A Comparative Evaluation of Powder Characteristics of Recycled Material from Bronze Grinding Chips for Additive Manufacturing.

In the manufacturing process of ship propellers, large quantities of grinding chips are generated. These grinding chips result from the finishing of the blade surfaces after the primary casting process of the propeller. The aim of this study was to investigate and compare different preparation processes used to produce chip powders with sufficient powder quality for the additive manufacturing process of directed energy deposition. The preparation of the samples was performed through different sieving, milling and re-melting processes. For the characterization of the prepared samples, powder analysis according to relevant industry standards was carried out. It was found that the re-melting processes result in superior powder quality for additive manufacturing in terms of particle size, morphology, and flowability. For some characteristics, the powder exhibits even better properties than those of commercial powders. Furthermore, the powder properties of the milled samples demonstrate a promising potential for use in additive manufacturing.

Revealing dynamic processes in laser powder bed fusion with in situ X-ray diffraction at PETRA III.

The high flux combined with the high energy of the monochromatic synchrotron radiation available at modern synchrotron facilities offers vast possibilities for fundamental research on metal processing technologies. Especially in the case of laser powder bed fusion (LPBF), an additive manufacturing technology for the manufacturing of complex-shaped metallic parts, in situ methods are necessary to understand the highly dynamic thermal, mechanical, and metallurgical processes involved in the creation of the parts. At PETRA III, Deutsches Elektronen-Synchrotron, a customized LPBF system featuring all essential functions of an industrial LPBF system, is used for in situ x-ray diffraction research. Three use cases with different experimental setups and research questions are presented to demonstrate research opportunities. First, the influence of substrate pre-heating and a complex scan pattern on the strain and internal stress progression during the manufacturing of Inconel 625 parts is investigated. Second, a study on the nickel-base superalloy CMSX-4 reveals the formation and dissolution of γ' precipitates depending on the scan pattern in different part locations. Third, phase transitions during melting and solidification of an intermetallic γ-TiAl based alloy are examined, and the advantages of using thin platelet-shaped specimens to resolve the phase components are discussed. The presented cases give an overview of in situ x-ray diffraction experiments at PETRA III for research on the LPBF technology and provide information on specific experimental procedures.

Data for a simulation of metal cutting with cutting fluid using the Finite-Pointset-Method.

The measurement and simulation data, their preparation and the simulation setup published in this co-submission are related to the article "Simulation of metal cutting with cutting fluid using the Finite-Pointset-Method" [1]. Wet and dry turning experiments were conducted at the Institute for Machine Tools and Factory Management(IWF), Berlin, Germany. Required adaptions of the used software MESHFREE were performed at Fraunhofer ITWM, Kaiserslautern, Germany. Both institutes collaboratively developed and validated the orthogonal cutting simulation model using the Finite-Pointset-Method (FPM). In this paper all measurement and simulation data and their preparation methods are presented in detail. This includes the preparation methods of process forces, analysis of chip morphology images as well as measured contact lengths on tool rake faces. Moreover, the experimental and simulation data are provided at the Mendeley Data repository [2]. Hence the reader can use the data for own validations and analysis. Furthermore, the used simulation model files are completely published at the Mendeley Data repository. It allows the reader to retrace all settings. In addition, this enables to repeat the simulations and to simulate other process parameter combinations according to own interests.

Preclinical In Vitro Assessment of Submicron-Scale Laser Surface Texturing on Ti6Al4V.

Loosening of orthodontic and orthopedic implants is a critical and common clinical problem. To minimize the numbers of revision surgeries due to peri-implant inflammation or insufficient osseointegration, developments of new implant manufacturing strategies are indicated. Ultrafast laser surface texturing is a promising contact-free technology to modify the physicochemical properties of surfaces toward an anti-infectious functionalization. This work aims to texture Ti6Al4V surfaces with ultraviolet (UV) and green (GR) radiation for the manufacturing of laser-induced periodic surface structures (LIPSS). The assessment of these surface modifications addresses key aspects of topography, morphology and chemical composition. Human primary mesenchymal stromal cells (hMSCs) were cultured on laser-textured and polished Ti6Al4V to characterize the surfaces in terms of their in vitro biocompatibility, cytotoxicity, and metal release. The outcomes of the in vitro experiment show the successful culture of hMSCs on textured Ti6Al4V surfaces developed within this work. Cells cultured on LIPSS surfaces were not compromised in terms of their viability if compared to polished surfaces. Yet, the hMSC culture on UV-LIPSS show significantly lower lactate dehydrogenase and titanium release into the supernatant compared to polished. Thus, the presented surface modification can be a promising approach for future applications in orthodontics and orthopedics.

A laser powder bed fusion system for in situ x-ray diffraction with high-energy synchrotron radiation.

In Laser Powder Bed Fusion (LPBF), the highly localized energy input by the laser leads to high-temperature gradients. Combined with the inherent cycles of re-melting and solidification of the material, they can result in high mechanical stresses. These stresses can cause distortion and cracking within the component. In situ diffraction experiments with high-energy synchrotron radiation allow an analysis of the lattice spacing during the LPBF process and provide insight into the dynamics of stress generation and texture evolution. In this work, an LPBF system for the purpose of synchrotron x-ray diffraction experiments during the manufacturing process of multi-layer components with simple geometries is described. Moreover, results from diffraction experiments at the HEMS beamline P07 at PETRA III, DESY, Hamburg, Germany, are presented. Components with a length of ls = 20 mm and a width of ws = 2.5 mm consisting of 100 layers with a layer thickness of Δz = 50 µm were produced using the nickel-base alloy Inconel 625 as the powder material. Diffraction experiments were carried out in situ at sampling rates of f = 10 Hz with a synchrotron radiation beam size of 750 × 70 µm2. The presented experimental setup allows for the observation of arbitrary measuring positions in the sample in the transmission mode while gathering full diffraction rings. Thus, new possibilities for the observation of the dynamic evolution of strains, stresses, and textures during the LPBF process are provided.