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Additive manufacturing (AM) has various independent parameters that affect the mechanical properties and quality of the produced parts that are not linearly the function of each other. Process parameters in metal AM are very hard to control, analyse and optimise because they affect each other even though they can be independently changed. Changing process parameters in a wide range is not possible due to the formation of problems such as cracks, balling, unmelted powders, porosity and distortion. In this paper, a numerical model to predict the value of tensile strength of selective laser melting (SLM) Ti-6Al-4V parts and analyse the effect of process parameters on the results has been proposed. Taguchi L25 Design of Experiment (DOE) across 125 samples to create a comprehensive and general overview of influential parameters on the build process was investigated. Specifically, parameters included laser power, scan speed, hatch spacing, laser pattern angle and heat treatment (HT). To evaluate and analyse the build process according to established statistical variances, a minimum of five samples based on ASTM standard (for tensile test) were prepared. Heat treatment was added to the DOE to analyse the combined process and post-process effects. Results were compared (cross-validated) against existing values found in the literature and were found to effectively predict and explain the behaviour of tensile strength when changing process parameters. [ABSTRACT FROM AUTHOR]

In recent years, additive manufacturing (AM) has been developed for industrial applications due to its superior performance, such as in building complex parts, which are especially difficult to build when using traditional methods. However, the surface quality, and dimensional and geometric accuracies of AM parts do not exceed conventionally machined parts, which hinders the AM applications. To overcome these limitations, hybrid manufacturing (HM) technology, which combines AM and subtractive manufacturing (SM) technologies in a single workstation has received a great deal of attention in academic and industrial circles to enhance material utilization, part complexity and quality control when producing functional parts. In this paper, we present research achievements using ANSI 316L stainless steel parts via the HM process and analysis of its surface morphology and microstructural characteristics, densification behaviour and mechanical properties. Specimens before and after heat treatment were analysed and compared. The study also dealt with material characterization via the Archimedes method, scanning electron microscopy (SEM), X-ray polycrystalline diffractometer (XRD) and tensile measurements. This study provides a valuable guide to determining the effectiveness of the HM process and its use when producing engineering parts. [ABSTRACT FROM AUTHOR]

Metal additive manufacturing is an emerging advanced technology, it differs from conventional manufacturing methods as machining, casting, and forging, which are either subtractive or forming. Firstly, the objective of this work is to elaborate a new 316L stainless steel material by selective laser melting (SLM) from metallic powder according to specific operating parameters, namely laser scanning speed and power. Secondly, the characterization of this developed material by 3D printing is carried out. For this purpose, metallographic observations and heat treatments at different temperatures 650, 800, and 1050 °C were performed. Thus, the contribution of this study is to develop procedure and tools to enhance their mechanical properties at the level of parts obtained by conventional processes. Therefore, samples were examined by X-RF, SEM, EDS mapping, density, and hardness measurements as well. The results show that mechanical properties of additive manufactured samples can be improved in certain conditions linked to operating parameters and heat treatment. Also, this work has allowed us to confirm the resistance of the 316L stainless steel developed by SLM to high temperatures. [ABSTRACT FROM AUTHOR]