Developing Tungsten-Filled Metal Matrix Composite Materials Using Laser Powder Bed Fusion

The additive manufacturing technique laser powder bed fusion (L-PBF) opens up potential to process metal matrix composites (MMCs) with new material pairings free from limitations of conventional production techniques. In this work, we present a study on MMC material development using L-PBF. The generated composite material is composed of an X3NiCoMoTi 18-9-5 steel as matrix and spherical tungsten particles as filler material. A Design of Experiment (DoE)-based process parameter adaption leads to an Archimedean density close to the theoretical density in the case of 60 vol% tungsten content. A maximum ultimate tensile strength of 836 MPa is obtained. A failure analysis reveals a stable bonding of the tungsten particles to the steel matrix. This encourages the investigation of further material combinations. An additional heat treatment of the MMC indicates the potential to design specific material properties; it also highlights the complexity of such treatments

Designed Materials by Additive Manufacturing—Impact of Exposure Strategies and Parameters on Material Characteristics of AlSi10Mg Processed by Laser Beam Melting

The Laser Beam Melting (LBM) Additive Manufacturing technology for metal processing is based on the local application of an intense laser beam, causing a characteristic microstructure, which can achieve higher mechanical properties than conventionally manufactured equivalents. The material is created incrementally in sections that are processed with different manufacturing parameters. This paper proposes the creation of Designed Materials by varying the manufacturing parameters and exposure strategy in order to induce a gradient or a local change of properties by designing the microstructure. Such materials could also be created by changing the material topology on a micro-, meso-, or macro-scale, or on multiple scales at once. This enables systematic creation of material types like Functionally Graded Materials (FGMs), Metamaterials, or other Designed Materials, in which characteristics can be varied locally in order to create a customized material. To produce such materials by LBM, it is necessary to gain a detailed understanding about the influence of the manufacturing parameters. Experimental studies have been carried out to investigate the melt pool geometry and microstructure resulting from the exposure parameters. Based on the results, parameter sheets have been derived, which support the process of finding optimized parameter sets for a specific purpose. General methods and their ability to influence the material structure and properties were tested and evaluated. Furthermore, the resulting change of the microstructure was analyzed and a first Graded Material was generated and analyzed to show the potential and possibilities for Designed Materials on multiple scales by Laser Beam Melting

Micro- and macrostructural investigations of AlSiMg produced by laser beam melting

In Laser Beam Melting (LBM), alloys like AlSi10Mg are locally melted by an intense laser beam. Specifically Designed Materials can be realized by locally varying the exposure parameters and applying diverse exposure strategies. By this approach, different micro- and macrostructures can be obtained that lead to individual mechanical properties within one part. A well-established understanding of the correlation between manufacturing parameters, generated micro- and macrostructure and resulting material properties enables the creation of complex microstructural material compositions meaning specifically Designed Materials. The interdependency of manufacturing parameters on the micro- and macrostructure was studied for different exposure strategies in LBM processing of AlSi10Mg using a 1 kW laser source and building layers of 90 μm. The investigations focus on the analysis of data obtained by imaging techniques like light and scanning electron microscopy. In particular, melt pool boundaries and crystal grains are examined

A parametric mesostructural approach for robust design of additive manufacturing parts

Additive Manufacturing (AM) allows for production of potentially complex design solutions and motivates the use of Structural Optimization tools in product development to chase the structural limit of a design problem and its solution concept. Scratching on the limits of the material strength, design solutions can lack robustness concerning simplifications in model assumptions and uncertainties. However, the design freedom with AM can also actively be used to enhance robustness and reliability of solutions. To this end, an approach is presented that introduces Parametric Mesostructures into selective areas of the Additive Design. Structural members and coherent mechanical characteristics of these mesostructures can significantly reduce local stress peaks and can account for uncertainties, e.g. direction of load application. Their design is motivated by Structural Optimization and analysis results. Implementation of the approach is demonstrated and discussed on the example of a structural aircraft component

Dynamic compression of 3D printed metallic microstructures with in-situ X-ray imaging

Additive manufacturing (AM) is an attractive approach for the design and production of complex structures not possible to realize with conventional methods. While the dynamic mechanical response of bulk material is object of extensive investigation, the dynamic behavior of mesostructured material is lacking attention. In this study, a series of different mesostructures, such as lattice and auxetic structures, was designed and additively manufactured in Ti-6Al-4V by laser beam melting (LBM). Dynamic compression tests at velocities around 150 – 360 m/s were conducted at selected samples using a gas-gun. InsituX-ray imaging provided image data showing an influence of the design of the mesostructure on its failure behavior. Numerical simulations of the impact were compared to the experiments demonstrating a promising accordance. The results enable improved numerical simulation models enhancing their prognostic capacity. Moreover, the findings support the development of design approaches considering the structure-dependent failure behavior