scholarly journals Influence of Local Porosity on the Mechanical Properties of Direct Metal Laser-Sintered 1.2709 Alloy

2020 ◽  
Vol 66 (6) ◽  
pp. 351-357
Author(s):  
István Hatos ◽  
Imre Fekete ◽  
Dóra Harangozó ◽  
Hajnalka Hargitai
Keyword(s):  
Mechanical Properties ◽  
Tool Steel ◽  
Steel Powder ◽  
Great Flexibility ◽  
Powder Bed ◽  
Metal Printing ◽  
Local Porosity ◽  
Technological Limitations ◽  
Complex Parts

Powder bed metal printing has demonstrated its potential for the direct manufacturing of complex parts. It has great flexibility compared to conventional manufacturing. There are also some difficulties and problems, e.g., because the process stops during production. When the process is restarted, the first layer may be thicker due to technological limitations. In this paper, the effects caused by the presence of these thicker layers were investigated. The possibility of re-melting the layers to reduce porosity were also analysed. A tool steel powder grade 1.2709 was used to produce samples with an increased thickness of melted layers.

scholarly journals Improved Process Efficiency in Laser-Based Powder Bed Fusion of Nanoparticle Coated Maraging Tool Steel Powder

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3465
Author(s):  
Oliver Pannitz ◽  
Felix Großwendt ◽  
Arne Lüddecke ◽  
Arno Kwade ◽  
Arne Röttger ◽  
...  
Keyword(s):  
Tool Steel ◽  
Steel Powder ◽  
Process Efficiency ◽  
Powder Materials ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Laser Systems ◽  
Additional Improvement ◽  
Few Layer Graphene ◽  
The Impact

Research and development in the field of metal-based additive manufacturing are advancing steadily every year. In order to increase the efficiency of powder bed fusion of metals using a laser beam system (PBF LB/M), machine manufacturers have implemented extensive optimizations with regard to the laser systems and build volumes. However, the optimization of metallic powder materials using nanoparticle additives enables an additional improvement of the laser–material interaction. In this work, tool steel 1.2709 powder was coated with silicon carbide (SiC), few-layer graphene (FLG), and iron oxide black (IOB) on a nanometer scale. Subsequently, the feedstock material and the modified powder materials were analyzed concerning the reflectance of the laser radiation and processed by PBF-LB/M in a systematic and consistent procedure to evaluate the impact of the nano-additivation on the process efficiency and mechanical properties. As a result, an increased build rate is achieved, exhibiting a relative density of 99.9% for FLG/1.2709 due to a decreased reflectance of this modified powder material. Furthermore, FLG/1.2709 provides hardness values after precipitation hardening with only aging comparable to the original 1.2709 material and is higher than the SiC- and IOB-coated material. Additionally, the IOB coating tends to promote oxide-formation and lack-of-fusion defects.

scholarly journals Powder bed selective laser process (sintering/melting) applied to tailored calcium phosphate-based powders

2021 ◽  
Author(s):  
Pedro Navarrete-Segado ◽  
Christine Frances ◽  
Mallorie Tourbin ◽  
Christophe Tenailleau ◽  
Benjamin Duployer ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Process Window ◽  
X Ray Diffraction ◽  
Powder Bed ◽  
Laser Process ◽  
Whole Process ◽  
Vibrational Spectroscopies ◽  
Complex Parts

This paper focuses on the tailoring of calcium phosphate powders for their use as powder bed selective laser process feedstock. Hydroxyapatite and chlorapatite were used as starting powders for the preparation of different blends through the addition of graphite as a laser absorptance additive. A methodical study was conducted to compare the processing windows of the blends containing different amounts of graphite through the laser patterning of circular samples. It was found that the addition of graphite increases the process window of the powder blends being the powder without additive non processable. Hydroxyapatite showed a clear phase transition (decreased when using higher volumetric energy density) into other calcium phosphate phases while chlorapatite was demonstrated to be thermally stable during the whole process (examined through X-ray diffraction and vibrational spectroscopies). In parallel, the study evaluating the powder blend composed of hydroxyapatite and graphite for the production of solid and complex parts was carried out although it required long printing times. The productivity of the process was improved by modification of printing parameters. Then, a series of solid samples were produced for the analysis of the microstructure and mechanical properties. High interconnected porosity was observed in the samples which could improve the bioactivity of the bioceramic scaffolds. A post-treatment of the parts increased their proportion in the hydroxyapatite phase and their mechanical properties. These results are expected to contribute to the application of powder bed selective laser processing of calcium phosphates powders toward bone tissue engineering.

scholarly journals On the advances to obtain excellent and repeatable mechanical properties and build quality of LaserForm® Ti gr23 (A) across whole build platform

2020 ◽  
Vol 321 ◽  
pp. 03015
Author(s):  
Anthony Beckers ◽  
Gokula Krishna Muralidharan ◽  
Karel Lietaert ◽  
Nachiketa Ray ◽  
Pierre Van Cauwenbergh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Gas Flow ◽  
Hot Isostatic Pressing ◽  
Fatigue Properties ◽  
Powder Bed ◽  
Part Quality ◽  
Metal Printing ◽  
Wide Range ◽  
Better Than

Direct Metal Printing (DMP) or Laser Based Powder Bed Fusion (L-BPF) enables manufacturing of highly complex geometries which are used in a wide range of applications - healthcare to aerospace. Producing these products with excellent and consistent part quality in terms of density and mechanical properties is key. DMP ProX® 320 machine has been used for over 10 years for this purpose. In this study, the key improvements made on the process stability for targeting consistent build quality across build platform and repeatability have been evaluated. The quality is assessed by determining the density, mechanical properties and surface roughness of direct metal printed LaserForm® Ti gr23 (A). The main finding from the study is that the use of the optimized gas flow enables production of LaserForm® Ti gr23 (A) with consistent and improved mechanical properties across the whole build platform. Moreover, there is no need any more for hot isostatic pressing to ensure good fatigue properties. The elongation strain to failure increased by 15 % to 20 %, which is 4-5 % higher than ASTM F3001 specifications. The axial fatigue limit (5x106 loading cycles) was 637 MPa (R=0.1), which is as good as or even better than annealed wrought Ti6Al4V.

scholarly journals Processing of AISI H11 Tool Steel Powder Modified with Carbon Black Nanoparticles for the Additive Manufacturing of Forging Tools with Tailored Mechanical Properties by Means of Laser Metal Deposition (LMD)

Metals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 659 ◽  
Author(s):  
Oliver Hentschel ◽  
Laurids Siegel ◽  
Christian Scheitler ◽  
Florian Huber ◽  
Daniel Junker ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Carbon Black ◽  
Tool Steel ◽  
Vickers Hardness ◽  
Steel Powder ◽  
Metal Deposition ◽  
Laser Metal Deposition ◽  
Powder Mixtures ◽  
Carbon Black Nanoparticles

Within the scope of the presented work the processing of AISI H11 (1.2343 or X37CrMoV5-1) tool steel powder modified by adding carbon black nanoparticles in varying concentrations by means of Laser Metal Deposition (LMD) is extensively investigated. On the basis of single weld track experiments, multi-layered cuboid-shaped samples made out of pure AISI H11 tool steel powder as well as modified tool steel powder mixtures were manufactured by applying various process parameters. The main scientific aim of the investigations was to achieve a basic understanding of the influence of the added carbon black nanoparticles on the resulting sample properties. For that purpose, the generated specimens were first analyzed with respect to relative density, inner defects, microstructure, Vickers hardness and chemical composition. Subsequently, the mechanical properties of post-heat-treated specimens were investigated, with the focus on the yield strength (Y0.2%), by means of compression tests. We prove that by adding carbon black nanoparticles to the initial AISI H11 powder, the formation of martensitic and bainitic phases, as well as the precipitation of carbides at the grain boundaries, are enhanced. As a result, a significant increase of Vickers hardness and of the compression yield strength by up to 11% can be achieved in comparison to samples made out of the unmodified AISI H11 powder. Furthermore, it can be fundamentally demonstrated that the fabrication of parts with layer-specific variable hardness can be realized by the controlled changing of the powder mixtures used during the layer-by-layer manufacturing approach.

scholarly journals Hybrid additive manufacturing of hot working tool steel H13 with dissimilar base bodies using Laser-based Powder Bed Fusion

2021 ◽  
Vol 1135 (1) ◽  
pp. 012012
Author(s):  
Lukas Langer ◽  
Matthias Schmitt ◽  
Jaime Cuesta Aguirre ◽  
Georg Schlick ◽  
Johannes Schilp
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Tool Steel ◽  
Hot Working ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Post Process ◽  
Aisi H13 ◽  
Bonding Zone ◽  
Free Material

Abstract Hybrid additive manufacturing (HAM) describes the combination of additively built structures onto a conventionally manufactured base body. The advantages of both manufacturing processes are combined in one process chain. As a result, new applications can be achieved with higher cost-effectiveness. With the Additive Manufacturing (AM) process a bonding zone is created that is comparable to a welded joint. In order to evaluate the quality and mechanical properties of the bonding zone, two steels (42CrMo4 and 25CrMo4) are investigated as base body materials with the hot working tool steel X40CrMoV5-1 (AISI H13) for the AM structure. Process parameters for Laser-based Powder Bed Fusion of X40CrMo4V5-1 are developed to achieve a crack and defect free structure as well as an optimized bonding zone in dependency of the base body material. Furthermore, the chemical and mechanical properties are examined in the as-built and heat-treated state. It is observed that a crack-free material bonding is possible and samples with relative densities above 99.5% are obtained. The size of the bonding zone depends on the material of the base body as well as post-process heat treatment. An average hardness of 600 HV1 can be achieved in the “as-built” state.

Raster scan selective laser melting of the surface layer of a tool steel powder bed

2005 ◽  
Vol 219 (4) ◽  
pp. 379-384 ◽  
Author(s):  
T H C Childs ◽  
C Hauser
Keyword(s):  
Selective Laser Melting ◽  
Tool Steel ◽  
Laser Energy ◽  
Steel Powder ◽  
Beam Diameter ◽  
Laser Melting ◽  
Powder Bed ◽  
H13 Tool Steel ◽  
Scan Speed ◽  
The Masses

Square areas, 15 mm × 15 mm in size, have been melted in the surface of powder beds made from H13 tool steel, using a raster-scanning CO2 laser focused to a beam diameter of 0.6 mm. Laser powers from approximately 50 to 150 W and scan speeds from 0.5 to 300 mm/s have been used, at two scan spacings, 0.15 mm and 0.45 mm. The appearances of the layers in the different conditions, dense or porous, have been observed by low-magnification scanning electron microscopy. The masses of the layers have been measured and simulations have been carried out to predict the masses. The variation of mass with scan speed, at a constant laser power, has been found to be much less than might be expected from a constant absorptivity of laser energy into the bed. The simulations suggest that absorptivities range from 0.25 to approximately 1.0 and that, during any one scan, heating of the bed by previous scans must be considered in order even partially to explain the observations. The work is relevant to attempts to build metal parts without supports, by selective laser melting.

scholarly journals Laser Welding of AISI 316L Stainless Steel Produced by Additive Manufacturing or by Conventional Processes

2021 ◽  
Vol 5 (4) ◽  
pp. 136
Author(s):  
Morgane Mokhtari ◽  
Pierrick Pommier ◽  
Yannick Balcaen ◽  
Joel Alexis
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Laser Welding ◽  
Aisi 316L Stainless Steel ◽  
Powder Bed ◽  
Size Limitation ◽  
Common Technique ◽  
Cold Rolled ◽  
Manufacturing Techniques ◽  
Complex Parts

Among all the additive manufacturing techniques, Laser Powder Bed Fusion (LBPF), also called Selective Laser Melting (SLM), is the most common technique due to its high capability of building complex parts with generally improved mechanical properties. One of the main drawbacks of this technique is the sample size limitation, which depends on elaborating chamber dimensions. In this study, we investigate the viability of obtaining large parts with the laser welding of additive manufactured plates. A comparison of the microstructure and the tensile mechanical properties of SLM-welded plates and cold-rolled welded plates was performed. This paper shows the possibility of obtaining defect-free parts. Even if welding has a low impact on the microstructure of the SLM samples, fractures are located on the fusion zone, and a decrease in ductility of around 30% compared to the base metal is observed.

scholarly journals Influence of Different Alloying Strategies on the Mechanical Behavior of Tool Steel Produced by Laser-Powder Bed Fusion

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3344
Author(s):  
Abootorab Baqerzadeh Chehreh ◽  
Anna Strauch ◽  
Felix Großwendt ◽  
Arne Röttger ◽  
Rainer Fechte-Heinen ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Tool Steel ◽  
Defect Density ◽  
Steel Powder ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Static Mechanical ◽  
Particle Parameters

Additive manufacturing is a high-potential technique that allows the production of components with almost no limitation in complexity. However, one of the main factors that still limits the laser-based additive manufacturing is a lack of processable alloys such as carbon martensitic hardenable tool steels, which are rarely investigated due to their susceptibility to cold cracking. Therefore, this study aimed to expand the variety of steels for laser powder bed fusion (L-PBF) by investigating an alternative alloying strategy for hot work tool steel powder. In this study, a comprehensive investigation was performed on the powder and L-PBF processed specimen properties and their correlation with the existing defects. Cubical specimens were created using the following two alloying strategies by means of L-PBF: conventional pre-alloyed gas-atomized powder and a mixture of gas-atomized powder with mechanically crushed pure elements and ferroalloys. The influence of the particle parameters such as morphology were correlated to the defect density and resulting quasi-static mechanical properties. Micromechanical behavior and damage evolution of the processed specimens were investigated using in situ computed tomography. It was shown that the properties of the L-PBF processed specimens obtained from the powder mixture performs equal or better compared to the specimens produced from conventional powder.

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