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

Laser diode area melting for high speed additive manufacturing of metallic components

Additive manufacturing processes have been developed to a stage where they can now be routinely used to manufacture net-shape high-value components. Selective Laser Melting (SLM) comprises of either a single or multiple deflected high energy fibre laser source(s) to raster scan, melt and fuse layers of metallic powdered feedstock. However this deflected laser raster scanning methodology is high cost, energy inefficient and encounters significant limitations on output productivity due to the rate of feedstock melting. This work details the development of a new additive manufacturing process known as Diode Area Melting (DAM). This process utilises customised architectural arrays of low power laser diode emitters for high speed parallel processing of metallic feedstock. Individually addressable diode emitters are used to selectively melt feedstock from a pre-laid powder bed. The laser diodes operate at shorter laser wavelengths (808 nm) than conventional SLM fibre lasers (1064 nm) theoretically enabling more efficient energy absorption for specific materials. The melting capabilities of the DAM process were tested for low melting point eutectic BiZn2.7 elemental powders and higher temperature pre-alloyed 17-4 stainless steel powder. The process was shown to be capable of fabricating controllable geometric features with evidence of complete melting and fusion between multiple powder layers

Application of optimized laser surface re-melting process on selective laser melted 316L stainless steel inclined parts

Lower surface quality of selective laser melting (SLM) manufactured parts remains to be a key shortcoming particularly for high performance functional components. In this paper, the authors utilized Box–Behnken methodology to explore the effect of laser surface re-melting process parameters. The process parameters are:laser power, laser exposure time, laser point distance, and shell layer thickness. The experiments were conducted using Renishaw AM-250 machine. SLM manufactured parts with inclination of 45˚ up-skin were treated with a given surface roughness using laser surface re-melting (LSR). The optimization of process parameters was conducted using response surface methodology and the validation tests was carried out utilizing the determined input parameters. The results verified the effectiveness of the integrated approach and the proposed statistical model. The outcomes of this study demonstrated that selective laser melting process followed by the laser surface re-melting process is very likely to become a fast and economic integrated method for improving the inclined surface quality of SLM manufactured parts

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

An Approach to Numerical Modeling of Selective Laser Melting

AbstractTechnological parameters of selective laser melting determine the quality of the parts produced: porosity, residual stresses and so strength and plasticity. Numerical modeling can help understand this dependence. The modeling process must account for the fact that typical sizes of metal powder particles, used for selective laser melting, are comparable (near equal) to the diameter of the laser beam, so considering powder a continuum is not fully correct. It is shown that LS-DYNA finite element code has enough capability to model important features of the process – heat exchange, melting, contact interaction of the particles

Modeling of selective laser sintering/ selective laser melting

Selective laser sintering and selective laser melting are powder based additive manufacturing (AM) process that can rapidly manufacture parts with comparable mechanical properties to conventional manufacturing methods directly from digital files. However, the processing recipe development and design optimization of AM parts are often based on trial and error which erodes the benefit of AM. Modeling is a powerful tool to enable faster development cycle by significantly reducing the experimental efforts. In this paper we discussed the current status of selective laser sintering/melting modeling, in which the laser and powder interaction was studied to understand and predict the process and the properties of fabricated parts. A review of the current approach as well as future directions are presented

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

Main factors affecting the structure and properties of titanium and cobalt alloys manufactured by the 3D printing

This paper is short review the main factors affecting the structure and properties of the metals manufactured by additive technology (selective laser melting). A comparative analysis of the structure and properties of Ti6Al4V or CoCrMo alloys obtained by selective laser melting is presented. We describe the capabilities of laser melting method for producing materials with high density and high mechanical properties. The optimized process parameters for 3D printed medicine materials Ti6Al4V and CoCrMo with high density of are discussed. © Published under licence by IOP Publishing Ltd.This work was supported by Russian Found of Basic Research N “Diagnostics” AAAA-A18-118020690196-3