Suchergebnisse

Additive Manufacturing (AM) ist der Überbegriff für unterschiedliche Fertigungsverfahren, welche durch das schichtweise Aufbringen von Werkstoff die Herstellung von Bauteilen ermöglichen. Selective Laser Melting (SLM) ist ein additives Fertigungsverfahren zur Herstellung von Produkten mit hoher Detailgenauigkeit und Designfreiheit. Der Fachbeitrag stellt ein Konzept vor, bei dem durch systematisches Vorgehen untersucht wird, ob Produktanforderungen mit SLM besser erfüllt werden können als mit konventionellen Fertigungsverfahren.
 
Additive Manufacturing (AM) is the term for various manufacturing technologies that enable manufacturing of components by adding layer after layer of material. Selective Laser Melting (SLM) is an additive manufacturing technology that allows to manufacture products with high accuracy and design freedom. In this article an approach is presented to systematically examine, if product requirements can be fulfilled better with SLM than with conventional manufacturing technologies.

The present study is focused on rheological properties of AlSi10Mg aluminium alloy produced by selective laser melting (SLM) at temperatures of hot deformation with the aim to investigate the dependence of strain resistance on temperature, strain rate and strain degree. As-build cylindrical specimens made of AlSi10Mg aluminium alloy was examined on a cam plastometer in temperature range 20 - 500 °C, at strain rate ξ equal to 1, 10 s-1 up to strain degree e equal to 1.2. The paper presents results of study of initial microstructure, microhardness measurement and flow curves of AlSi10Mg alloy produced by SLM. The flow curves of AlSi10Mg alloy produced by SLM can be used in the computer simulation and development of new manufacturing methods of the metallic parts by additive technologies with the use of deformation post-treatment. © Published under licence by IOP Publishing Ltd. ; Government Council on Grants, Russian Federation ; The study was made within the basic part of the state job in the field of scientific activity No. 11.9538.2017/8.9 and was supported by Act 211 of the Government of the Russian Federation (agreement No. 02.A03.21.0006).

The article presents the results of characterization of special powders of metal alloys and materials produced from these powders by selective laser melting (SLM), including comparative analysis of powders produced using VIGA technology. It is noted the importance of a complex study that includes not only a statistical evaluation of particle size distribution of the powders (preferably, by the method of laser diffraction), but also image analysis providing information on the particles' shape influencing the powders' flowability. It is shown that the size distribution and shape metrics for nickel refractory alloys and stainless steel powders obtained at the Powder Metallurgy Institute of the National Academy of Sciences of Belarus are at the level of the best foreign analogues. The influence of powder chemical composition on the mechanical properties of SLM samples is considered. The presence of oxygen and undesirable impurities, as a rule, decreases the strength and tensile strain. It is noted that SLM provides extremely wide opportunities for the formation of complex geometric structures with close to full density. Subsequent thermal or thermal and mechanical processing allows reduction of stresses arising during the SLM, densification of products (if necessary) and regulation of their structure and properties. The prospects of applying the backscattered electron diffraction (EBSD) for analysis of the material structure evolution during SLM and subsequent processing are shown. It is noted that products obtained by the SLM from the powders of special alloys exhibit mechanical properties at a level, and in some cases even exceeding the properties of these alloys produced by traditional and other additive technologies.

This study focuses on the dwell-fatigue crack propagation behavior of IN718 manufactured via selective laser melting (SLM). The dwell-fatigue test condition is 823 K (550 with a long 2160-s dwell-holding period. Effects of heat treatment and loading direction on dwell-fatigue crack propagation rates are studied. A grain boundary delta precipitate seems to be slightly beneficial to the dwell-fatigue cracking resistance of SLM IN718. A comparison has been made between SLM IN718 and forged counterparts at different temperatures, indicating that a creep damage mechanism is likely dominant for SLM IN718 under the present test condition. A general discussion of the inferior creep resistance of SLM IN718 is also included. The anisotropic dwell-fatigue cracking resistance has also been studied and rationalized with the effective stress intensity factor calculated from finite element modeling. ; Funding Agencies|Linkoping University; Siemens AG in Berlin, Germany; Faculty grant SFO-MAT-LiU at Linkoping University [2009-00971]; Chinese Scholarship CouncilChina Scholarship Council; Agora Materiae; Swedish Governmental Agency for Innovation Systems (Vinnova grant) [2016-05175]

Strain rate dependent deformation behaviours of selective laser melted Alloy 718 (IN718) are systematically studied at 550 and 650 °C by slow strain rate testing, with a forged counterpart as a reference. Selective laser melted IN718 shows significant susceptibility to intergranular cavitation, resulting in ductility degradation with decreasing strain rate. Detailed fractography and cross section inspections are employed to identify the damage mechanisms. Creep rates are also estimated and compared with the conventional counterparts. The possible critical factors for the inferiority of time dependent damage resistance of selective laser melted IN718 are discussed. ; Funding: Faculty grant SFOMATLiU from Linkoping University [200900971]; Swedish Governmental Agency for Innovation Systems (Vinnova)Vinnova [2016-05175]