The importance of powders on the final part properties in Selective Laser Melting (SLM) process is well-known. At the moment, gas atomization is used to produce powders for the SLM process. However, there is a growing interest in investigating the use of the less expensive water atomization process. In this work, water and gas atomized powders were used as feedstock to produce specimens with an industrial

Manufacturing of functional (ready to use) parts with the powder bed fusion method has seen an increase in recent times in the field of aerospace and in the medical sector. Residual stresses (RS) induced due to the process itself can lead to defects like cracks and delamination in the part leading to the inferior quality of the part. These RS are one of the main reasons preventing the process from

The design of self-supporting structures is critical for the selective laser melting (SLM)-based 3D printing techniques. However, the control of the overhang feature conflicts with the mechanical performance of the structure. This paper proposes an approach to achieve the self-supporting structural design to facilitate the SLM process. Printable overhang heights of samples under various overhang angles

This work models the square array mesostructure found in fused filament fabrication parts using an orthotropic constitutive model and derives closed-form expressions for all nine effective elastic constants. The periodic void shape is modeled using a four point hypotrochoid curve with a single shape parameter that controls the sharpness of the points. In-plane elastic constants (Eyy, Ezz, vyz, Gyz)

In this paper, a novel hybrid heat source model is developed considering the different absorption mechanisms for porous and dense state materials, and an effective absorptivity is adapted to the proposed model to analyze the melting mode transition. The proposed model can predict the melt pool characteristics including the melt pool dimensions and the melting modes in the selective laser melting (SLM)

Multi-material additive manufacturing, as an additive manufacturing technique with the ability to simultaneously print multiple materials, is widely used in generating composites with multi-colors, complex multi-material structures, and materials with gradient properties. It also becomes a powerful tool in the study of structure-property relationship in composites, mechanical metamaterials, biological

The manufacturing of large scale structures with Additive Manufacturing (AM) represents one of the main challenges facing the construction industry today. The first recent large-scale realizations with the Wire-And-Arc Additive Manufacturing (WAAM) technology have shown the potential of WAAM in changing the way steel structures are currently designed and manufactured. However, despite these pioneering

Residual stresses and deflections are two major issues in laser-based powder bed fusion (L-PBF) parts. One of the most efficient and reliable ways for predicting residual stresses and final distortions is via a calibrated numerical model. In this work, a part-scale finite element thermo-mechanical model for Ti6Al4V is developed in the commercial software Abaqus/CAE 2018. The flash heating (FH) method

Metal additive manufacturing (AM) techniques are promising to build complex components in automotive, aerospace and biomedical industries. However, as built AM parts generally present residual stresses which may degrade the fatigue resistance of the material. Although the AM techniques have been substantially studied, few data about the residual stress level and distribution are available in literature

The M789 steel was designed by voestalpine group based on Grade 250 maraging steel to maintain good printability and increase the corrosion resistance. In this work, the M789 steel was manufactured by laser powder bed fusion process. The microstructural evolution of additively manufactured M789 steel was studied using optical and electron microscopy techniques. In the as-printed condition, the epitaxial

Laser beam Powder Bed Fusion (PBF-LB) is an increasingly attractive technology due to its capability of manufacturing complex and customised metal parts. However, the build cycle time and resulting residual stress profiles are limiting a wider uptake of PBF-LB manufacturing. The incorporation of additional laser beams in a single build chamber, i.e. multi-laser beam Powder Bed Fusion (PBF-MLB) technology

Selective Laser Melting (SLM) or Laser Powder Bed Fusion (L-PBF) is the most studied laser-based additive manufacturing process for metals and alloys. One important issue in SLM is the time-consuming identification of a process window leading to quasi fully dense parts (> 99.8%), usually based on trials and errors. As some metal powders may be very expensive, and therefore not suitable for a whole

Limited methods exist to integrate patterning of free-spanning hydrogel microfibres as part of an additive manufacturing strategy. We demonstrate 3D additive batch electrospinning (3D-abES) workflow to efficiently produce layered hydrogel gelatin microfibres, tethered to 3D printed thermoplastic structures of various shapes. Enabled by the digital-design approach, multiple 3D printed fibre devices

Laser sintering (LS) is widely used to produce functional polymeric parts; however, the resulting parts are often limited by their porous structure, and performance of the part may be strongly anisotropic. Relating the structural features of parts to build process conditions or powder feedstock has been explored previously. In contrast, little is known regarding how the unique internal structures of

Laser Powder-Bed Fusion (L-PBF), often called selective laser melting (SLM), is a powder-bed fusion process in Additive Manufacturing (AM) that uses a laser beam to selectively fuse layers of powder into near net-shape components with little porosity. However, inconsistencies in the part properties due to the presence of defects in as-built components have hindered the widespread adoption of L-PBF

The present work aims at quantifying and enhancing the flowability of cohesive metal powders, in particular aluminium powders, for their use in Additive Manufacturing processes such as Laser Metal Deposition. A flowability criterion, the population-dependent granular Bond number, is calculated for various metal powder samples, which are then tested with a funnel flowmeter under vibrational assistance

When selecting a material for dies and molds, strength is needed at high temperatures to hold the shape of the component along with a high thermal conductivity to decrease the solidification time of the components. This need has led to the investigation of Cu to H13 tool steel bi-metallic structures. Utilizing a directed energy deposition experimental setup, two fabrication approaches were used: direct

The persistent shortage of donor-organs for transplantation and accurate tissue models for disease study has resulted in a high demand for artificial tissues and organs. The field of biofabrication steers efforts into building 3D-tissue scaffolds by applying a combination of cells, biomaterials and engineering methods. Although researchers have successfully fabricated various tissue-like constructs

This work presents Computational Fluid Dynamics (CFD) simulations of the polymer flow inside the hot-end during material extrusion additive manufacturing. Two CFD models are investigated: a previously-published one-phase model, where the entire domain is filled with liquid, and a novel model, where the free surface of the polymer inside the channel is resolved. Both models predict a recirculation region

It is widely accepted that gas porosity and lack-of-fusion flaws can degrade both static and dynamic mechanical performance of additively manufactured components, limiting the use of AM components in critical applications. However, the mechanisms by which these flaws form are still debated, and their impact on dynamic material performance have yet to be fully quantified. This work outlines the current

This paper describes an innovative 3D-printed beam-based lightweight structure that is used to increase the adhesion strength of metal-composite joints without damaging the composite fibers. It is conceived as the interface between the two parts to be joined: by filling the voids of this structure with resin, a mechanical interlocking effect can be generated to enhance the mechanical properties of

Although multiple-material additive manufacturing has progressed rapidly over the last few years, little progress has been made so far on the additive manufacturing of metal/polymer hybrid components due to significantly different material properties. In this study, we investigated the printing of hybrid metal (Cu10Sn) and polymer (PA11) objects through a proprietary multiple-material laser powder

The microstructures and tensile properties of additively manufactured Ti-base alloys were investigated. Ti-6Al-4V and Co-Cr-Mo alloy powders were blended and used for directed energy deposition of bulk samples containing 5 and 10 wt.% Co. The Ti-6Al-4V and 5 wt.% Co samples exhibited an α phase at β grain boundaries, which caused a significant reduction and anisotropy of the tensile ductility. A single-phase

This study investigates the effects of build orientation and laser-energy density on the pore structure, microstructure, and tensile properties of Inconel 718 manufactured by laser powder bed fusion. Three different build conditions were selected for comparison based on previous research (namely, the conditions that resulted in the worst and best fatigue lifetimes): 0° build orientation and 38 J/mm3

Selective laser sintering (SLS) offers the possibility of manufacturing complex parts without tools and thus enables the cost-effective production of individualized products. In contrast to this advantage, the producible component dimension is restricted due to the dimensions of the building chamber of commercial SLS systems. Furthermore, a great amount of cost-intensive powder is necessary for the

In-situ vision data acquisition, feature extraction, and analysis are ongoing challenges for quality assessment in directed energy deposition (DED). This work proposes a method for detecting target regions in the laser-material interaction zone based on a low-cost high-dynamic-range (HDR) vision sensor. Adaptive image thresholding, connected component analysis, and iterative energy minimization are

Due to the nature of the Electron Beam Powder Bed Fusion (EB-PBF) process, it offers an opportunity to produce parts with desired localized mechanical properties by influencing the microstructure evolution of built components through process parameters adjustment. This research demonstrated this potential, not only producing IN718 components with custom grain structures but also successfully produced

Increasing industry acceptance of powder bed metal Additive Manufacturing requires improved real-time detection and classification of anomalies. Many of these anomalies, such as recoater blade impacts, binder deposition issues, spatter generation, and some porosities, are surface-visible at each layer of the building process. In this work, the authors present a novel Convolutional Neural Network architecture

Two-photon lithography (TPL) is an additive manufacturing technique for fabricating three-dimensional objects with nanoscale features. A main challenge of TPL is the routine and labor-intensive task of finding suitable light dosage parameters, i.e. writing speed and laser intensity that induce photo-polymerization within a wide variety of candidate photo-curing polymers. Another challenge is the monitoring

Additive manufacturing (AM) of ceramics, particularly of zirconia, is becoming of increasing interest due to the substantial freedom available in the design and fabrication process. However, due to the novelty of the field and the challenges associated with printing dense bulk ceramics suitable for structural applications, thorough investigations that explore the effects of printing on the mechanical

The ability to precisely manipulate and control extruded materials is essential in the additive manufacturing industry. In addition to the gravity force acting on the extruded medium, here we demonstrate that the employment of a Coulomb force which results from a strategically applied electric field holds a great promise to enhance three-dimensional (3D) printing systems and derive new products. In

In-situ layerwise imaging in laser powder bed fusion (L-PBF) has been implemented by many system developers to monitor the powder bed homogeneity. Increasing attention has been recently devoted to the possibility of using the same sensing approach to detect also in-plane and out-of-plane geometrical distortions of the part while it is being produced. To this aim, seminal works investigated the suitability

Spatter causes defect formation, powder redistribution and contamination in laser powder bed fusion (LPBF) additive manufacturing process. It is critical to distinguish different types of spatter and understand their features and formation mechanisms. This work reveals the features and formation mechanisms of five unique types of spatter during the LPBF process by in-situ high-speed, high-energy x-ray

The effects of surface roughness on the high-temperature corrosion of nickel-based superalloy X produced through electron-beam melting (EBM) additive manufacturing were studied. Surface area of samples in the rough, as-fabricated condition was measured using a 2D cross-section image analysis technique and a 3D image analysis technique. To verify the accuracy of surface area measurements, oxidation

Inspired by the multiscale configuration of the microstructure of cork, the paper describes the design, 3D printing, and evaluation of a new type of multilayered cellular composite (MCC) structure composed of hard brittle and soft flexible phases. The mechanical behavior of 3D printed MCC structures have been investigated both experimentally and numerically. The experiments show that the MCC structure

Two-scale concurrent design of lattice material microstructures and their macroscale distributions can effectively enlarge the design space, and thus achieve lightweight structures with desirable mechanical and multi-physics performances. Most of the existing inverse homogenization-based design methods do not take into consideration the connectivity issues of the microstructures. In practice, this

Fatigue performance of Inconel 718 (IN718) parts built using laser powder bed fusion (L-PBF) is often poorer than that of the cast and wrought alloy parts. This is because of detrimental effects arising from the microstructures such as brittle phases and anisotropy as well as porosities. To improve fatigue performance of L-PBF IN718, two types of post processes namely hot isostatic pressing (HIP) (performed

In additive manufacturing (AM), the microstructure evolution is rather complex and plays a critical role in the mechanical performance. To predict the microstructure, many numerical models have been proposed, but solid-state phase transformations are usually not incorporated. In this work, we develop a Cellular Automaton (CA) model to simulate the solid-state phase transformation with alloy element

This article examines the process of redesigning a conventionally manufactured hydraulic manifold to one designed for additive manufacturing (DfAM). In this case, the factors to be optimized included minimizing the support material, and post-processing required to make the part, as well as minimizing the products’ weight and print time. Improvement in product functionality would also be a desirable

The additive manufacturing (AM) of the γ` precipitation strengthened Ni-base superalloys still remains a challenge due to their susceptibility to micro-cracking. Post-processing, such as HIPing, has been shown to heal the micro-cracks but it remains desirable to prevent the micro-cracking from even occurring. Numerous studies highlighting potential mechanisms for micro-cracking exist but few solutions

A range of Al/diamond metal matrix composites using advanced core-shell structured diamond powders was fabricated employing solid-state cold spray additive manufacturing technology. Cold spray technique combined with core-shell structured diamond particles has demonstrated excellent capability to produce dense Al/diamond composites with superior tribological properties. The core-shell structured diamond