, the travel speed and the bead length on the temperature distribution and the residual stress. Caiazzo [206] derived an equation to estimate the deposition rate of wire. The porosity of the deposited region was considered in the equation [206].…”

“…Caiazzo [206] derived an equation to estimate the deposition rate of wire. The porosity of the deposited region was considered in the equation [206].…”

In situ electro-plastic treatment for thermomechanical processing of CP titanium

“…The controlled atmosphere at high temperatures is necessary to prevent titanium from excessive reactivity with oxygen and hydrogen that causes embrittlement [1,2]. Many research works have been published that suggest alternative cost-effective near net-shaped titanium parts or bulk titanium manufacturing routes, including hybrid and additive manufacturing [3,4]. The hybrid processing method mainly involves powder sintering and post-consolidation treatments [5,6], which inevitably requires a costly and energy-intensive controlled atmosphere.…”