Microstructure and corrosion evolution of additively manufactured aluminium alloy AA7075 as a function of ageing

Additively manufactured high strength aluminium alloy AA7075 was prepared using selective laser melting. High strength aluminium alloys prepared by selective laser melting have not been widely studied to date. The evolution of microstructure and hardness, with the attendant corrosion, were investigated. Additively manufactured AA7075 was investigated both in the as-produced condition and as a function of artificial ageing. The microstructure of specimens prepared was studied using electron microscopy. Production of AA7075 by selective laser melting generated a unique microstructure, which was altered by solutionising and further altered by artificial ageing - resulting in microstructures distinctive to that of wrought AA7075-T6. The electrochemical response of additively manufactured AA7075 was dependent on processing history, and unique to wrought AA7075-T6, whereby dissolution rates were generally lower for additively manufactured AA7075. Furthermore, immersion exposure testing followed by microscopy, indicated different corrosion morphology for additively manufactured AA7075, whereby resultant pit size was notably smaller, in contrast to wrought AA7075-T6.Comment: 37 pages, includes 4 Tables and 11 Figure

Toward SLM Cost model estimation: stainless steels case study

Additive manufacturing is a capable process to produce three dimensional components from raw material and 3D design data. This layer-by-layer operating process has many advantages including high geometrical freedom to produce complex parts with reduced cost and applied especially in the aerospace, medical and automotive industry. One of the metal AM processes is Selective Laser Melting this technology is an effective manufacturing technique to build metallic and functional parts. The aim of this study is to perform an economic assessment of Selective Laser Melting by developing a cost estimation model to estimate the process cost along the process life cycle cost. The cost of manufacturing is the key point for decision making to compare the Selective Laser Melting technology with different manufacturing technologies. The cost estimation is profitable also for engineers at the preliminary design. Production costs are studied to find out parameters influencing the Selective Laser Melting process such as machine cost, material, and post processing and how is the process cost could be optimized. A case study on Selective Laser Melting of stainless steels is presented to illustrate the cost model. This work presents a more realistic cost model of Selective Laser Melting based on the activity approach and including all steps of manufacturing with SLM such as part design and post processing such as heat treatment. This research enables us to understand the entire value network of Selective Laser Melting. It has been found that, the machine cost was by far the largest factor in Selective Laser Melting, followed by the post processing cost

Toward SLM Cost model estimation: stainless steels case study

Additive manufacturing is a capable process to produce three dimensional components from raw material and 3D design data. This layer-by-layer operating process has many advantages including high geometrical freedom to produce complex parts with reduced cost and applied especially in the aerospace, medical and automotive industry. One of the metal AM processes is Selective Laser Melting this technology is an effective manufacturing technique to build metallic and functional parts. The aim of this study is to perform an economic assessment of Selective Laser Melting by developing a cost estimation model to estimate the process cost along the process life cycle cost. The cost of manufacturing is the key point for decision making to compare the Selective Laser Melting technology with different manufacturing technologies. The cost estimation is profitable also for engineers at the preliminary design. Production costs are studied to find out parameters influencing the Selective Laser Melting process such as machine cost, material, and post processing and how is the process cost could be optimized. A case study on Selective Laser Melting of stainless steels is presented to illustrate the cost model. This work presents a more realistic cost model of Selective Laser Melting based on the activity approach and including all steps of manufacturing with SLM such as part design and post processing such as heat treatment. This research enables us to understand the entire value network of Selective Laser Melting. It has been found that, the machine cost was by far the largest factor in Selective Laser Melting, followed by the post processing cost

Anisotropy of additively manufactured Ti-6-4 lattice structure

Selective laser melting (SLM) is an additive manufacturing technique, where several aspects resulting in the anisotropy of properties is combined. This study provides an analysis of selective laser melting of the diamond lattice structure of Ti-6Al-4 in terms of anisotropy of Vickers microhardness depending on the location and direction of indentation. A statistical review of microhardness values is presented. © 2019 Author(s)

Damping behavior of 316L lattice structures produced by Selective Laser Melting

Selective Laser Melting is a powder-bed additive manufacturing technology that allows producing fully-dense metal objects with complex shapes and high mechanical properties. In this work, Selective Laser Melting was used to produce 316L specimens including lattice structures with the aim of exploring the possibility given by additive manufacturing technologies to produce parts with increased damping capacity, especially in relation to their weight. The internal friction of bulk and lattice specimens was measured in terms of delay between stress and deformation (i.e. tanδ) for different applied loads and frequencies. A finite element model was used to design the test and microstructure investigations were performed to support the results obtained by dynamo-mechanical tests. Keywords: Additive manufacturing, Selective Laser Melting, 316L, Lattice structure, Damping, Internal frictio

Selective laser melting of aluminium alloys

Metal additive manufacturing (AM) processes, such as selective laser melting, enable powdered metals to be formed into arbitrary 3D shapes. For aluminium alloys, which are desirable in many high-value applications for their low density and good mechanical performance, selective laser melting is regarded as challenging due to the difficulties in laser melting aluminium powders. However, a number of studies in recent years have demonstrated successful aluminium processing, and have gone on to explore its potential for use in advanced, AM componentry. In addition to enabling the fabrication of highly complex structures, selective laser melting produces parts with characteristically fine microstructures that yield distinct mechanical properties. Research is rapidly progressing in this field, with promising results opening up a range of possible applications across scientific and industrial sectors. This paper reports on recent developments in this area of research as well as highlighting some key topics that require further attention

Processing Parameters for Selective Laser Melting (SLM) of Gold

Research into laser processing of different metals has enabled Solid Freeform Fabrication (SFF) processes to produce parts for a wide variety of applications. However, less focus has been made on the processing of precious metals. Currently little research has been reported on the processing of precious metals and alloys using the Selective Laser Melting (SLM) process. Here we present an initial investigation into the processing of 24 carat gold (Au) powder using a SLM system. Gold powder was tested for apparent density, tap density, particle shape and size distribution. A quality check of the specimen was carried out using a Scanning Electron Microscope (SEM) for sinterability and occurrence of porosity. Significant processing parameters were also identified.Mechanical Engineerin

Multi-Beam Strategies for the Optimization of the Selective Laser Melting Process

The additive manufacturing of metal parts is of increasing importance for various industry sectors, but processes like selective laser melting are still lacking of robustness especially in the case of hard to process materials. The local adjustment of temperature fields around the melt pool seems promising to decrease melt pool and stress related defects because the boundary conditions can be tailored to positively influence the melt pool dynamics and lifetime as well as the temperature gradients which are the main reason for distortion and cracking. Therefore a selective laser melting laboratory machine was built up which features two independent lasers and beam deflection units which are adapted to synchronization. To discuss the usability of different synchronized multi-beam strategies for further process improvement, computational and experimental evaluations are used to investigate the strategies‘ influences on the process dynamics of the selective laser melting process.Mechanical Engineerin

An investigation of the mechanical properties of metallic lattice structures fabricated using selective laser melting

Metallic lattice structures manufactured using selective laser melting are widely used in fields such as aerospace and automobile industries in order to save material and reduce energy consumption. An essential element of metallic lattice structures design is determining their mechanical behaviors under loading conditions. Theoretical method based on beam theory has been proposed for evaluating the behaviors of the commonly used body-centered cubic lattice structures. However, it is difficult to predict theoretically the properties of the uniaxially reinforced lattice structures based on the body-centered cubic structures. Since the reinforced structures have superior strength to weight ratio and are deemed promising in lightweight-design applications, this article proposed a force-method-based theoretical method to calculate the mechanical properties of the body-centered cubic structure and its two types of uniaxially reinforced structures fabricated via selective laser melting. The finite element analysis and compression experiment study of selective laser melting samples made using Ti6Al4V powders demonstrated the validity of the proposed analytical method

PECULIARITIES OF SINGLE TRACK FORMATION FROM TI6AL4V ALLOY AT DIFFERENT LASER POWER DENSITIES BY SELECTIVE LASER MELTING#

Published ArticleThis paper describes the geometrical characteristics of single tracks manufactured by selective laser melting (SLM) at different laser powers (20-170 W) and scanning speeds (0.1-2.0 m/s). Simulation of temperature distribution during processing is carried out. A conclusion about the optimal process parameters and peculiarities of selective laser melting of Ti6Al4V alloy at low and high laser powers and scanning speeds is reached. The analysis of temperature fields creates opportunities to build parts with the desired properties by using SLM