Focusing on laser additive manufacturing techniques for turbo‐engine applications, two major european and german funded projects, FANTASIA and TurPro, are presented. The aim of both projects is to contribute to winning global leadership of european turbo‐engine manufacturers by developing new flexible and near‐net‐shape additive manufacturing chains and repair techniques based on Laser Metal Deposition (LMD), as seen in Figure 1 and selective Laser Melting (SLM). This article reviews the status quo of FANTASIA and TurPro.

Laser metal deposition (LMD) is one of the most important laser additive manufacturing processes. It can be used to produce functional coatings, to repair damaged parts and to manufacture metal components. Ti6Al4V is one of the most commonly used titanium alloys, since it features a good balance of the mechanical properties of strength and ductility. The LMD of Ti6Al4V is attracting more and more attention from both science and engineering. The interest in processing Ti6Al4V with LMD in industry, especially in aerospace and medical branches, has been increasing in the last few years. In this paper, the state of the art for LMD of Ti6Al4V is reviewed. In the first part, the basics for Ti6Al4V, including, for example, the development history, the material properties, the applications, the crystal structure, the heat treatment and the mechanical properties, are introduced. In the second part, the main emphasis is on state of the art for LMD of Ti6Al4V. Initially, the process parameters of the current state of the art in the last years and their effects are summarized. After that, the typical microstructure after LMD is discussed. Then, the conducted heat treatment methods and the achievable mechanical properties are presented. In the end, some of the existing, current challenges are mentioned, and the possible research directions for the future are proposed.

For the purpose of improving the productivity of laser metal deposition (LMD), the focus of current research is set on increasing the deposition rate, in order to develop high-deposition-rate LMD (HDR-LMD). The presented work studies the effects of the powder stream on HDR-LMD with Inconel 718. Experiments have been designed and conducted by using different powder feeding nozzles—a three-jet and a coaxial powder feeding nozzle—since the powder stream is mainly determined by the geometry of the powder feeding nozzle. After the deposition trials, metallographic analysis of the samples has been performed. The laser intensity distribution (LID) and the powder stream intensity distribution (PID) have been characterized, based on which the processes have been simulated. Finally, for verifying and correcting the used models for the simulation, the simulated results have been compared with the experimental results. Through the conducted work, suitable boundary conditions for simulating the process with different powder streams has been determined, and the effects of the powder stream on the process have also been determined. For a LMD process with a three-jet nozzle a substantial part of the powder particles that hit the melt pool surface are rebounded; for a LMD process with a coaxial nozzle almost all the particles are caught in the melt pool. This is due to the different particle velocities achieved with the two different nozzles. Moreover, the powder stream affects the heat exchange between the heated particles and the melt pool: a surface boundary condition applies for a powder stream with lower particle velocities, in the experiment provided by a three-jet nozzle, and a volumetric boundary condition applies for a powder stream with higher particle velocities, provided by a coaxial nozzle.

A variant of conventional laser material deposition (LMD), extreme high-speed laser material deposition (German acronym: EHLA) is characterized by elevated process speeds of up to 200 m/min, increased cooling rates, and a significantly reduced heat affected zone. This study focuses on the feasibility of using EHLA to apply material onto Fe-based substrate materials with AISI 4340 as a filler material. We studied how three different build-up strategies—consisting of one, three, and five consecutive deposited layers and hence, different thermal evolutions of the build-up volume—influence the metallurgical characteristics such as microstructure, porosity, hardness, and static mechanical properties. We propose a thermo-metallurgical scheme to help understand the effects of the build-up strategy and the thermal evolution on the microstructure and hardness. The tensile strength of the build-up volume was determined and is higher than the ones of forged AISI 4340 material.

The aim of this study is to characterize microstructures and tensile properties of Inconel 718 (IN718) formed by high deposition-rate laser metal deposition (LMD), and furthermore to verify that the properties of the material are equivalent to those obtained by conventional manufacturing processes, such as casting and forging, and therefore satisfy the specifications for industrial applications. Initially, the powdery additive was characterized in terms of chemical composition, morphology, and porosity. Afterward, blocks for producing tensile specimens were deposited by applying the newly developed high deposition-rate LMD process that has a deposition rate of approximately 2 kg/h. Finally, microstructures and tensile properties of directly deposited and heat-treated material were analyzed, respectively. From the results, precipitation of an irregular shaped phase, which is believed to be Laves phase, and segregation of Nb and Mo were found at interdendritic regions of the directly deposited material. The directly deposited material exhibited relative low tensile strength and 0.2% yield strength but high elongation. Moreover, due to recrystallization that occurred in heat treatment, columnar grains in the directly deposited material transformed to equiaxed grains. By heat treatment, Laves phase was dissolved, and three extra phases, which are believed to be δ phase, strength phases γ′ and γ″, were precipitated. After heat treatment, tensile strength and 0.2% yield strength of the material were significantly enhanced, whereas the plastic elongation decreased by approximately 38%. In comparison to conventional manufacturing technology, the heat-treated IN718 presented superior tensile strength, 0.2% yield strength, and plastic elongation to aerospace material specifications for casted and wrought IN718.