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Laser‐based powder bed fusion (PBF‐LB) has gained prominence in the realm of additive manufacturing of metals. This technique utilizes a laser beam to consolidate powder layers, which inherently introduces high thermal gradients and rapid cooling rates. This results in characteristic process effects, including inhomogeneities, surface roughness, anisotropy, and residual stress, which play a pivotal role in altering the fatigue properties of the manufactured components. This paper presents fatigue tests involving samples of AlSi10Mg manufactured using PBF‐LB with varying surface roughness and residual stress. An approach to predict fatigue life based on stress amplitude, residual stress, and crack size is presented, using a smooth sample as a reference. An empirical model for fatigue life prediction is developed from experimentally measured values of fatigue life, peak surface roughness, and residual stress. [ABSTRACT FROM AUTHOR]

Selective laser melting (SLM) offers an innovative manufacturing approach compared to traditional methods. It has found diverse applications in various fields, ranging from medical devices to aerospace, using a variety of metals. However, products manufactured with the metal AlSi10Mg using the SLM technique have a significant surface roughness defect. Consequently, products produced through SLM necessitate post-processing. In this study, electro-polishing was conducted on AlSi10Mg specimens manufactured at four different inclinations. Surface roughness measurements and 3D scans were performed at various time intervals to observe changes in roughness. It was observed that an increase in electro-polishing time effectively reduced surface roughness. This research provides data on post-processing for three-dimensional structures manufactured using the SLM technique. [ABSTRACT FROM AUTHOR]

In this study, AlSi10Mg samples were manufactured by laser-powder bed fusion process to explore the fracture toughness dependence on both built orientation and aging treatment. The experiments were performed on as-built and directly-aged (200 ∘ C/4 h) conditions, with the latter revealed to be a valuable treatment for improving fracture toughness. A comprehensive investigation involving detailed microstructural analysis, grain-orientation mapping, and crack-tip strain measurements was conducted to investigate the mechanisms governing the material behavior. The results revealed that specimens subjected to direct aging display higher toughness, thereby enhancing the fracture resistance of AlSi10Mg. Moreover, a considerable variation in fracture toughness values was observed for the different printing orientations, indicating the existence of manufacturing-induced anisotropy. The findings highlight that this anisotropy mainly correlates with the distinctive microstructure induced by the additive manufacturing process. In particular, this study focuses on the different preferential crack paths dictated by the melt pool boundaries orientation respective the crack propagation direction. A substantial reduction in fracture toughness was observed when the crack propagates along the melt pool boundaries. [ABSTRACT FROM AUTHOR]

The notch effect significantly influences the fatigue response of components and is particularly relevant for parts produced with additive manufacturing (AM) processes, characterized by complex geometries and possible geometric discontinuities inducing local and critical peak stresses. Moreover, the low surface quality, as well as manufacturing defects and residual stresses, interacts with the local peak stress induced by geometric discontinuities, complicating the assessment of the notch effect for AM parts and requiring extensive experimental fatigue investigations. In the present paper, the notch sensitivity of as‐built AlSi10Mg specimens produced with the laser beam powder bed fusion in the Very High Cycle Fatigue regime is investigated. Ultrasonic fatigue tests up to 109 cycles have been carried out on rectangular bars and rectangular bars with a central through‐thickness hole. The notch effect has been found to significantly affect the fatigue response of the investigated AlSi10Mg specimens, with surface defects having a main role and pointing out the influence of the surface quality on the crack formation. [ABSTRACT FROM AUTHOR]

In this article, the evolution of microstructural characteristics of selectively laser-melted AlSi10Mg alloy subjected to equal channel angular pressing (ECAP) is investigated. The microstructures were analyzed in detail using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission Kikuchi diffraction (TKD), and transmission electron microscopy (TEM). A heterogeneous ultrafine-grained microstructure was produced after one ECAP pass at 100 °C. This microstructure was composed of Al/Si cells and sub-micrometer grains. The grains were refined by conventional dislocation processes; however, evidence of dynamic recrystallization was also documented. Furthermore, it was revealed that the Al/Si cells contribute significantly to grain refinement. EBSD/TKD investigations showed that cell misorientation increased after ECAP processing, resulting in an increased fraction of grains with very low misorientation angles. [ABSTRACT FROM AUTHOR]

To enhance the energy absorption characteristics of the energy-absorbing structure in metal alloy 3D printing, various heat treatment conditions were studied on the 3D printed hourglass multi-cellular energy-absorbing structure (HTMEAS). The results reveal that as the annealing temperature rises, the structural morphology of the α-Al+Si phase in AlSi10Mg alloy undergoes alterations, particularly when the annealing temperature remains below 300°C. After heat treatment, the HTMEAS can contract layer by layer along the gradient and undergo controllable and orderly deformation. The maximum energy absorption, displacement, and peak force reached 758 J, 30 mm, and 30 kN, respectively.These values represent a significant enhancement of 146.8 %, 157.8 %, and 50 % compared to those without heat treatment, showcasing commendable mechanical properties. This advancement establishes a solid theoretical framework and assurance for the future development and refinement of 3D printing energy-absorbing structures. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of Nanjing University of Aeronautics & Astronautics is the property of Editorial Department of Journal of Nanjing University of Aeronautics & Astronautics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To enhance the energy absorption characteristics of the energy-absorbing structure in metal alloy 3D printing, various heat treatment conditions were studied on the 3D printed hourglass multi-cellular energy-absorbing structure (HTMEAS). The results reveal that as the annealing temperature rises, the structural morphology of the α-Al+Si phase in AlSi10Mg alloy undergoes alterations, particularly when the annealing temperature remains below 300°C. After heat treatment, the HTMEAS can contract layer by layer along the gradient and undergo controllable and orderly deformation. The maximum energy absorption, displacement, and peak force reached 758 J, 30 mm, and 30 kN, respectively.These values represent a significant enhancement of 146.8 %, 157.8 %, and 50 % compared to those without heat treatment, showcasing commendable mechanical properties. This advancement establishes a solid theoretical framework and assurance for the future development and refinement of 3D printing energy-absorbing structures.

The additive manufacturing method offers a number of advantages such as rapid prototyping, design flexibility and unique part production. However, compared to traditional production methods, the production volume is limited. Therefore, to meet large-volume production demands, additive manufacturing is not as effective as traditional methods. In order to overcome this disadvantage, scientists are conducting research on the assembly of parts produced by additive manufacturing method. This study focuses on investigating the MIG (Metal Inert Gas) weldability of AlSi10Mg SLM (Selective Laser Melting) plate to AlSi10Mg SLM plate and subsequently optimizing the welding parameters for welding zone hardness and tensile strength. The most suitable parameters obtained in the hardness optimization of the weld zone were determined as 20.6 V, 120 A, 5356 (AlMg5). The most suitable parameters for tensile strength optimization were determined as 20.6 V, 110 A and 4047 (AlSi12). In addition to all these, 4047 filler material is thought to be the most suitable weld filler material for this study, as it provides the best tensile strength performance, offers acceptable weld zone hardness and is relatively easily accessible in the market. [ABSTRACT FROM AUTHOR]

In this study, the microstructure, hardness, tensile strength, and dry wear properties of the cast AlSi10Mg alloy as well as the effects of processing parameters on the oxidation behavior of this alloy were investigated. In this context, AlSi10Mg (wt%) alloy was produced by gravity die casting method, and then, air cooling, quenching, and T6 treatment were applied. The microstructure of the alloy was investigated using an optical microscope, SEM, and EDS. Additionally, thermogravimetric analysis (TGA) was used to determine the effect of processing parameters on the oxidation behavior of the samples. The friction and wear properties of the alloy were investigated using a ball-on-disk wear test device. It was founded that the as-cast AlSi10Mg alloy's microstructure contained phases of α(Al), Si, and β-Mg2Si. It has been observed that the microstructure of the cast AlSi10Mg alloy gradually turns into a spherical form when quenching and air-cooling heat treatments are applied. Also, T6 heat treatment led to further spheroidization of Si particles, formation of β-Mg2Si precipitates, and elimination of the Chinese script morphology of the β-Mg2Si phase. It was observed that the yield strength of the AlSi10Mg alloy in the as-cast state decreased negligibly compared to the air-cooled state, while there was an increase of up to 70% in the aging-treated condition. The results show that the tensile strength of the as-cast AlSi10Mg alloy increased by 115% after aging. Additionally, it was found that the AlSi10Mg alloy's wear resistance increased with the aging process. [ABSTRACT FROM AUTHOR]

Selective laser melting (SLM) technology is widely used in various fields for manufacturing high-precision and complex parts. However, SLMed parts still exhibit some microstructural defects. The remelting strategy provides a new approach for defect elimination in SLM process, named as selective laser remelting (SLRM). In this study, the effects of remelting strategy on the melt pool were revealed through a finite element model. The porosity, microstructure, surface roughness, microhardness and tensile behavior of the specimens were also evaluated. The links between the formation mechanism of the melt pool and various experimental results were explored. The simulation results showed that the SLRMed melt pool had a significantly lower temperature and a shorter liquid phase time. The experimental results demonstrated that the remelting strategy effectively reduced the porosity, improved the density of the specimens, and provided a finer microstructure. The remelting strategy effectively reduced the surface roughness of the top surface of the specimens, while slightly adversely affecting the surface roughness of the side surface. Additionally, the microhardness and tensile properties of the specimens increased correspondingly due to the finer microstructure formed inside the SLRMed melt pool. These findings contribute to a better understanding and application of the remelting strategy for producing high-quality parts.

Plate-based lattice structures are an emerging category of mechanical metamaterials with exceptional mechanical performance. In this work, plate-based SCFCC metamaterials of AlSi10Mg with various relative densities are fabricated by laser powder bed fusion (LPBF). Circular holes are strategically designed and placed at the center of each non-load-bearing face for residual powder removal. Quasi-static compression experiments and numerical simulations are performed to investigate their mechanical performance and deformation mechanisms. Results indicate that the elastic modulus of SCFCC metamaterials decreases by 3.5% with the presence of 0.9 mm diameter holes, while increasing the hole size shows negligible impact on the elastic modulus. The novel plate-based SCFCC structure exhibits superior mechanical properties and enhanced energy absorption capacity concerning conventional high-stiffness truss-based and shell-based counterparts. The improvement, at the relative density of 0.2, can be observed in terms of elastic modulus (around 50%), peak compressive strength (around 300%), energy absorption capacity (around 400% or 200%). When increasing the relative density from 0.2 to 0.5, plate-based SCFCC metamaterial still maintains superior mechanical performance while the gaps between SCFCC and its counterparts narrow down gradually owing to the loss of structural features. Moreover, mechanical characteristics and coefficients of three Gibson and Ashby analytical equations are determined. This work proposes a novel type of plate-based structure with both exceptional mechanical performance and good additive manufacturability, which opens a new avenue for the design of lightweight mechanical metamaterials.

Manufacturing through powder-bed fusion laser-beam (PBF-LB) enables innovative part design strategies, facilitating weight reduction, and capitalizing on the metallurgical conditions developed during the manufacturing of designed alloys. Consequently, Al-based light alloys hold enormous potential for reducing fuel consumption in the transport industry. Fabricating such small features has a significant impact on heat dissipation, thereby affecting microstructure, porosity, and, consequently, mechanical properties. This study proposes the use of near-net shape miniaturized tensile specimens in both horizontal and vertical orientations to characterize Al-Mg-Sc-Zr, commercially known as Scalmalloy®, and AlSi10Mg, two aluminum alloys typically employed in PBF-LB. The size and distribution of both grains and pores were analyzed and compared, with Al-Mg-Sc-Zr exhibiting a more competitive set of properties compared to AlSi10Mg. This difference also influences mechanical properties. Al-Mg-Sc-Zr demonstrated double the Ultimate Tensile Strength (UTS) of AlSi10Mg (450 MPa versus 225 MPa) and higher hardness values (142 HV30 versus 75 HV30), with similar elongation in both alloys (approximately 12–16%), owing to its fine microstructure and low porosity of the near-net shape miniaturized tensile specimens. Neither material exhibited any form of anisotropy. In-situ SEM tensile tests were conducted to monitor damage evolution, allowing continuous observation of crack nucleation and propagation through imperfections typically encountered in PBF-LB. Despite differences in static strength, the fracture surfaces of the samples displayed a ductile behavior in both materials.

The detection of defects in aluminium alloys using eddy current testing (ECT) can be restricted by higher electrical conductivity. Considering the occurrence of discontinuities during the selective laser melting (SLM) process, checking the ability of the ECT method for the mentioned purpose could bring simple and fast material identification. The research described here is focused on the application of three ECT probes with different frequency ranges (0.3–100 kHz overall) for the identification of artificial defects in SLM aluminium alloy AlSi10Mg. Standard penetration depth for the mentioned frequency range and identification abilities of used probes expressed through lift-off diagrams precede the main part of the research. Experimental specimens were designed in four groups to check the signal sensitivity to variations in the size and depth of cavities. The signal behavior was evaluated according to notch-type and hole-type artificial defects' presence on the surface of the material and spherical cavities in subsurface layers, filled and unfilled by unmolten powder. The maximal penetration depth of the identified defect, the smallest detectable notch-type and hole-type artificial defect, the main characteristics of signal curves based on defect properties and circumstances for distinguishing between the application of measurement regime were stated. These conclusions represent baselines for the creation of ECT methodology for the defectoscopy of evaluated material. [ABSTRACT FROM AUTHOR]

Process monitoring systems, e.g., systems based on photodiodes, could be used in laser-based powder bed fusion (PBF-LB/M) to measure various process parameters and process signatures to eventually allow for a local, detailed analysis of the produced parts. Here, simple statements only concerning the occurrence of defects in parts are sufficient in many cases, especially with respect to industrial application. Therefore, a pragmatic approach to rapidly infer the occurrence of defects and their types based on in situ data obtained by commercially available process monitoring systems is introduced. In this approach, a color distribution in form of a histogram is determined for each produced part using layer-wise screenshots of the visualized data provided by the monitoring software. Assessment of the histograms of AlSi10Mg samples, which were processed with different parameter combinations, revealed characteristics depending on the prevailing defect types. These characteristics enable the prediction of the occurring defect types without the necessity to apply conventional downstream testing methods, and thus, a straightforward separation of parts with good quality from defective components. Since the approach presented uses the data visualization of the monitoring software, it can be used even when direct access to the raw data is not provided by the machine manufacturer. [ABSTRACT FROM AUTHOR]

Due to the large design freedom of additive manufacturing (AM), components manufactured by laser powder bed fusion (PBF-LB) possess a high lightweight potential, which increases the importance of PBF-LB for applications in the automotive, aviation and aerospace industries. The typically high surface roughness of PBF-LB parts leads to a significant reduction in fatigue strength. Therefore, a finishing process for improving the surface roughness of complex PBF-LB parts is required. Stream finishing represents such a process. In a first step, surface roughness evolution and abrasion rates were measured for specimens manufactured with PBF-LB at different stages of the finishing process. In a second step, fatigue specimens were manufactured, machined both by turning and stream finishing, and tested by rotating bending fatigue tests. To evaluate crack initiation and propagation, the fracture surfaces were examined by scanning electron microscopy. The microstructure and microhardness near the surface were investigated to assess the influence of the surface layer on the fatigue behaviour. Stream finishing proved to be a suitable finishing process, as the specimens exhibited very low surface roughness and improved fatigue behaviour compared to turned specimens, especially for lower stresses. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the indentation behavior of thin AlSi10Mg specimens manufactured using Selective Laser Melting (SLM) in the as-built condition along with two post-treatments, namely solution heat treatment and artificial aging. Four different thicknesses of 1.0 mm, 1.5 mm, 2 mm, and 2.5 mm of SLM specimens, with the different post-treatments, underwent standardized Rockwell hardness tests using a spherical indenter to determine their hardness values and assess the impression using a stereo microscope and scanning electron microscope (SEM). The as-built specimens showed a trend of smaller indentation depths with increasing specimen thickness, and finally creased with 0.1547 mm depth at 2.5 mm. However, the post-treatments altered the behavior of the specimens to a certain degree, giving larger experimental indentation depths of 0.2204 mm, 0.1962 mm, and 0.1798 mm at 1.0 mm, 1.5 mm, and 2.5 mm thickness, respectively, after solution heat treatment. Artificial aging showed a general decrease in indentation depth with increasing specimen thickness in contrast to solution treatment, and resulted in depths of 0.1888 mm and 0.1596 mm at 1.0 mm and 2.5 mm thickness. Furthermore, a material numerical model was made using stress–strain data on ANSYS Workbench to develop a predictive model for the indentation behavior of the specimens in contrast to experimentation. Under multi-linear isotropic hardening, the Finite Element Analysis (FEA) simulation produced indentation geometry with an average accuracy of 95.4% for the artificial aging series. [ABSTRACT FROM AUTHOR]

The effect of iso‐thermal heat treatments on powder bed fusion–laser beam (PBF–LB) AlSi10Mg alloy has been studied; however, an extensive process–property relationship evaluation has not yet been undertaken. In addition, the coarsening of eutectic Si from low‐to‐high (200–500 °C) temperature heat treatment has not been investigated systematically. Therefore, AlSi10Mg alloy is heat‐treated at 200, 300, 400, and 500 °C for holding times ranging from 0.5 to 32 h. Uniaxial tensile and hardness tests are conducted, and the microstructure is characterized. A unique approach is adopted for estimating Si solubility where 200 °C heat‐treated microstructure data to estimate solute trapping due to the high cooling rate in the as‐fabricated state. It is observed that increasing the heat‐treatment temperature and time reduces the strength and strain‐hardening rate but increases the tensile elongation up to 400 °C heat treatment. At 500 °C, the yield strength increases, and the elongation reduces compared with the 400 °C heat treatment owing to the refined Fe containing dispersoid formation at 500 °C. The important outcome of this study is heat‐treatment process–property contour maps that are useful for fine‐tuning the mechanical properties of PBF–LB AlSi10Mg alloy for industrial prototyping application. [ABSTRACT FROM AUTHOR]

A new hydrothermal hot isostatic pressing (HHIP) approach, involving hydrothermal water conditions and no usage of inert gas, was hypothesized and tested on 3D-printed Al-10%Si-0.3%Mg (%Wt) parts. The aluminum-based metal was practically inert at the applied HHIPing conditions of 300–350 MPa and 250–350 °C, which enabled the employment of a long (6–24 h) HHIP treatment with hardly any loss of material (the overall loss due to corrosion was mostly <0.5% w/w). Applying the new approach on the above-mentioned samples resulted in an 85.7% reduction in the AM micro-pores, along with a 90.8% reduction in the pores' surface area at a temperature of 350 °C, which is much lower than the 500–520 °C applied in common argon-based aluminum HIPing treatments, while practically maintaining the as-recieved microstructure. These results show that better mechanical properties can be expected when using the suggested treatment without affecting the material fatigue resistance due to grain growth. The proof of concept presented in this work can pave the way to applying the new HHIPing approach to other AM metal parts. [ABSTRACT FROM AUTHOR]

Additively manufactured lattice structures are extensively utilized because of their unique characteristics, including lightweight design, high energy absorption capabilities, and exceptional specific strength. This study focuses on accurately simulating the dynamic mechanical behavior of AlSi10Mg lattice structures produced using selective laser melting (SLM). A series of experimental studies has been conducted to establish the parameters of the J–C hardening and damage model for additively manufactured AlSi10Mg alloys. The lattice structures, featuring face-centered cubic (FCC) and diamond topologies with a 25% designed relative density, underwent scanning electron microscopy (SEM) for geometrical precision assessment. Dynamic compressive behavior was investigated via split Hopkinson pressure bar (SHPB) tests. Numerical simulations in Ls-Dyna, utilizing the identified J–C parameters, were employed to replicate SHPB tests. Findings indicate that the specific strength and the specific energy absorption values of FCC lattice samples have higher than those of diamond samples at strain rates of 750 and 1100 s−1. While the overall strains and deformation modes were well predicted by numerical analyzes, a deeper insight into local stress concentrations under dynamic loads was achieved. Consequently, the obtained J–C model parameters offer valuable insight into characterizing the dynamic behavior of AlSi10Mg lattice structures produced by SLM. [ABSTRACT FROM AUTHOR]

Metal additive manufacturing technologies, such as Laser Powder-Bed Fusion, often rate as sustainable due to their high material efficiency. However, there are several drawbacks that reduce the overall sustainability and offer potential for improvement. One such drawback is waste emerging from the process. These smoulder particles form when the laser hits the powder-bed surface, are blown away from the part by the shielding gas stream and accumulate on the edge of the build chamber. Usually, smoulder does not contribute to the circular reuse of powder that was part of the powder-bed but was not integrated into a part. Instead, it marks an end-of-life state of powder. Significant amounts of smoulder accumulate depending on the irradiated area or the build volume in one job, respectively. This results in the waste of powder that was produced with low energy efficiency. This study investigates the question of whether smoulder can transform from waste to resource via common powder characterization methods and first build jobs using processed smoulder. The investigation of process-relevant powder properties like apparent density and flowability showed no significant difference between virgin powder and smoulder. Sample characterization indicated that neither porosity, surface quality nor mechanical properties deteriorate when samples contain about 50% smoulder. This allows for the reuse of smoulder in terms of powder characterization and part quality. [ABSTRACT FROM AUTHOR]

In this study, corrosion inhibition of the additively manufactured AlSi10Mg was investigated in 3.5% NaCl solution with the addition of 1% and 3% NH4 NO3 . The potentiodynamic polarization and electrochemical impedance spectroscopy tests were performed in order to reveal the corrosion behavior of the AlSi10Mg. The corrosion inhibition behavior of the AlSi10Mg was determined by analyzing the Tafel curves, phase angle/frequency curves and equivalent circuit results. Moreover, microstructures of the produced sample and corroded surfaces were investigated with light metal microscopy. It was stated that the corrosion rate value of the AlSi10Mg is reduced with the presence of NO3 - in 3.5% NaCl solution. On the other hand, the surface/solution interaction was reduced by adding NH4 NO3 into 3.5% NaCl solution. It can be clearly emphasized that using 3% NH4 is quite effective in improving the corrosion behavior of AlSi10Mg in 3.5% NaCl. [ABSTRACT FROM AUTHOR]3 is quite effective in improving the corrosion behavior of AlSi10Mg in 3.5% NaCl. [ABSTRACT FROM AUTHOR]

A new approach is proposed that identifies three different zones of the Si-rich network structure (the cellular structure) in laser powder bed fused (LPBF) AlSi10Mg alloy, based on the variation in morphology, grain growth transition, and melt pool solidification conditions. The three identified zones are denoted in the present work as the liquid solidification zone (LSZ), the mushy solidification zone (MSZ), and the heat affected zone (HAZ). The LSZ is the result of liquid–solid transformation, showing small planar growth at the boundary and large cellular growth in the center, while the MSZ is related to a semisolid reaction, and the HAZ arises from a short-time aging process. The boundary between the LSZ and MSZ is identified by the change of grain growth direction and the Si-rich network advancing direction. The boundary between MSZ and HAZ is identified by the start of the breakdown of the Si-rich network. In addition, it is found that the fracture is generated in and propagates along the HAZ during tensile tests. [ABSTRACT FROM AUTHOR]

A promising method for additive manufacturing that makes it possible to produce intricate and personalized parts is selective laser melting (SLM). However, the mechanical properties of as-corroded SLM parts are still areas of concern. This research investigates the mechanical behavior of SLM parts that are exposed to a saline environment containing a 3.5% NaCl solution for varying lengths of time. The exposure times chosen for this study were 10 days, 20 days, and 30 days. The results reveal that the tensile strength of the parts is significantly affected by the duration of exposure. Additionally, the study also examined the influence of porosity on the corrosion behavior of the parts. The analysis included studying the mass loss of the parts over time, and a regression analysis was conducted to analyze the relationship between exposure time and mass loss. In addition, the utilization of scanning electron microscopy (SEM) and X-ray photo spectroscopy (XPS) techniques yielded valuable insights into the fundamental mechanisms accountable for the observed corrosion and mechanical behavior. It was found that the presence of corrosion products (i.e., oxide layer) and pitting contributed to the degradation of the SLM parts in the saline environment. This research emphasizes the importance of considering part thickness in the design of SLM components for corrosive environments and provides insights for enhancing their performance and durability. [ABSTRACT FROM AUTHOR]

The AlSi10Mg alloy samples were successfully prepared by laser powder bed fusion（LPBF）. The effects of three kinds of heat treatment process，namely 130 ℃/4 h aging treatment，236 ℃/10 h annealing treatment，and 540 ℃/1 h solid solution treatment on the microstructure of the AlSi10Mg samples were investigated. After heat treatment，the evolution of coefficient of thermal expansion（CTE） and thermal conductivity of the AlSi10Mg alloy in the temperature range from room temperature to 400 ℃ was examined. The results show that spherical Si particles are precipitated within the aluminum matrix，while the complete network-like eutectic silicon structure is retained after aging treatment. After annealing，the network-like silicon structure is disappeared completely，and spherical Si particles are uniformly distributed within the matrix. After solution treatment，large blocky Si particles with the sizes from 1 μm to 3 μm appear. The thermal properties of the AlSi10Mg alloy have been improved significantly after heat treatment compared to the as-printed state. In particular，the CTE of alloy subjected to annealing is 1.64×10−5 ℃−1 to 2.1×10−5 ℃−1 within the temperature range from room temperature to 400 ℃，the average thermal conductivity is 179.6 W·m−1·K−1，the performance is superior to ageing and solution treatments.

Metal additive manufacturing technologies, such as Laser Powder-Bed Fusion, often rate as sustainable due to their high material efficiency. However, there are several drawbacks that reduce the overall sustainability and offer potential for improvement. One such drawback is waste emerging from the process. These smoulder particles form when the laser hits the powder-bed surface, are blown away from the part by the shielding gas stream and accumulate on the edge of the build chamber. Usually, smoulder does not contribute to the circular reuse of powder that was part of the powder-bed but was not integrated into a part. Instead, it marks an end-of-life state of powder. Significant amounts of smoulder accumulate depending on the irradiated area or the build volume in one job, respectively. This results in the waste of powder that was produced with low energy efficiency. This study investigates the question of whether smoulder can transform from waste to resource via common powder characterization methods and first build jobs using processed smoulder. The investigation of process-relevant powder properties like apparent density and flowability showed no significant difference between virgin powder and smoulder. Sample characterization indicated that neither porosity, surface quality nor mechanical properties deteriorate when samples contain about 50% smoulder. This allows for the reuse of smoulder in terms of powder characterization and part quality.

Lightweight lattice structures can have their mechanical properties and failure modes predicted through computer simulation. This approach has great potential for use in aerospace, the automotive industry, and defense equipment. However, due to the limitations of the LPBF process, fabricated lattice structures contain internal defects that affect the compression response, which leads to high-level errors in finite element method (FEM) predictions and experimental results. Thus, in this paper, a finite element model considering the effect of pore defects was built by using finite element simulation in connection with the Gurson-Tvergaard-Needleman (GTN) damage model to investigate the compressive behavior and mechanical response of the body-centered cubic lattice structure of AlSi10Mg alloys prepared by the LPBF process. A three-dimensional reconstruction of the molded BCC lattice structure was performed by computed tomography (CT) to obtain the structure's distribution and shape of micropores. Using a combination of simulation (FEM-GTN) and experimentation, the effects of process parameters on the compressive properties and mechanical behavior of the BCC lattice structure during quasi-static compression were investigated. The results show that the FEM simulation results corrected by the GTN damage model are in better accordance with the experimental results (the error rate is reduced by more than 10 %) compared to the FEM simulation results without considering the influence of the pore defects, which proves the higher accuracy of the FEM-GTN simulation model. This work provides a reference for the property prediction and fabrication of high-performance, lightweight lattice structures.

Shielding gas, metal vapors, and gases trapped inside powders during atomization can result in gas porosity, which is known to degrade the fatigue strength and tensile properties of components made by laser powder bed fusion additive manufacturing. Post-processing and trial-and-error adjustment of processing conditions to reduce porosity are time-consuming and expensive. Here, we combined mechanistic modeling and experimental data analysis and proposed an easy-to-use, verifiable, dimensionless gas porosity index to mitigate pore formation. The results from the mechanistic model were rigorously tested against independent experimental data. It was found that the index can accurately predict the occurrence of porosity for commonly used alloys, including stainless steel 316, Ti-6Al-4V, Inconel 718, and AlSi10Mg, with an accuracy of 92%. In addition, experimental data showed that the amount of pores increased at a higher value of the index. Among the four alloys, AlSi10Mg was found to be the most susceptible to gas porosity, for which the value of the gas porosity index can be 5 to 10 times higher than those for the other alloys. Based on the results, a gas porosity map was constructed that can be used in practice for selecting appropriate sets of process variables to mitigate gas porosity without the need for empirical testing. [ABSTRACT FROM AUTHOR]

The precision of lightweight components produced during machining of aluminium alloy is critical as a reason of its high chemical reactivity to the tool metal when cutting. Mineral-based cutting fluids (CFs) used in the manufacturing industry pollute the environment and offer adequate health risks to the operators; it is vital to develop environmentally friendly machining technologies. As a corollary, vegetable oil (VO) must be used to replace mineral oil to avoid pollution. In recent decades, VO produced from raw edible sources is a reliable source for greener CF. Toxic fumes and skin irritations caused by conventional CFs are all avoided when using VO in machining. In this research, an additively manufactured AlSi10Mg specimen was machined with distinct coolants to enhance the surface trait. The mechanical performance such as tensile, hardness and wear strength were investigated to prove that the 90° oriented AlSi10Mg parts show better strength. Further, the machining of 90° oriented AlSi10Mg parts was performed to examine certain issues such as surface morphology, flank wear and cutting temperature using different cooling regimes (flood and MQL with soybean oil). As a result of heat generation in the cutting zone, the surface deteriorates and the cutter needs to be replaced often. The MQL with VO minimises the heat generated at the cutting region and lessened the roughness to 25–42% and temperature to 24–39% with flood coolant. Additionally, the microstructure under MQL cutting produced fine grains. The desirability function was employed to find the ideal cutting condition for sustainable manufacturing. [ABSTRACT FROM AUTHOR]

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AlSi10Mg porous protective structure often produces different damage forms under compressive loading, and these damage modes affect its protective function. In order to well meet the service requirements, there is an urgent need to comprehensively understand the mechanical behavior and response mechanism of AlSi10Mg porous structures under compressive loading. In this paper, AlSi10Mg porous structures with three kinds of volume fractions are designed and optimized to meet the requirements of high-impact, strong-energy absorption, and lightweight characteristics. The mechanical behaviors of AlSi10Mg porous structures, including the stress–strain relationship, structural bearing state, deformation and damage modes, and energy absorption characteristics, were obtained through experimental studies at different loading rates. The damage pattern of the damage section indicates that AlSi10Mg porous structures have both ductile and brittle mechanical properties. Numerical simulation studies show that the AlSi10Mg porous structure undergoes shear damage due to relative misalignment along the diagonal cross-section, and the damage location is almost at 45° to the load direction, which is the most direct cause of its structural damage, revealing the damage mechanism of AlSi10Mg porous structures under the compressive load. The normalized energy absorption model constructed in the paper well interprets the energy absorption state of AlSi10Mg porous structures and gives the sensitive location of the structures, and the results of this paper provide important references for peers in structural design and optimization. [ABSTRACT FROM AUTHOR]

The low deposition efficiency in directed energy deposition (DED) has prompted the reuse of powders that do not fuse to the builds to make additive manufacturing more sustainable. It is unknown, however, how the properties of the powder and deposited parts change as powders are continuously reused. In this study, AlSi10Mg was investigated for five deposition cycles in DED. Exposing AlSi10Mg powder to DED conditions changes the morphology, size, and flowability. The mechanical properties of AlSi10Mg DED parts decreased after the feedstock powder was reused one time. Notably, no additional significant changes were observed when the powder was further reused. [ABSTRACT FROM AUTHOR]

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During powder-bed fusion (PBF), the irradiated material causes undesirable thermal stresses while experiencing large temperature oscillations over a rapid period. This requires the components produced by this technique to undergo thermal treatment. The characteristics of additively manufactured materials, which are rapid heating and cooling, do not accept conventional methods, such as thermal treatment, that alleviate stress for the removal of thermal stresses. In this research, the thermal treatment of age hardening is explored, in which AlSi10Mg is subjected to lower temperatures for longer periods of time. Other samples were thermally treated at 300 °C and 400 °C for various hours and quenched in ice water. This is conducted to identify the acceptable temperature and conditions that will improve the properties after thermal treatment without jeopardising other properties of the material and to investigate the effects of the thermal treatment profiles on the microstructural and mechanical characteristics of the AlSi10Mg samples. [ABSTRACT FROM AUTHOR]

Laser powder bed fusion (LPBF) process has a great ability to produce complex AlSi10Mg 3D components with uncommon degrees of freedom for broad span of applications in different industries. Presence of the microstructural imperfections such as porosity, dependent on the parameters of the process can be detrimental to the printed products for different engineering applications. Parameters of the process and different post-processing heat and surface treatments are recognized for decrease of the occurrence of microstructural defects and for the improvement of the mechanical properties. The influence of laser power by applying four different laser speeds at one layer thickness with a constant hatch distance, on the microstructure and microhardness of the AlSi10Mg alloy was examined in this paper. The goal of the research was to determine whether increasing the laser speed will have a significant impact on the change in microstructure and the appearance of porosity in the tested samples. [ABSTRACT FROM AUTHOR]

The wear surface morphology of AlSi10Mg specimens, originally manufactured using selective laser melting (SLM), has been analyzed in the context of exposure to heat from gas flames. The first stage of the experimental work included the performance of surface heat-exposure on SLM-prepared specimens through oxyacetylene gas welding. Gas welding was utilized with three different flames, namely; reducing, neutral, and oxidizing on the as-built specimens of SLM. The post-surface-treated specimens were subjected to pin-on-disk wear testing against fixed parameters. After the performance of wear testing at two different radii, the mass loss of each of the four types of specimens was calculated including the three specimens exposed to heat along with the as-built specimens. The results showed that the maximum amount of mass losses at 24 mm and 30 mm radii belongs to the neutral flame specimens and the least was for the as-built condition specimens. Upon analysis, the heat-exposure specimens through all three types of gas flames resulted in an increase in the amount of mass in contrast to the as-built specimens. Moreover, the morphologies of the developed wear tracks at surfaces were examined using the scanning electron microscope (SEM) for the understating of the mechanism. [ABSTRACT FROM AUTHOR]

Low performance is considered one of the main drawbacks of laser powder bed fusion (LPBF) technology. In the present work, the effect of the AlSi10Mg powder layer thickness on the laser melting process was investigated to improve the LPBF building rate. A high-fidelity simulation of the melt pool formation was performed for different thicknesses of the powder bed using the Kintech Simulation Software for Additive Manufacturing (KiSSAM, version cd8e01d) developed by the authors. The powder bed after the recoating operation was obtained by the discrete element method. The laser energy deposition on the powder particles and the substrate was simulated by ray tracing. For the validation of the model, an experimental analysis of single tracks was performed on two types of substrates. The first substrate was manufactured directly with LPBF technology, while the second was cast. The simulation was carried out for various combinations of process parameters, predominantly with a high energy input, which provided a sufficient remelting depth. The calculations revealed the unstable keyhole mode appearance associated with the low absorptivity of the aluminum alloy at a scanning speed of 300 mm/s for all levels of the laser power (325–375 W). The results allowed formulating the criteria for the lack of fusion emerging during LPBF with an increased layer thickness. This work is expected to provide a scientific basis for the analysis of the maximum layer thickness via simulation to increase the performance of the technology. [ABSTRACT FROM AUTHOR]

The scientific community has been intensively studying how to improve the level of surface roughness on 3D-printed parts, particularly metallic parts made using the selective laser melting (SLM) technique. Various research papers on this subject have revealed that accurate surface roughness data can be generated using several methods that are, in fact, not cost-effective. For this reason, the finishing processes are an integral part of the overall production, especially for those components where the primary concern is not only appearance but also functional properties (e.g., lower friction, reduced noise, etc.). This work deals with the measurement of the surface roughness of tumbled parts produced with SLM after surface treatment with centrifugal and vibratory methods. Tumbling was performed with ceramic, plastic, and porcelain mediums. At the end, there is an evaluation of the measurement data based on the required surface roughness of the components. [ABSTRACT FROM AUTHOR]

Understanding the machinability of additively manufactured composite materials is crucial for efficient manufacturing. The study aimed to evaluate the machinability of the composite material (AlSi10Mg + Niobium carbide (NbC)) using the Electro-discharge machining (EDM) process and to investigate the influence of different printing orientations on the EDM process. The Plackett–Burman design was initially employed to determine the significant EDM parameters. Subsequently, the Box–Behnken Design was followed to obtain the optimal settings on the EDM setup. The validation experiment based on the composite desirability approach confirmed the maximum material removal rate (MRRmax) and minimum tool wear rate (TWRmin). The identified configuration of 3 wt. % NbC reinforcement in AlSi10Mg, printed in the 0° orientation, exhibited the best performance in MRRmax: 146.43 mg/min, TWRmin: 0.00072 mg/min, and surface finish of 2.813 µm. These findings enhance the understanding of composite machinability and can assist in optimizing the EDM process for advanced materials. [ABSTRACT FROM AUTHOR]

Direct metal laser sintering (DMLS) has revolutionised manufacturing by making elaborate and customised shapes feasible. This additive manufacturing method creates alloys from customised metal powders, creating intricate and sophisticated components. DMLS uses partly melted powder particles, hence sintering factors like laser energy density, hatch distance, and scanning speed are important. Manufacturers may improve mechanical qualities including microhardness, surface roughness, and microstructure by carefully optimising these parameters, which will promote additive manufacturing. AlSi10Mg composite material has high mechanical strength, corrosion resistance, and low density. We investigate the additive manufacturing potential of AlSi10Mg, taking into account its benefits. Thus, optimising sintering settings is necessary to study AlSi10Mg composite mechanical properties. Based on this paper's discussion of laser density of 370 and 390 W/s, this optimisation technique improves material characteristics. This study advances additive manufacturing by improving our knowledge of AlSi10Mg composite component mechanical characteristics, surface roughness, and microstructure via optimised sintering process parameters. The results seek to improve production, reduce material post-processing, and increase product quality. [ABSTRACT FROM AUTHOR]