PEOPLE@HES-SO Directory and Skills inventory

Lecture Notes in Mechanical Engineering, 2024

Sallem Haifa, Ghorbel Hatem

Summary:

For cyclic loading applications and critical structural, the emergence of flaws in additively manufactured components is a key concern. This study highlighted the defects generated by selective laser melting (SLM) to the 17-4 PH stainless steel parts. The defects were quantified using an experimental study: Optical microscope and roughness meter to evaluate surface morphology (roughness and porosity) and microstructure. Tensile tests to evaluate the mechanical performance. The defects recorded take several forms, the most important of which are the rough and heterogeneous surface, prominent bumps on the outer surface in the shape of a hemisphere, cavities inside the spaced and adjacent parts of different shapes, internal cracks perpendicular to the printing direction, undissolved particles confined in the dissolving structure layers, brittle behaviour, non-resistant attractive and heterogeneous structure etc.

In-Situ Monitoring of Selective Laser Melted Ti–6Al–4V Parts Using Eddy Current Testing and Machine Learning

Scientific paper

Lecture Notes in Mechanical Engineering book series (LNME), 2024

Summary:

Metal laser powder bed fusion (L-BPF) technology is one of the most common and evolved additive manufacturing technologies to fabricate metal components. However, the control of defects generated during the SLM process remains an essential technological challenge for its implementation in production lines. In this work, based on the combination of eddy current testing (ECT) and machine learning (ML) approach, we propose a methodology allowing the in-situ monitoring of LPBF process porosity defects of Ti-6AL-4V components. The present empirical approach is achieved by setting up trained AI algorithms for the in-situ detection of porosity defects generated during the part fabrication. The algorithms are fed with data collected layer by layer using a specific experimental set up composed of an ECT system mounted on the machine recoater of the SLM machine. Comparison between predicted and experimental outcomes shows the effectiveness of the proposed framework which allows the prediction of porosity defects layer by layer with a mean absolute error (MAE) of 0.1% for CNN2D algorithm and 0.11% for LSTM one. The framework developed in this study can be effectively applied to quality control in additive manufacturing.

Investigation on Distortion Behaviour of Aileron Bracket Additively Manufactured Using Laser Powder Bed Fusion with Generative Design and Optimized Multi-Scaled Simulation Method

Scientific paper

EID:2-s2.0-85136971377, 2024

2023

Selective laser melting of stainless-steel :

Scientific paper ArODES

a review of process, microstructure, mechanical properties and post-processing treatments

Thabet A. M. Sghaier, Habib Sahlaoui, Tarek Mabrouki, Haifa Sallem, Joël Rech

International Journal of Material Forming, 16, 4

Summary:

Additive Manufacturing (AM) using Selective Laser Melting (SLM) has gained significant prominence across various industries involved in stainless steel part manufacturing. Selective Laser Melting makes it possible to manufacture parts with very complex geometry and with remarkable mechanical and physicochemical properties by controlling the microstructure via the appropriate choice of process parameters. This study presents a comprehensive literature review aiming to provide the scientific and technical communities with an overview of existing knowledge and experimental data regarding the effects of Selective Laser Melting parameters and conditions on the microstructure and mechanical properties of stainless-steel parts. The objective is to highlight the impact of various factors, such as process parameters, building atmosphere, post-heat treatments and initial powder characteristics on phase transformation, porosity and microcracks formation, microstructure evolution and mechanical properties of SLMed stainless steels. Additionally, the integration of emerging Smart Additive Manufacturing (SAM) requires experimental databases, properties prediction and processing parameters optimization to enhance the entire process spanning from design to final product.

Advances in additive manufacturing :

Book ArODES

materials, processes and applications : selected contributions to the 2nd advances in additive manufacturing conference (AIAM'2023), 18-20 may 2023, Hammamet, Tunisia

Tarek Mabrouki, Habib Sahlaoui, Haifa Sallem, Farhat Ghanem, Nourredine Benyahya

2023, Cham : Springer, xi, 246 p.

Summary:

This book reports on research and developments in the field of 3D printing, with a special emphasis on methods to analyse the products of additive manufacturing, and optimize different steps of the manufacturing process. Gathering selected contributions to the 2nd Advances in Additive Manufacturing Conference (AIAM' 2023), held on Mai 18-20, 2023, in Hammamet, Tunisia, this book covers a variety of topics, including: analysis of microstructure and material behavior, numerical simulation and model techniques for optimization of manufacturing processes, machine learning for quality control and automated monitoring, among others. Offering a good balance of fundamental research and industrially relevant findings, this book provides researchers and professionals with a timely snapshot of and extensive information on current developments in the field and a source of inspiration for future research and collaboration.

Mechanical Properties of Additively Manufactured 17-4PH SS: Heat Treatment

Scientific paper

Lecture Notes in Mechanical Engineering, 2023

Summary:

he effects of the thermal post-treatments on the mechanical properties of SLMed 17-4PH stainless steel are studied. Three thermal post-treatments are carried out: (E0) as received state, (E1 and E2) solution annealing treatment and (E3) aging treatment. Microhardness, impact-strength, and wear tests are carried out to determine the effect of treatment on the mechanical properties of SLMed 17-4PH. The results showed that the hardness of 17-4PH at the E0 state is a greater than the hardness of the powder. This hardness decreases slightly from 418 HV to 384 HV after the solution annealing treatment E2 and increase again after E3 ageing treatment to around 447HV. A hardness difference between the two manufacturing directions was also observed. This difference almost disappears after the E3 ageing treatment. The impact strength results show a huge drop in impact strength for 17-4PH obtained by SLM. An improvement in wear behaviour following heat treatment, especially in the case of ageing.

Nitinol Stents Printed by Selective Laser Melting

Scientific paper

Lecture Notes in Mechanical Engineering book series (LNME), 2023

Summary:

Nitinol alloys stents have been printed by Selective Laser Melting from a gas atomized powder with a composition of 50.8 at% Ni. The energy density has been adapted to set the austenite finish temperature just below the human body temperature, therefore the stent diameter can be reduced by plastic strain at lower temperature and recover its former expanded shape after being inserted in the artery. Several mesh geometries have been mechanically analyzed by finite elements modeling to ensure that the local strain will not exceed superelastic reversible capacity of 4% while squeezing the stent diameter by a factor of 4. The stent surface has been treated by electropolishing to reduce its roughness to Ra < 0.02 mm. After polishing, some samples have been coated by a 50 nm thick TiO2 layer by Atomic Layer Deposition. Biocompatibility and hemocompatibility analysis demonstrated that the TiO2 coating significantly improved hemocompatibility. Nevertheless, uncoated stents are also biocompatible and hemocompatible according to ISO-10993–12 guidelines

Advances in Additive Manufacturing: Materials, Processes and Applications

Book

2023, Suisse : Springer Nature, 246 p.

Summary:

Selective Laser Melting of Stainless-Steel: A Review of Process, Microstructure, Mechanical Properties and Post-Processing treatments

Scientific paper

International Journal of Material Forming, 2023

Summary:

Design and manufacture by SLM of a heat exchanger for SOFC

Scientific paper

Conception et fabrication par SLM d'un échangeur de chaleur pour piles SOFC

Joris Steve, Sallem Haifa, Aguiar E Silva Filipe, Peter Hugh Middleton

Advances In Additive Manufacturing (AIAM'2023), 2023

Summary:

The objectives of this project are to design and manufacture, using 3D printing, a highly energy-efficient multi-channel hydrogen heat exchanger that will both improve the efficiency of the energy conversion chain in the fuel cells and high-temperature electrolysis (SOFC / SOEC) developed by Celectis Sàrl, and recover the excess heat emitted by these systems. The approach consists of designing a multi-channel heat exchanger with an architectural structure, then optimising its geometry by means of a CFD analysis of the flow rates, and finally producing a prototype in refractory alloy (INCONEL ® Alloy HX) by additive manufacturing using SLM (Selective Laser Melting). This manufacturing technique gives considerable design freedom (e.g. TPMS structure) and will enable high exchanger compactness to be achieved, thermal inertia to be reduced and exchanger designs to be adapted to environmental constraints. The printed heat exchanger will be characterised in the laboratory in order to assess its performance and tightness. This study will also help to understand and determine the limitations of the SLM process and the advantages of this manufacturing technology for this type of application.

2023

Mechanical properties of additively manufactured 17-4PH SS :

Conference ArODES

heat treatment

Thabet A. M. Sghaier, Habib Sahlaoui, Tarek Mabrouki, Haifa Sallem, Joël Rech

Advances in Additive Manufacturing: Materials, Processes and Applications ; Proceedings of the 2nd Advances in Additive Manufacturing Conference (AIAM'2023), 13-20 May 2023, Hammamet, Tunisia

Summary:

The effects of the thermal post-treatments on the mechanical properties of SLMed 17-4PH stainless steel are studied. Three thermal post-treatments are carried out: (E0) as received state, (E1 and E2) solution annealing treatment and (E3) aging treatment. Microhardness, impact-strength, and wear tests are carried out to determine the effect of treatment on the mechanical properties of SLMed 17-4PH. The results showed that the hardness of 17-4PH at the E0 state is a greater than the hardness of the powder. This hardness decreases slightly from 418 HV to 384 HV after the solution annealing treatment E2 and increase again after E3 ageing treatment to around 447HV. A hardness difference between the two manufacturing directions was also observed. This difference almost disappears after the E3 ageing treatment. The impact strength results show a huge drop in impact strength for 17-4PH obtained by SLM. An improvement in wear behaviour following heat treatment, especially in the case of ageing.

Nitinol stents printed by selective laser melting

Conference ArODES

Jean Pralong, Livia Lerjen, Bruno Schnyder, Oksana Banakh, Tony Journot, Haifa Sallem, Samuel Rey-Mermet

Advances in Additive Manufacturing: Materials, Processes and Applications ; Proceedings of the 2nd Advances in Additive Manufacturing Conference (AIAM'2023), 13-20 May 2023, Hammamet, Tunisia

Summary:

Experimental study of morphological defects generated by SLM on 17-4PH stainless steel

Conference ArODES

Thabet A. M. Sghaier, Habib Sahlaoui, Haifa Sallem, Tarek Mabrouki, Joël Rech

Advances in Additive Manufacturing: Materials, Processes and Applications ; Proceedings of the 2nd Advances in Additive Manufacturing Conference (AIAM'2023), 18-20 May 2023, Hammamet, Tunisia

Summary:

In-situ monitoring of selective laser melted Ti–6Al–4V parts using eddy current testing and machine learning

Conference ArODES

Haifa Sallem, Hatem Ghorbel, Edouard Goffinet, Adeline Cinna, Jean Pralong, Jonatan Wicht, Bernard Revaz

Advances in Additive Manufacturing: Materials, Processes and Applications ; Proceedings of the 2nd Advances in Additive Manufacturing Conference (AIAM'2023), 13-20 May 2023, Hammamet, Tunisia