Anisotropy of stress-strain behavior, fracture toughness, and fatigue crack growth rate was studied for Inconel 738LC alloy built by the Dynamic Metal Deposition technique (3DMD, a high-speed Directed Energy Deposition technique). The measured quasi-static properties, i.e. stress-strain and fracture toughness showed only subtle anisotropy, with no more than 10% differences found for different orientations. The fatigue crack growth rate was influenced by the specimen orientation more significantly (30% for fatigue crack growth threshold, up to 90% for Paris exponent and coefficient). This pilot study attributes the anisotropy of fatigue crack growth properties to material texture and the columnar grain geometry resulting from directional solidification. The obtained testing results indicate that 3DMD technology can produce materials with good mechanical and fracture properties even from materials considered as non-weldable such as In 738LC. The study provides a solid experimental base for further investigation of the fatigue crack growth mechanism relation to the material texture in 3DMD In 738LC.

Laser cladding or metal deposition (LMD/DED) is widely used for wear-resistant coatings, repair and additive manufacturing applications due to the excellent properties of the deposited material. However, processes on complex 3D surfaces are often a challenge because they require time-consuming programming. This is particularly the case when no CAD data is available for the parts on which metal coatings or structures have to be applied. As a solution, we describe a digital process chain that begins with a 3D scanning process within the laser cladding machine (either robotic or CNC type). Using special software, high-quality 3D models of the scanned parts are created. For coating applications, these models are visualized on a PC. The operator can define cladding areas with just a few clicks of the mouse. Based on predefined parameters, powerful software calculates all the required tool paths. An additional simulation step can be used to verify collision-free operation. Finally, robot or CNC programs are automatically generated that can be executed immediately. Similar software is used to create 3D parts directly from CAD files. Finally, by combining both approaches, 3D geometries can be printed directly onto existing 3D freeform parts using laser metal deposition/LMD, even if their shape is arbitrary and not well documented by CAD data.

Additive Manufacturing processes such as laser metal deposition (LMD) are often used in repairing processes where material is deposited onto existing components. During the LMD process, thermal stresses and deformations of the substrate can occur. This deformation results from a multitude of effects throughout the manufacturing process. To precisely measure the time-temperature-deformation history, an experimental setup combining in situ deformation measurement and thermography is conceived. 3D deformations are measured using a stereo camera system observing a stochastically distributed speckle pattern applied on the surface of the substrate. Additionally, the temperature is measured on the underside of the substrate by means of thermal camera. Material is applied using LMD on the opposite side of the measurement therefore there is no chance of the laser beam interfering with the optical measurement of temperature and deformation or damaging the measurement equipment. Due to the areal nature of the measurement system chosen, it is possible to achieve high temporal and spatial resolution to identify critical heat distributions and welding path strategies, which lead to deformation. This work proposes a novel measurement setup and provides possible use cases for optimizing path planning during additive manufacturing processes based on three exemplary path geometries.

In the field of additive manufacturing, the demand for Extreme High-Speed Laser Material Deposition (EHLA) is increasing due to its unique process characteristics, economic efficiency as well as its great resource efficiency. The process is currently mostly used for surface functionalization through coating, by means of corrosion and wear protection. Thereby, almost all materials can be processed and nearly all material combinations can be created. The layers produced are dense and metallurgical bonded, and furthermore the surface roughness produced is low, so that only 20-100 μm has to be removed to produce a finished surface. However, it can also be used for the generation of 3D geometries. The greatest cost factor in the production is the coating material. With increasing requirements, for example in wear protection, cost-intensive special alloys or materials must be used. An opportunity to increase the areas of application in the field of wear resistance as well as increasing material efficiency is offered by combining EHLA with the innovative post-processing methods of hammering, solid as well as smooth rolling. Using these processes, the surface roughness can be reduced to a value of Rz 1-3 μm on the one hand and the surface hardness can be increased on the other hand. The hammering and solid rolling processes differ in their depth of impact. In the case of hammering, the impact depth can be a few millimeters and in the case of solid rolling only a few tenths of a millimeter. So far, the influence of hammering or solid rolling of additive manufactured volumes or surfaces has not been investigated. In the context of this study, the influence of hammering and solid rolling on a volume produced with EHLA is investigated. For this purpose, an EHLA produced volume of IN718 is built up and the influence of hammering as well as solid rolling on the surface roughness and hardness is analyzed.

In the past few years, the Extreme High-Speed Laser Material Deposition (EHLA) process has been used as a coating technology alongside conventional processes due to its unique process characteristics and is an economical and sustainable alternative to traditional technologies. The essential characteristic of the process is that the main energy is absorbed by the powder particles so that they reach the substrate surface in a molten state. Thereby, metallurgically bonded and dense wear and corrosion protection coatings are generated. This leads to significantly higher surface and deposition rates can be achieved in comparison to Laser Material Deposition (LMD), and heat-sensitive substrates can be coated. Moreover, in addition to this resource efficiency, the process is not only economically attractive but also sustainable. To reduce component weights as well as secondary energy consumption, aluminium has become an essential base material in most industrial sectors. Aluminium is not simple to process and the wear resistance is small due to the low hardness in comparison to widely used steels. Various technology solutions are currently being investigated for the coating of aluminium. The low melting temperature of aluminium (approx. 750 °C) poses a great challenge when coating with, for example, iron-based alloys. Another challenge for laser-based systems is the reflectance of aluminium in the wavelength range approx. between 1030-1070 nm of conventional laser beam sources. The high degree of reflection of aluminium is the reason why additive processing quiet challenging is. Therefore, for conventional laser-based processes, laser beam sources in other wavelength spectra, e.g. green or blue, are being developed to improve the processing of aluminium. Currently, commercially available multi-kW lasers in the visible light spectrum are still below the available power of IR beam sources. In the context of this study, the feasibility of coating aluminium using EHLA is investigated. A high power 8 kW IR disk laser of the TRUMPF company is used to determine the maximum possible deposition and surface rate.

This work investigates the effect of processing parameters on the microstructure and composition of Ni-base alloys produced by laser forming, an additive technique also known as direct metal deposition. The parameters assessed in the study include powder flow rate, traverse speed, laser power, and spot size. In all experiments, a melt pool diameter of 0.3 mm was maintained. The results show that laser formed alloys are similar in structure to conventional wrought alloys with additional peaks formed as a result of the oxidation of active alloying elements. The complex compounds observed on the surface of the laser formed samples disappeared after polishing. Paper includes a German-language abstract.