scholarly journals Processing of metal-diamond-composites using selective laser melting

2015 ◽  
Vol 21 (2) ◽  
pp. 130-136 ◽  
Author(s):  
Adriaan Bernardus Spierings ◽  
Christian Leinenbach ◽  
Christoph Kenel ◽  
Konrad Wegener
Keyword(s):  
Selective Laser Melting ◽  
Feasibility Study ◽  
Matrix Material ◽  
Outer Part ◽  
Processing Parameters ◽  
Added Value ◽  
Laser Melting ◽  
Content Type ◽  
Diamond Particles ◽  
The Matrix

Purpose – The purpose of this paper is a feasibility study that was performed to investigate the basic processability of a diamond-containing metal matrix. Powder-bed-based additive manufacturing processes such as selective laser melting (SLM) offer a huge degree of freedom, both in terms of part design and material options. In that respect, mixtures of different powders can offer new ways for the manufacture of materials with tailored properties for special applications such as metal-based cutting or grinding tools with incorporated hard phases. Design/methodology/approach – A two-step approach was used to first investigate the basic SLM-processability of a Cu-Sn-Ti-Zr alloy, which is usually used for the active brazing of ceramics and superhard materials. After the identification of a suitable processing window, the processing parameters were then applied to a mixture of this matrix material with 10-20 volume per cent artificial, Ni-coated mono-crystalline diamonds. Findings – Even though the processing parameters were not yet optimized, stable specimens out of the matrix material could be produced. Also, diamond-containing mixtures with the matrix material resulted in stable specimens, where the diamonds survived the layer-wise build process with the successive heat input, as almost no graphitization was observed. The diamond particles are fully embedded in the Cu-Sn-Ti-Zr matrix material. The outer part of the diamonds partly dissolves in the matrix during the SLM process, forming small TiC particles and most likely a thin TiC layer around the diamond particles. Originality/value – The feasibility study approved the SLM processing capabilities of a metal-diamond composite. Although some cracking phenomena sill occur, this seems to be an interesting and promising way to create new abrasive tools with added value in terms of internal and local lubrication supply, tooling temperature control and improved tooling durability.

scholarly journals Optimisation of selective laser melting parameters for the Ni-based superalloy IN-738 LC using Doehlert’s design

2017 ◽  
Vol 23 (5) ◽  
pp. 881-892 ◽  
Author(s):  
Nataliya Perevoshchikova ◽  
Jordan Rigaud ◽  
Yu Sha ◽  
Martin Heilmaier ◽  
Barrie Finnin ◽  
...  
Keyword(s):  
Image Analysis ◽  
Relative Density ◽  
Selective Laser Melting ◽  
Processing Parameters ◽  
Powder Alloy ◽  
Operating Parameters ◽  
Laser Melting ◽  
Doehlert Design ◽  
Feasible Set ◽  
Content Type

Purpose The Ni-based superalloy IN-738 LC is known to be susceptible to porosity and different types of cracking during the build-up process and, thus, challenging to manufacture using selective laser melting (SLM). Determining a feasible set of operating parameters for SLM of nickel-based superalloys involves new approach to experimental design based on the Doehlert method that assists in determining an optimal (feasible) set of operating parameters for SLM of IN-738 LC powder alloy. Design/methodology/approach The SLM parameters are evaluated in terms of their effectiveness in obtaining the microstructure with a porosity content of <0.5 per cent and without micro-cracking. The experimental approach is exemplified with the Doehlert matrix response variable, relative density, by comparing Archimedes method with microstructural assessments of pores and cracks from image analysis. The effect of heat treatment (HT) and hot isostatic pressing (HIP) on the microstructure of the SLMed IN-738 LC powder alloy has been examined and the consequential tensile response characterised. Findings By using optimised process parameters (low heat input, medium scanning speed and small hatching distance) which provides medium energy density, samples of IN-738 LC with a macroscopic porosity <0.5 per cent and free of micro-cracks can be manufactured by SLM. The results indicate that HIP of SLMed material did not lead to a noticeable effect on mechanical properties compared to HT of SLMed material suggesting that the level of both porosity and crack density might be already below the detection limit for the mere heat-treated material. Originality/value SLM processing parameters (power, scan speed, hatching distance) for IN-738 LC were successfully optimised after only 14 experiments using Doehlert design. Two independent methods, Archimedes method and image analysis, were used in this study to assess relative density of SLM-produced samples with sets of processing parameters showing coherency in prediction with predicted response by Doehlert design.

Effect of processing parameters on forming defects during selective laser melting of AlSi10Mg powder

2020 ◽  
Vol 26 (5) ◽  
pp. 871-879 ◽  
Author(s):  
Haihua Wu ◽  
Junfeng Li ◽  
Zhengying Wei ◽  
Pei Wei
Keyword(s):  
Selective Laser Melting ◽  
Laser Power ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Argon Pressure ◽  
Powder Layer ◽  
Laser Melting ◽  
Content Type ◽  
Scan Speed ◽  
Forming Defects

Purpose To fabricate a selective laser melting (SLM)-processed AlSi10Mg part with almost full density and free of any apparent pores, this study aims to investigate the effect of ambient argon pressure and laser scanning speed on the particles splash during the AlSi10Mg powder bed laser melting. Design/methodology/approach Based on the discrete element method (DEM), a 3D model of random distribution of powder particles was established, and the 3D free surface of SLM forming process was dynamically tracked by the volume of fluid, where a Gaussian laser beam acts as the energy source melting the powder bed. Through the numerical simulation and process experimental research, the effect of the applied laser power and scanning speed on the operating laser melting temperature was studied. Findings The process stability has a fundamental role in the porosity formation, which is process-dependent. The effect of the processing conditions on the process stability and the resultant forming defects were clarified. Research limitations/implications The results shows that the pores were the main defects present in the SLM-processed AlSi10Mg sample, which decreases the densification level of the sample. Practical implications The optimal processing parameters (argon pressure of 1,000 Pa, laser power of 180 W, scan speed of 1,000 mm/s, powder layer thickness of 35 µm and hatch spacing of 50 µm ) applied during laser melting can improve the quality of selective laser melting of AlSi10Mg, Social implications It can provide a technological support for 3D printing. Originality/value Based on the analysis of the pore and balling formation mechanisms, the optimal processing parameters have been obtained, which were argon pressure of 1,000 Pa, laser power of 180 W, scan speed of 1,000 mm/s, powder layer thickness of 35 µm and hatch spacing of 50 µm. Then, a near-fully dense sample free of any apparent pores on the cross-sectional microstructure was produced by SLM, wherein the relative density of the as-built samples is larger than 97.5%.

The influence of a process interruption on tensile properties of AlSi10Mg samples produced by selective laser melting

2019 ◽  
Vol 25 (8) ◽  
pp. 1442-1452 ◽  
Author(s):  
Vincent Hammond ◽  
Michael Schuch ◽  
Matthias Bleckmann
Keyword(s):  
Tensile Properties ◽  
Selective Laser Melting ◽  
Continuous Process ◽  
Processing Parameters ◽  
Laser Melting ◽  
Content Type ◽  
Random Failure ◽  
Pressure Die Casting ◽  
Suitable Technique ◽  
Cylindrical Samples

Purpose The purpose of this paper is to investigate the influence of a process interruption on the tensile properties of AlSi10Mg samples produced by selective laser melting (SLM). Design/methodology/approach Using identical processing parameters, cylindrical samples were produced in either a continuous or interrupted SLM build operation. The tensile properties and microstructure of the samples were determined as a function of process type as well as orientation. Findings All samples produced in this paper displayed superior tensile properties to those produced in high pressure die casting. In general, the samples produced in the continuous build process had higher strengths and microhardness than those produced in the interrupted process. However, while most samples displayed random failure locations, the vertical samples produced in the interrupted build process showed a strong tendency for localized failure in the vicinity of the stoppage plane. Originality/value This paper demonstrated that samples produced in an interrupted build process tend to have poorer mechanical properties than those produced in a continuous process. Together, these observations highlight the importance of a suitable technique for restarting and completing an interrupted build process to ensure the production of high quality components.

Selective laser melting (SLM) of pure gold for manufacturing dental crowns

2014 ◽  
Vol 20 (6) ◽  
pp. 471-479 ◽  
Author(s):  
Mushtaq Khan ◽  
Phill Dickens
Keyword(s):  
Mechanical Properties ◽  
Layer Thickness ◽  
Surface Quality ◽  
Selective Laser Melting ◽  
Processing Parameters ◽  
Pure Gold ◽  
Laser Melting ◽  
Content Type ◽  
Dental Crowns ◽  
Suitable Processing

Purpose – This paper aims to present the application aspect of the work to manufacturing premolar and molar dental crowns by selective laser melting (SLM) of pure gold. Over the years different metals have been processed using laser-based Additive Manufacturing processes, but very little work has been published on the SLM of gold (Au). Previously published work presented suitable processing parameters for SLM of pure gold. Design/methodology/approach – Suitable processing parameters were used to manufacture premolar and molar dental crowns using SLM system. Different layer thickness was used to analyse the effect on surface quality of crowns. Mechanical properties are checked using nanoindentation and micro Computerized Tomography scanning. Findings – Dental crowns were successfully manufacturing using new build platform and suitable processing parameters. Parts were manufacturing using minimal supports which prevented parts from damaging during removal. A bed temperature of 100°C was found suitable for reducing warpage in the layers. Layer thickness of 50μm was found to have better surface quality and structural integrity as compared to 75μm. Porosity was found to be predominantly inter-layer. Small difference in mechanical properties of dental crowns is associated with the laser processing. Originality/value – This research is the first of its kind which presents dental crown manufacturing using SLM of pure gold.

Geometrical feature analysis of Co-Cr-Mo single tracks after selective laser melting processing

2015 ◽  
Vol 21 (3) ◽  
pp. 287-300 ◽  
Author(s):  
Karla Monroy ◽  
Jordi Delgado ◽  
Lidia Sereno ◽  
Joaquim Ciurana ◽  
Nicolas J Hendrichs
Keyword(s):  
Selective Laser Melting ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Single Track ◽  
Cobalt Chromium ◽  
Laser Melting ◽  
Content Type ◽  
Dimensional Precision ◽  
Morphologic Characteristics ◽  
Definition Of

Purpose – Therefore, the purpose of this study is to understand the relationships between the processing parameters and the geometric form of the produced single tracks, in order to control dimensional quality in future experimentations. The quality of the deposited single track and layer is of prime importance in the selective laser melting (SLM) process, as it affects the product quality in terms of dimensional precision and product performance. Design/methodology/approach – In this paper, a vertical milling machining center equipped with an Ytterbium-fiber laser was used in the SLM experimentation to form single cobalt-chromium-molybdenum (CoCrMo) tracks. The different geometric features and the influence of the scanning parameters on these morphologic characteristics were studied statistically by means of ANOVA. Findings – Evidently, track height (h1) inaccuracy reduced in layer thicknesses between 100 and 200 μm. The re-melt depth (h2) was determined by the energy parameters, with laser power of 325-350 W and scanning speed (SS) of 66.6-83.3 mm/s being the most favorable parameters to obtain the required anchoring. Moreover, a contact angle of 117° was proposed as optimal, as it permitted an adequate overlapping region and a full densification, and, finally, an SS of 50 mm/s and a layer thickness of 250 were suggested for its development. Originality/value – The comprehension of the phenomena inherent to the process is related to the single track geometrical characteristics, which allow the definition of an optimal value for each factor for a further proposal of processing conditions that can finally derive a higher precision, wetting, density and mechanical properties.

Research on the microstructure and properties of the overhanging structure formed by selective laser melting

2017 ◽  
Vol 23 (5) ◽  
pp. 904-910 ◽  
Author(s):  
Jianfeng Sun ◽  
Zhou Yang ◽  
Yongqiang Yang ◽  
Di Wang
Keyword(s):  
Selective Laser Melting ◽  
Design Methodology ◽  
Basic Data ◽  
Theoretical Studies ◽  
Laser Melting ◽  
Content Type ◽  
Structure Matrix ◽  
Microstructure And Properties ◽  
The Future ◽  
The Matrix

Purpose This paper aims to analyze the different between matrix and overhanging structure and indicate the laws and mechanism of overhanging structure formed by selective laser melting (SLM). Design/methodology/approach This paper includes processing the matrix and overhanging structure with optimized parameters and analyzing the microstructure and properties of matrix and overhanging with OM, SEM, XRD etc. so as to analyze and reveal the laws and mechanism of overhanging structure formed by SLM. Findings The solidification of overhanging structure begins from the structure’s edge and extends to its center; the distribution of the Cr with a diameter of 250 nm in the Fe matrix is uniform; the grain in the overhanging structure is growing faster than the grain in the matrix. The overhanging structure mainly composed by austenite has no apparent layer. Moreover, the microhardness of the overhanging structure is 258.6-294.0 Hv0.3, smaller than the microhardness of the matrix which is 236.4-300.9 Hv0.3. Originality/value This paper clarifies how to manufacture overhanging structure and non-overhanging structure matrix with optimized parameters, analyzes the microstructures and compares the properties of both overhanging structure and non-overhanging structure “matrix”, so as to analyze the reasons for the forming of the overhanging structure, which in turn lauds basic data foundation for the theoretical studies in the future.

scholarly journals High Bending Strength Hypereutectic Al-22Si-0.2Fe-0.1Cu-Re Alloy Fabricated by Selective Laser Melting

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 528
Author(s):  
Chunyue Yin ◽  
Zhehao Lu ◽  
Xianshun Wei ◽  
Biao Yan ◽  
Pengfei Yan
Keyword(s):  
Selective Laser Melting ◽  
Bending Strength ◽  
Primary Silicon ◽  
Processing Parameters ◽  
Powder Materials ◽  
Laser Melting ◽  
Maximum Value ◽  
Fine Microstructure ◽  
Average Size ◽  
Al Matrix

The objective of the study is to investigate the corresponding microstructure and mechanical properties, especially bending strength, of the hypereutectic Al-Si alloy processed by selective laser melting (SLM). Almost dense Al-22Si-0.2Fe-0.1Cu-Re alloy is fabricated from a novel type of powder materials with optimized processing parameters. Phase analysis of such Al-22Si-0.2Fe-0.1Cu-Re alloy shows that the solubility of Si in Al matrix increases significantly. The fine microstructure can be observed, divided into three zones: fine zones, coarse zones, and heat-affected zones (HAZs). Fine zones are directly generated from the liquid phase with the characteristic of petaloid structures and bulk Al-Si eutectic. Due to the fine microstructure induced by the rapid cooling rate of SLM, the primary silicon presents a minimum average size of ~0.5 μm in fine zones, significantly smaller than that in the conventional produced hypereutectic samples. Moreover, the maximum value of Vickers hardness reaches ~170 HV0.2, and bending strength increases to 687.70 MPa for the as-built Al-22Si-0.2Fe-0.1Cu-Re alloys parts, which is much higher than that of cast counterparts. The formation mechanism of this fine microstructure and the enhancement reasons of bending strength are also discussed.

Deformations and stresses prediction of cantilever structures fabricated by selective laser melting process

2021 ◽  
Vol 27 (3) ◽  
pp. 453-464
Author(s):  
Lan Li ◽  
Tan Pan ◽  
Xinchang Zhang ◽  
Yitao Chen ◽  
Wenyuan Cui ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Selective Laser Melting ◽  
Thermal Distortion ◽  
Cantilever Beams ◽  
Support Structures ◽  
Laser Melting ◽  
Content Type ◽  
Two Samples ◽  
Validation Experiments

Purpose During the powder bed fusion process, thermal distortion is one big problem owing to the thermal stress caused by the high cooling rate and temperature gradient. For the purpose of avoiding distortion caused by internal residual stresses, support structures are used in most selective laser melting (SLM) process especially for cantilever beams because they can assist the heat dissipation. Support structures can also help to hold the work piece in its place and reduce volume of the printing materials. The mitigation of high thermal gradients during the manufacturing process helps to reduce thermal distortion and thus alleviate cracking, curling, delamination and shrinkage. Therefore, this paper aims to study the displacement and residual stress evolution of SLMed parts. Design/methodology/approach The objective of this study was to examine and compare the distortion and residual stress properties of two cantilever structures, using both numerical and experimental methods. The part-scale finite element analysis modeling technique was applied to numerically analyze the overhang distortions, using the layer-by-layer model for predicting a part scale model. The validation experiments of these two samples were built in a SLM platform. Then average displacement of the four tip corners and residual stress on top surface of cantilever beams were tested to validate the model. Findings The validation experiments results of average displacement of the four tip corners and residual stress on top surface of cantilever beams were tested to validate the model. It was found that they matched well with each other. From displacement and residual stress standpoint, by introducing two different support structure, two samples with the same cantilever beam can be successfully printed. In terms of reducing wasted support materials, print time and high surface quality, sample with less support will need less post-processing and waste energy. Originality/value Numerical modeling in this work can be a very useful tool to parametrically study the feasibility of support structures of SLM parts in terms of residual stresses and deformations. It has the capability for fast prediction in the SLMed parts.

Properties of aluminum metal matrix composites manufactured by selective laser melting

2021 ◽  
Vol 112 (7) ◽  
pp. 552-564
Author(s):  
Christian Felber ◽  
Florian Rödl ◽  
Ferdinand Haider
Keyword(s):  
Additive Manufacturing ◽  
Aluminum Alloys ◽  
Selective Laser Melting ◽  
Metal Matrix ◽  
High Hardness ◽  
High Strength ◽  
Laser Melting ◽  
Scanning Calorimetry ◽  
Particle Reinforcement ◽  
The Matrix

Abstract The most promising metal processing additive manufacturing technique in industry is selective laser melting, but only a few alloys are commercially available, limiting the potential of this technique. In particular high strength aluminum alloys, which are of great importance in the automotive industry, are missing. An aluminum 2024 alloy, reinforced by Ti-6Al-4V and B4C particles, could be used as a high strength alternative for aluminum alloys. Heat treating can be used to improve the mechanical properties of the metal matrix composite. Dynamic scanning calorimetry shows the formation of Al2Cu precipitates in the matrix instead of the expected Al2CuMg phases due to the loss of magnesium during printing, and precipitation processes are accelerated due to particle reinforcement and additive manufacturing. Strong reactions between aluminum and Ti-6Al-4V are observed in the microstructure, while B4C shows no reaction with the matrix or the titanium. The material shows high hardness, high stiffness, and low ductility through precipitation and particle reinforcement.

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