The paper investigates the fabrication of Selective Laser Melting (SLM) titanium alloy Ti6Al4V micro-lattice structures for the production of lightweight components. Specifically, the pillar textile unit cell is used as base lattice structure and alternative lattice topologies including reinforcing vertical bars are also considered. Detailed characterizations of dimensional accuracy, surface roughness, and micro-hardness are performed. In addition, compression tests are carried out in order to evaluate the mechanical strength and the energy absorbed per unit mass of the lattice truss specimens made by SLM. The built structures have a relative density ranging between 0.2234 and 0.5822. An optimization procedure is implemented via the method of Taguchi to identify the optimal geometric configuration which maximizes peak strength and energy absorbed per unit mass.

Directed metal deposition by means of laser beam is investigated in this article. The process is receiving increasingly interest in the frame of additive manufacturing to the purpose of maintenance, repair and overhaul of condemned products when severe conditions hindering the working order have been experienced. Minimal distortion, reduced heataffected zones and better surface quality are benefited in comparison with conventional techniques. Namely, metal feeding of 2024 aluminium powder is considered to produce clad traces on 2024 aluminium plates, aiming to give grounds for repairing damaged real components using materials with same or similar features with respect to the parent metal. A fibre-delivered disc laser and a three-way feeding nozzle are used. The responses are discussed in terms of geometry, microstructure and microhardness both in the fusion zone and in the heat-affected zone; the optimization is conducted via desirability functions, based on proper technical constraints upon numerical modelling. Reparation of real parts, where cracks are machined to produce V-grooves to be filled, is aimed.

Optimization of processing parameters and exposure strategies is usually performed in additive manufacturing to set up the process; nevertheless, standards for roughness may not be evenly matched on a single complex part, since surface features depend on the building direction of the part. This paper aims to evaluate post processing treating via laser surface modification by means of scanning optics and beam wobbling to process metal parts resulting from selective laser melting of stainless steel in order to improve surface topography. The results are discussed in terms of roughness, geometry of the fusion zone in the cross-section, microstructural modification, and microhardness so as to assess the effects of laser post processing. The benefits of beam wobbling over linear scanning processing are shown, as heat effects in the base metal are proven to be lower.

This article aims to use the methodology of dimensional analysis to determine the influence of process parameters in selective laser melting of metal powders. The complexity of the selective laser melting process, in fact, does not allow a full evaluation of a physical model, involving all the influencing variables. Through dimensional analysis, the article intends to find out an appropriate definition of a set of non-dimensional groups in order to represent the output parameters. The article, therefore, focuses on the impact of the most influential ones, referring to the production of samples made of Ti–6Al–4V powder using a laser sintering machine EOSINT M270. Specimens are examined in terms of their relative density, given its importance in the design and production of elements for dental implants. Adequate exposure strategies based on the results provided may allow careful designs in order to provide tailored porosity to enhance biological fixation and achieve long-term stability.

Laser welding has been proven to be promising for aerospace. Welds with high aspect ratio are produced with lower heat input compared with conventional arc-welding processes; furthermore, higher productivity and lower distortion are benefited. Nevertheless, specific issues must be addressed depending on the material to be welded. In this frame, laser welding of AA 2024 in T3 heat treatment condition, which is among the most common light metal alloys in aerospace, is discussed. A comprehensive review of issues influencing weldability is given, combining ad-hoc trials with Yb:YAG disk-laser source and existing knowledge in the referred literature. Therefore, a number of subjects are investigated: the need for proper gas assistance, the threshold value of irradiance to be overcome for key-holing as a consequence of low absorptance and high conductivity, magnesium vaporization leading to instability and macro-pore formation, softening in the fused zone resulting in lower strength due to dissolution of precipitates and loss of the strengthening phase. EDS inspections, Vickers micro-hardness tests and tensile tests have been conducted to discuss the response. Convincing results have been achieved both in terms of reduction of the heat affected zone and ultimate tensile strength, in comparison with other findings in the literature.