Bruno Buchmayr

Based on high energy demand of the primary production and losses during secondary production, alternative recycling of aluminum becomes a popular research topic. Compared to both primary and secondary production of aluminum, solid state recycling offers energy savings and reduced material losses during processing by surpassing an inefficient melting step. In this work, a direct recycling route for machining chips via pulsed electric current sintering (PECS) is evaluated. Therefore, necessary processing steps for a complete recycling route are briefly outlined. After cleansing, EN AW 6082 chips, provided by Neuman Aluminium GmbH, Marktl, Austria, are compacted with variable loads and consolidated via PECS on two separate systems to enable a comparison. Produced specimens are examined with density measurements, optical microscopy and the bonding quality is evaluated by Vickers micro-hardness measurements. In combination with elevated temperature and deformation, applied current promotes consolidation amongst chips and improvements in density, hardness and microstructure are achieved. The results of this work clearly show a positive effect of PECS on the bonding amongst chips, but further research will be necessary to separate and understand influences of single processing parameters. Additionally, all processing steps from collection to consolidation have to be taken into account to achieve industrial implementation.

Additive manufacturing using Selective Laser Melting (SLM) offers several advantages for industrial applications and has motivated many scientist and industrial R&D colleagues to add more and more innovations. Although the principles are well known, only a small number of materials have found a significant usage, others have shown serious problems during fabrication. In the paper, the influencing process parameters, the interactions of important mechanisms and the microstructural based assessment of laser weldability as well as the appearance of defect formations are considered in detail in order to understand the physical limits and to highlight the peculiarities of the SLM-process. Many problems can be solved using the lessons learned in welding technology. On one side, the high cooling rate and strong undercooling of SLM-process is quite positive to fabricate dissimilar joints and on the other side, residual stresses and distortion may be a challenge.

Laser Powder Bed Fusion (L‐PBF) is the main technology for additive manufacturing of metallic components and is primarily used for rapid prototyping and tooling in cases with very complex geometry or lightweight design and small quantities. There are manifold influencing parameters, which need to be optimized in order to build components with suitable properties. The paper deals with three distinct application fields, like the development of new tool steel grades for injection molds, light weight design using aluminum alloys with optimized post‐weld heat treatment as well as production of copper alloys without porosity. The most sensitive process parameters are displayed and the multi‐layered components are characterized using light and high‐resolution microscopy as well as mechanical testing.