A Fast Method for Predicting the Mechanical Properties of Precipitation-Hardenable Aluminum Alloys

Most heat treatment simulations of precipitation-hardenable aluminum alloys are incomplete or restricted to sub-steps of the process chain. In general, the studies addressing the heat treatment of aluminum components have only provided a qualitative guidance of heat treatment, which does not match the heat treatment that is necessary for specific parts with specific requirements. Thus, a quick and accurate simulation of the whole heat treatment process would hold great economic benefit for industrial applications in predicting suitable heat treatment processes that are able to meet the required mechanical properties of proposed novel aluminum components. In this paper, the development of a time and cost efficient method for generating such prediction models is presented by means of an example aluminum alloy EN AW-6082. During the process sub-steps of solution annealing, quenching and aging, the time-temperature correlations connected to the precipitation-hardening conditions were analyzed. The precision of the prediction model depends on the size of the material database, which should be able to be adjusted to the individual requirements of the simulation user. In order to obtain the greatest time and cost efficiency in generating such a model, a specific experimental design was developed. The results of the method development are presented and discussed

Analysis of Different 100Cr6 Material States Using Particle-Oriented Peening

As part of a novel method for evolutionary material development, particle-oriented peening is used in this work to characterize 100Cr6 (AISI 52100) microparticles that were heat-treated by means of a differential scanning calorimeter (DSC). The plastic deformation of the samples in particle-oriented peening is correlated with the microstructural properties considering different heat-treatment variations. While the heating rate was kept constant (10 K/min) for all heat treatments, different heating temperatures (500 °C, 800 °C, 1000 °C and 1100 °C) were realized, held for 20 min and then cooled down at a rate of 50 K/min. Thereby, microstructural states with different (mechanical) properties are generated. For validation, microsections of the particles were analyzed and additional universal microhardness measurements (UMH) were performed. It could be shown that the quickly assessable plastic deformation descriptor reacts sensitively to the changes in the hardness due to the heat treatment

Additive Fertigung und Eigenschaften der metastabilen Titanlegierung Ti-5Al-5Mo-5V-3Cr

Die additive Verarbeitung der Titanlegierung Ti-6Al-4V mittels pulverbettbasiertem Laserstrahlschmelzen (LPBF) ist gut erprobt und in der Luftfahrt bereits im Serieneinsatz. Dabei gibt es erhebliche Einschränkungen hinsichtlich Bauteilgestaltung und erzielbarer Maßhaltigkeit. Die Ursache dafür findet sich im thermischen Eigenspannungsprofil des Legierungssystems, was zu einem erheblichen Bauteilverzug infolge der additiven Fertigung führen kann. Daher müssen derartige Komponenten sehr steif ausgeführt werden oder es ist ein hoher Einsatz von zusätzlichem Stützmaterial erforderlich. Zur Lösung dieses Problems können metastabile Titanlegierungen, wie etwa Ti-5Al-5Mo-5V-3Cr, herangezogen werden. Der vorliegende Beitrag umfasst die LPBF-Verarbeitung der Legierung Ti-5553 mit robusten Prozesskenngrößen, resultierender Oberflächengüte sowie die Untersuchung geeigneter Wärmebehandlungen mit zugeordneten mechanischen EigenschaftenAdditive manufacturing of titanium Ti-6Al-4V by means of laser powder bed fusion (LPBF) is well established and already in use in civil aviation. However, there are considerable limitations regarding component design and achievable dimensional accuracy. The reason for this can be found in thermal residual stresses of the alloy, which can lead to significant component distortion due to additive manufacturing. Therefore, such components have to be designed very rigid or a high use of additional support material is required. To address this problem, metastable titanium alloys, such as Ti-5Al-5Mo-5V-3Cr, can be used. The present contribution covers LPBF processing of Ti-5553 with robust process parameters, resulting surface quality as well as investigations regarding suitable heat treatments with associated mechanical propertie

PBF-LB/M Ti6Al4V micrographs and labeled manufacturing defects

Desciption: This dataset contains 775 micrographs of laser additive manufactured Ti6Al4V. Further the dataset contains 1200 labeled binary images of defects classified in lack of fusion (400), keyhole (400) and process pores (400). Additional local extracted features are added as csv File. To all of the 757 micrographs are the process parameter combinations included, also for those which couldn´t be built. The process parameters were created randomly and equally distributed in between limits. The layer thicknesses included are 25 µm, 50 µm, 75 µm and 100 µm. Further the laser power, the hatch distance and the scan speed were changed. The build platform temperature was set to 200 °C. All specimens were printed an a SLM 125 HL by SLM Solutions with CL 41 Ti ELI powder by Concept Laser. Author Contributions: Conceptualisation S.M., M.L.A., L.M., A.T.; methodology for (randomised) test series: M.L.A., L.M., S.M.; data creation, printing and imaging: L.M., S.M., T.B.; defect data labeling: M.L.A., T.B.; defect feature extraction: M.L.A.; supervision: A.T.; funding acqusition : A.T. Funding: This work is funded by the University of Bremen Research Alliance (UBRA) AI Center for Healthcare within the project ENABLE

Measurement and Evaluation of Calorimetric Descriptors for the Suitability for Evolutionary High-Throughput Material Development

A novel method for evolutionary material development by using high-throughput processing is established. For the purpose of this high-throughput approach, spherical micro samples are used, which have to be characterized, up-scaled to macro level and valued. For the evaluation of the microstructural state of the micro samples and the associated micro-properties, fast characterization methods based on physical testing methods such as calorimetry and universal microhardness measurements are developed. Those measurements result in so-called descriptors. The increase in throughput during calorimetric characterization using differential scanning calorimetry is achieved by accelerating the heating rate. Consequently, descriptors are basically measured in a non-equilibrium state. The maximum heating rate is limited by the possibility to infer the microstructural state from the calorimetric results. The substantial quality of the measured descriptors for micro samples has to be quantified and analyzed depending on the heating rate. In this work, the first results of the measurements of calorimetric descriptors with increased heating rates for 100Cr6 will be presented and discussed. The results of low and high heating rates will be compared and analyzed using additional microhardness measurements. Furthermore, the validation of the method regarding the suitability for the evolutionary material development includes up-scaling to macro level and therefore different sample masses will be investigated using micro and macro samples during calorimetry

Programmable Density of Laser Additive Manufactured Parts by Considering an Inverse Problem

In this Article, the targeted adjustment of the relative density of laser additive manufactured components made of AlSi10Mg is considered. The interest in demand-oriented process parameters is steadily increasing. Thus, shorter process times and lower unit costs can be achieved with decreasing component densities. Especially when hot isostatic pressing is considered as a post-processing step. In order to be able to generate process parameters automatically, a model hypothesis is learned via artificial neural networks (ANN) for a density range from 70% to almost 100%, based on a synthetic dataset with equally distributed process parameters and a statistical test series with 256 full factorial combined instances. This allows the achievable relative density to be predicted from given process parameters. Based on the best model, a database approach and supervised training of concatenated ANNs are developed to solve the inverse parameter prediction problem for a target density. In this way, it is possible to generate a parameter prediction model for the high-dimensional result space through constraints that are shown with synthetic test data sets. The presented concatenated ANN model is able to reproduce the origin distribution. The relative density of synthetic data can be predicted with an R2-value of 0.98. The mean build rate can be increased by 12% with the formulation of a hint during the backward model training. The application of the experimental data shows increased fuzziness related to the big data gaps and a small number of instances. For practical use, this algorithm could be trained on increased data sets and can be expanded by properties such as surface quality, residual stress, or mechanical strength. With knowledge of the necessary (mechanical) properties of the components, the model can be used to generate appropriate process parameters. This way, the processing time and the amount of scrap parts can be reduced

Eccentric rotary swaging variants

Rotary swaging is an incremental cold forming process that changes beneath the geometry also the microstructure and mechanical properties of workpiece. Especially a new process design with Eccentric Flat Shaped Dies (EFSD) influences both the kind and amount of stress and plastic strain and consequently the material structure and hence the material and workpiece properties. Eccentric rotary swaging typically provides a helical material flow. According to the process parameters the microstructure features a typical eddy pattern with a spiral shaped grain orientation. The forming process can be carried out in one or more process steps. In a multi-stage process, it is possible to change the feed direction and, hence, the material flow helix direction. This approach can be used as a possibility to improve the homogeneity of the workpiece and material properties. In addition, for this aims an intermediate heat treatment in multi-stage forming operations could be realised. Following the goal of optimising the final properties, the question arises how these mechanical and thermal treatments affect the material microstructure and the forming properties of the workpiece and how they interact. Experiments were conducted with austenitic stainless steel rods of grade AISI304. The effects of the varied feed direction, feed velocity and heat treatment between the forming operations are discussed

Eccentric rotary swaging variants

Rotary swaging is an incremental cold forming process that changes beneath the geometry also the microstructure and mechanical properties of workpiece. Especially a new process design with Eccentric Flat Shaped Dies (EFSD) influences both the kind and amount of stress and plastic strain and consequently the material structure and hence the material and workpiece properties. Eccentric rotary swaging typically provides a helical material flow. According to the process parameters the microstructure features a typical eddy pattern with a spiral shaped grain orientation. The forming process can be carried out in one or more process steps. In a multi-stage process, it is possible to change the feed direction and, hence, the material flow helix direction. This approach can be used as a possibility to improve the homogeneity of the workpiece and material properties. In addition, for this aims an intermediate heat treatment in multi-stage forming operations could be realised. Following the goal of optimising the final properties, the question arises how these mechanical and thermal treatments affect the material microstructure and the forming properties of the workpiece and how they interact. Experiments were conducted with austenitic stainless steel rods of grade AISI304. The effects of the varied feed direction, feed velocity and heat treatment between the forming operations are discussed

Eccentric rotary swaging variants

Rotary swaging is an incremental cold forming process that changes beneath the geometry also the microstructure and mechanical properties of the workpiece. Especially a new process design with Eccentric Flat Shaped Dies (EFSD) influences both the kind and amount of stress and plastic strain and consequently the material structure, and hence the material and workpiece properties. Eccentric rotary swaging typically provides a helical material flow. According to the process parameters the microstructure features a typical eddy pattern with a spiral shaped grain orientation. The forming process can be carried out in one or more process steps. In a multistage process, it is possible to change the feed direction and, hence, the material flow helix direction. This approach can be used as a possibility to improve the homogeneity of the workpiece and material properties. In addition, for this aims an intermediate heat treatment in multistage forming operations could be realized. Following the goal of optimizing the final properties, the question arises how these mechanical and thermal treatments affect the material microstructure and the forming properties of the workpiece and how they interact. Experiments were conducted with austenitic stainless steel rods of grade AISI304. The effects of the varied feed direction, feed velocity and heat treatment between the forming operations are discussed

Process chain for the fabrication of hardenable aluminium-zirconium micro-components by deep drawing

Today, micro components are used in various industrial sectors such as electronics engineering and medical applications. The final quality of such parts depends on each individual step of the production chain from the manufacturing of semi-finished parts to the post-processing. In this study, magnetron sputtering is used to manufacture thin (15-30 μm) aluminium-zirconium alloy foils for the deep drawing of high strength and hardenable micro cups, which can be, for example, employed as micro valve caps. The development of a novel process chain for the production of these parts includes four different steps, beginning with the production of Al-Zr foils by magnetron sputtering. Secondly, tensile tests are performed with the foils in order to estimate their mechanical properties. Subsequently, micro deep drawing is used to produce the cup’s shape, and finally, a heat treatment in a drop-down tube furnace adjusts the cup’s hardness during fall. It is shown in particular that Al-Zr foils produced by magnetron sputtering have an attractive cold forming and hardening potential due to a microstructure consisting essentially of an oversaturated solid solution of zirconium in the aluminium matrix. This material state enables adequate formability and simplifies the heat treatment process since no solution annealing is required