World PM2022 Proceedings

Authors:

Federico Simone Gobber (Politecnico di Torino, Italy), Marco Actis Grande (Politecnico di Torino, Italy)

Abstract:

Duplex stainless steels represent a very promising alternative when aggressive|marine atmospheres characterize the component’s final application. In this frame, grades with higher Pitting Resistance Equivalent Number (40 or above) may be used in hydrogen sulphide and chloride-containing environments. UNS 32760 Duplex Stainless Steel powders have been obtained by means of close coupled gas atomization, starting from wrought bars. The paper analyses the effect of different parameters on the characteristics of the final powder, in terms of granulometry, orphology, microstructure, and chemical composition (compared to the starting material), also taking into account light elements as N, O, H, C, and S.

DOI:

https://doi.org/10.59499/WP225372042

Authors:

Markus Schneider (GKN Sinter Metals Engineering GmbH, Germany), Herbert Danninger (Technische Universität Wien, Austria)

Abstract:

Induction hardening and induction tempering gain increasing importance for heat treating of sintered steels due to high reproducibility and the chance for subsequent soft machining of not heat-treated part regions. Due to the high heating rates and the short processing times during the inductive heating the diffusion processes have to be accelerated by higher temperature. This results in higher austenitizing and tempering temperatures compared to classical furnace heat treatments. In the presence of absorbed nitrogen higher tempering temperatures might result in blue brittleness (300 °C embrittlement), an aging effect caused by the precipitation of nitrides. Based on that working hypothesis four different sintered steels were hardened and tempered under varying conditions. The hardness and the impact toughness were analyzed to check whether a drop of the toughness can be observed at a certain tempering temperature level. Moreover, the absorbed nitrogen contents were measured.

DOI:

https://doi.org/10.59499/WP225369527

Authors:

Yang Tian (Monash University, Australia), Derui Jiang (Monash University, Australia), Xinhua Wu (Monash University, Australia)

Abstract:

Metal powder characteristics can affect the build quality of laser powder bed fusion produced (LPBF) parts. In this study, two batches of Hastelloy X powder with different powder characteristics including powder chemical compositions, morphologies, amounts of inclusions, and size distributions were compared in terms of the subsequent flowability, printing quality, and microstructures. Metal powder with irregular surface morphologies and large number of inclusions was found to be undesirable to the building quality. This was mainly attributed to the poor powder spreading quality on the build plate. Whereas metal powder with uniform circular morphology and less inclusions showed the best printing quality. Cracking issue was found in the LPBF produced HX microstructure, which was sensitive to the amount of Si, Mn and C contents.

DOI:

https://doi.org/10.59499/WP225366563

Authors:

Aitor Amatriain (CEIT, Spain), Ernesto Urionabarrenetxea (CEIT, Spain), Martin José M. (CEIT, Spain)

Abstract:

Computer simulation of metal powder gas atomisation aims to better understand the complex phenomena involved in the interaction between gas and liquid metal, in order to maximize productivity and to avoid common issues. An efficient axisymmetric simulation of primary and secondary atomisation is proposed, which reduces calculation time in conventional desktop computer to the range of few hours. Primary atomisation is modeled using a Eulerian model that predicts the gas|liquid ratio in the neighborhood of the melt delivery tube. The secondary atomisation uses a Lagrangian particle tracking approach with a multimodal breakup model to predict particle breakup, and thus particle size distribution. Transition from the primary to the secondary atomisation takes place at the iso-surface of void fraction equal to 90%, which is adopted as injection surface. Particle size distributions of gas-atomised copper powder obtained with simulations are compared with experimental results.

DOI:

https://doi.org/10.59499/WP225371452

Authors:

Fredrik Olsson (Höganäs AB, Sweden), Maheswaran Vattur Sundaram (Höganäs AB, Sweden)

Abstract:

The enhanced strength and performance of the PM steels are attributed to its martensitic microstructure from heat treatment process. However, in the as-quenched state, the metastable martensite is brittle, and to improve the toughness and the phase stability, tempering is performed. In PM steels, the performance can be further enhanced by the addition of Ni and heat treatment after sintering in form of casehardening by low-pressure carburizing (LPC). The combined effect on the obtained microstructure needs to be understood and optimized to maximize the overall performance. This paper investigates the effect of microstructural changes due to tempering a chromium pre-alloyed PM steel with and without Ni additions after LPC utilizing Electron Backscatter Diffraction (EBSD).

DOI:

https://doi.org/10.59499/WP225371528

Authors:

Alex Wehrli (Osterwalder AG, Switzerland)

Abstract:

Energy cost and overall equipment efficiency have triggered the development of large electric powder compacting presses.Additionally, several OEMs have announced the implementation of stronger regulations in their supply chain with the aim to reduce the grey energy.With the increased complexity and precision of PM parts, hydraulic CNC presses have replaced the mechanical presses. By implementing high|low-pressure systems, fast movement actuators and intelligent pump technology, the energy efficiency was increased, but there remains a very high energy demand compared to the actual net energy required for compacting a part.In this study the energy consumption of hydraulic and electric drive systems for the upper ram and the die of a compacting press is calculated and compared with the actual net energy demand of a compaction part.It will be shown why and by what amount the electric drive outperforms the hydraulic drive when it comes to energy efficiency.

DOI:

https://doi.org/10.59499/WP225367791

Authors:

Michael Andersson (Höganäs AB, Sweden)

Abstract:

Gears are an interesting application for pressed and sintered applications, and having accurate fatigue data is often a pre-requisite for starting a new gear design. Ideally gear fatigue strength is tested on gears, but that is not always possible. At the same time standard bending fatigue data are often more readily available. Therefore, it’s interesting to have reliable methods for going from, for instance, bending fatigue strength on a test bar to tooth root fatigue strength of a gear. This paper investigates how gear fatigue strength can be calculated from test bar data and the results are compared with pulsator testing of gears.

DOI:

https://doi.org/10.59499/WP225371871

Authors:

Philip Sperling (Volume Graphics GmbH, Germany), Nils Achilles (Yxlon International GmbH, Germany), Torben Kuhnt (Yxlon International GmbH, Germany), Lea Reineke (Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Germany), Bastian Barthel (Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Germany)

Abstract:

Metal Binder Jetting (MBJ) offers many advantages, as the material variety also includes non-weldable materials and is capable of higher build rates compared to other powder bed-based processes, which makes the process interesting from an economical perspective. In contrast to other powder bed-based processes the binder application is unique. The aim of this work is to characterize and analyse the porosity distribution of the green parts by computed tomography. The parameters binder saturation and layer thickness are varied. These results show that binder application leads to porosity in green and sintered parts due to droplet impact. A higher binder saturation can compact the particle structure in the green part due to capillary forces. This also results in a better inter-layer bonding and leads to a lower anisotropy of the shrinkage. Resulting particle segregation in the powder bed & green part are due to powder application by a counter rotating roller.

DOI:

https://doi.org/10.59499/WP225372057

Authors:

Paul Calves (Centre Technique des Industries Mécaniques (CETIM), France), Maxime Robert (Centre Technique des Industries Mécaniques (CETIM), France), Corentin Carree (Centre Technique des Industries Mécaniques (CETIM), France)

Abstract:

Today, the building rates with Metal Binder Jetting technologies start to reach very high rates, giving good perspectives for mass production. But one remaining challenge is also to master the dimensional dispersion in production, and to guarantee an Interval of Tolerance satisfying industrial specifications and needs.This presentation will detail in a first part, the progression towards a reliable and efficient method allowing to evaluate the dimensional dispersion of Metal Binder Jetting machines.Then several results and observations, among other the Interval of Tolerance depending on some printing parameters and observables as green and as sintered, will be presented and discussed.

DOI:

https://doi.org/10.59499/WP225370845

Authors:

Louise Toualbi (ONERA, France), Yann Le Bouar (ONERA, France), Jean-Sébastien Mérot (ONERA, France), Federico Orlacchio (ONERA, France), Pauline Stricot (ONERA, France), Agnès Bahcelier-Locq (ONERA, France), Nicolas Horezan (ONERA, France), Denis Boivin (ONERA, France), Cécile Davoine (ONERA, France), Marc Thomas (ONERA, France)

Abstract:

The L-PBF process features very short interactions between the powder and the laser, resulting in very high solidification and cooling rates. During thermal cycling in L-PBF processing, phase precipitation and thermal strain hardening occur concomitantly, thus leading to high dislocation density correlated with anchoring to precipitates. It is therefore important to understand and control precipitation kinetics with respect to the thermal strain hardening phenomena generated by the thermal cycles of the L-PBF process. This issue concerns structural hardening aluminium alloys.The aim of this study is to understand the thermal, metallurgical and mechanical phenomena generated during the manufacture of a model aluminium alloy (Al-4Fe) by L-PFB, in order to evaluate the impact of thermal strain hardening on the precipitation of the strengthening phases. A fine microstructural characterization using scanning electron microscopy and transmission electron microscopy shows a strong the interaction between dislocation density and precipitation.

DOI:

https://doi.org/10.59499/WP225371451

Authors:

Sohret Melda Aydin (EGE University, Turkey), Tugçe Tekin (EGE University, Turkey)

Abstract:

Commercial purity Mg powders were sintered at 300°C for 15 minutes with alternating current electric field-assisted sintering technique (FAST) under the pressure of 30 MPa after mechanical milling for 4-8-12-16-20 hours. Powder geometries, sizes and microstructural properties of the powders were investigated depending on the milling time. The relationship between the pore ratio and pore structure of the sintered samples and their powder geometries was investigated. Depending on the powder microstructure and geometry, the realization mechanism of FAST has been examined and evaluated with the results of compressive strength and hardness tests. The results were supported by optical microscope images, Scanning Electron Microscope (SEM) images. It has been determined that powder geometries (platy-spherical) -especially in the FAST method- have a great effect on sinterability and pore size, shape, and distribution.

DOI:

https://doi.org/10.59499/WP225370249

Authors:

Rafik Safar Bati (Univ. Grenoble Alpes, France), Marco Zago (Univ. Grenoble Alpes, France), Jean-Michel Missiaen (Univ. Grenoble Alpes, France), Didier Bouvard (Université Grenoble Alpes, France), Jean-Marc Chaix (Univ. Grenoble Alpes, France), Faisal Balarabe (Univ. Grenoble Alpes, France), Yvan Avenas (Univ. Grenoble Alpes, France)

Abstract:

The interest of composite extrusion modelling (CEM) for additive manufacturing of metal components is growing up due to the low cost of this process and to the possibility of using commercial MIM feedstock. In a previous study, the successive stages of the processing route of simple copper parts have been optimised with regard to the final weight density and surface roughness. The next step has consisted in fabricating components with controlled porous architecture, to be used for cooling power electronic chips with an air flow. The thermo-hydraulic properties of these components (thermal resistance, air pressure drop) have next been measured. For future practical application of this heat sink, its bonding to a copper plate has been ensured by printing the feedstock directly upon the plate and next sintering the assembly. The shear resistance of this bonding has been found to be in line with power electronics standards.

DOI:

https://doi.org/10.59499/WP225367584