scholarly journals Microstructure and Tensile Properties of AlSi10Mg Alloy Manufactured by Multi-Laser Beam Selective Laser Melting (SLM)

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1337 ◽  
Author(s):  
Zhonghua Li ◽  
Zezhou Kuai ◽  
Peikang Bai ◽  
Yunfei Nie ◽  
Guang Fu ◽  
...  
Keyword(s):  
Tensile Properties ◽  
Selective Laser Melting ◽  
High Efficiency ◽  
Grain Structure ◽  
Laser Forming ◽  
Laser Melting ◽  
Forming Process ◽  
Powder Bed ◽  
Moulding Process ◽  
Melt Pool

The multi-beam selective laser forming system is a new type of powder bed laser forming equipment that is different from single-laser selective laser melting (SLM) printers. It is a new generation for a metal powder material moulding process that has high efficiency, large size and batch manufacturing. It is a new development of a powder bed laser forming process trend. In this paper, the microstructure and tensile properties of both the multi-laser-formed AlSi10Mg isolated and overlap areas are studied to ensure that the parts can achieve perfect seamless splicing and to identify whether the parts in different regions have the same performance. It was discovered that as the number of scans increases, the depth and width of the melt pool and microscopic grain structure in the overlap zone increase. The preferential crystallite growth orientation reaches the (200) plane. A small amount of smooth surface appeared at the fracture of the overlap area of the two scans, the dimples were reduced and the structure became larger, resulting in a decrease in tensile properties.

scholarly journals Correlation of selective laser melting-melt pool events with the tensile properties of Ti-6Al-4V ELI processed by laser powder bed fusion

2018 ◽  
Vol 22 ◽  
pp. 302-306 ◽  
Author(s):  
Manisha Bisht ◽  
Nachiketa Ray ◽  
Frederik Verbist ◽  
Sam Coeck
Keyword(s):  
Tensile Properties ◽  
Selective Laser Melting ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Laser Melting ◽  
Powder Bed ◽  
Melt Pool

scholarly journals An Overview of Additive Manufacturing Technologies—A Review to Technical Synthesis in Numerical Study of Selective Laser Melting

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3895 ◽  
Author(s):  
Abbas Razavykia ◽  
Eugenio Brusa ◽  
Cristiana Delprete ◽  
Reza Yavari
Keyword(s):  
Numerical Simulation ◽  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Powder Bed Fusion ◽  
Laser Melting ◽  
Powder Bed ◽  
Part Quality ◽  
Melt Pool ◽  
Wide Range ◽  
Am Processes

Additive Manufacturing (AM) processes enable their deployment in broad applications from aerospace to art, design, and architecture. Part quality and performance are the main concerns during AM processes execution that the achievement of adequate characteristics can be guaranteed, considering a wide range of influencing factors, such as process parameters, material, environment, measurement, and operators training. Investigating the effects of not only the influential AM processes variables but also their interactions and coupled impacts are essential to process optimization which requires huge efforts to be made. Therefore, numerical simulation can be an effective tool that facilities the evaluation of the AM processes principles. Selective Laser Melting (SLM) is a widespread Powder Bed Fusion (PBF) AM process that due to its superior advantages, such as capability to print complex and highly customized components, which leads to an increasing attention paid by industries and academia. Temperature distribution and melt pool dynamics have paramount importance to be well simulated and correlated by part quality in terms of surface finish, induced residual stress and microstructure evolution during SLM. Summarizing numerical simulations of SLM in this survey is pointed out as one important research perspective as well as exploring the contribution of adopted approaches and practices. This review survey has been organized to give an overview of AM processes such as extrusion, photopolymerization, material jetting, laminated object manufacturing, and powder bed fusion. And in particular is targeted to discuss the conducted numerical simulation of SLM to illustrate a uniform picture of existing nonproprietary approaches to predict the heat transfer, melt pool behavior, microstructure and residual stresses analysis.

Finite Element Thermal Analysis of Melt Pool in Selective Laser Melting Process

2018 ◽  
Author(s):  
Zhibo Luo ◽  
Yaoyao Fiona Zhao
Keyword(s):  
Heat Source ◽  
Selective Laser Melting ◽  
Computational Cost ◽  
Melting Process ◽  
Point Heat Source ◽  
Laser Melting ◽  
Line Heat Source ◽  
Powder Bed ◽  
Melt Pool ◽  
Gaussian Point

Selective laser melting is one of the powder bed fusion processes which fabricates a part through layer-wised method. Due to the ability to build a customized and complex part, selective laser melting process has been broadly studied in academic and applied in industry. However, rapidly changed thermal cycles and extremely high-temperature gradients among the melt pool induce a periodically changed thermal stress in solidified layers and finally result in a distorted part. Therefore, the temperature distribution in the melt pool and the size and shape of the melt pool directly determine the mechanical and geometrical property of final part. As experimental trial-and-error method takes a huge amount of cost, different numerical methods have been adopted to estimate the transient temperature and thermal stress distribution in the melt pool and powder bed. The most existing research utilizes the moving Gaussian point heat source to model the profile of the melt pool, which consumes a significant amount of computational cost and cannot be used to implement the part-level simulation. This research proposes a new line heat source to replace the moving point heat source. Some efforts are applied to reduce the computational cost. Specifically, a relatively large step size is used for the line heat source to reduce the number of time steps. In addition, a mesh refinement scheme is adopted to reduce the number of cells in each time step by refining the mesh close to the heat source and coarsening the mesh far away from it. On the other hand, efforts are implemented to increase the accuracy of the simulation result. Temperature-dependent material properties are considered in this FE framework. In addition, material transition among powder, liquid, and solid are incorporated in the developed FE framework. In this study, temperature simulation of one scanning track based on self-developed FE code is applied for Stainless Steel 316L. The simulation results show that the temperature distribution and history of melt pool within line heat source are comparable to that of the moving Gaussian point heat source. While the simulation time is reduced by more than two times depending on the length of line heat input. Therefore, this FE model can be used to numerically investigate the process parameters and help to control the quality of the final part.

scholarly journals Analysis of laser–melt pool–powder bed interaction during the selective laser melting of a stainless steel

2017 ◽  
Vol 29 (2) ◽  
pp. 022303 ◽  
Author(s):  
Valérie Gunenthiram ◽  
Patrice Peyre ◽  
Matthieu Schneider ◽  
Morgan Dal ◽  
Frédéric Coste ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Selective Laser Melting ◽  
Laser Melting ◽  
Powder Bed ◽  
Melt Pool

scholarly journals Feedback Control of Melt Pool Area in Selective Laser Melting Additive Manufacturing Process

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1547
Author(s):  
Syed Zahid Hussain ◽  
Zareena Kausar ◽  
Zafar Ullah Koreshi ◽  
Shakil R. Sheikh ◽  
Hafiz Zia Ur Rehman ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Feedback Control ◽  
Selective Laser Melting ◽  
Manufacturing Process ◽  
Thermal Model ◽  
Laser Melting ◽  
Powder Bed ◽  
Melt Pool ◽  
Melt Pool Size ◽  
Pool Area

Selective laser melting (SLM), a metal powder fusion additive manufacturing process, has the potential to manufacture complex components for aerospace and biomedical implants. Large-scale adaptation of these technologies is hampered due to the presence of defects such as porosity and part distortion. Nonuniform melt pool size is a major cause of these defects. The melt pool size changes due to heat from the previous powder bed tracks. In this work, the effect of heat sourced from neighbouring tracks was modelled and feedback control was designed. The objective of control is to regulate the melt pool cross-sectional area rejecting the effect of heat from neighbouring tracks within a layer of the powder bed. The SLM process’s thermal model was developed using the energy balance of lumped melt pool volume. The disturbing heat from neighbouring tracks was modelled as the initial temperature of the melt pool. Combining the thermal model with disturbance model resulted in a nonlinear model describing melt pool evolution. The PID, a classical feedback control approach, was used to minimize the effect of intertrack disturbance on the melt pool area. The controller was tuned for the desired melt pool area in a known environment. Simulation results revealed that the proposed controller regulated the desired melt pool area during the scan of multiple tracks of a powder layer within 16 milliseconds and within a length of 0.04 mm reducing laser power by 10% approximately in five tracks. This reduced the chance of pore formation. Hence, it enhances the quality of components manufactured using the SLM process, reducing defects.

Influence of multi-spot exposure of powder bed on melt pool stability in selective laser melting

2019 ◽  
Author(s):  
Marcel Slodczyk ◽  
Alexander Ilin ◽  
Thomas Kiedrowski ◽  
Vasily Ploshikhin
Keyword(s):  
Selective Laser Melting ◽  
Laser Melting ◽  
Powder Bed ◽  
Melt Pool

On the microstructure and tensile properties of Inconel 718 alloy fabricated by selective laser melting and conventional casting

2021 ◽  
Author(s):  
Minglin He ◽  
Yong Ni ◽  
Shuai Wang
Keyword(s):  
Tensile Properties ◽  
Selective Laser Melting ◽  
Inconel 718 ◽  
Cellular Structure ◽  
Cast Alloy ◽  
Grain Structure ◽  
Laser Melting ◽  
Inconel 718 Alloy ◽  
Laves Phases ◽  
Conventional Casting

In this work, we investigated the microstructure and tensile properties of Inconel 718 alloy processed by selective laser melting (SLM) and conventional casting technique using multiscale characterization methods. Results indicated that a columnar grain structure containing cellular structure units with submicron size was the major feature in the as-printed Inconel 718 alloy. At the cellular structure boundaries, the high-density dislocation tangles, segregation of Nb/Mo atoms and nano-sized Laves phases were found. Meanwhile, we also observed dislocation pile-ups and stacking faults in the interior of the cellular structure. In contrast, in the as-cast Inconel 718 alloy, both the grains and Laves phases were much coarser. Discrete dislocations, dislocation tangles and [Formula: see text]” precipitates were locally observed in the grains. Tensile results showed the as-printed Inconel 718 alloy had a higher strength and a lower elongation in comparison with those in the as-cast alloy. Based on the experimental results, the formation mechanism of the cellular structure was discussed.

Thermal Behavior and Melt-Pool Dynamics of Cu-Cr-Zr Alloy in Powder-Bed Selective Laser Melting Process

2019 ◽  
Author(s):  
M. Shafiqur Rahman ◽  
Paul J. Schilling ◽  
Paul D. Herrington ◽  
Uttam K. Chakravarty
Keyword(s):  
Thermal Behavior ◽  
Selective Laser Melting ◽  
Melting Process ◽  
Rate Variation ◽  
Cfd Model ◽  
Laser Melting ◽  
Powder Bed ◽  
Melt Pool ◽  
Functional Components ◽  
Zr Alloy

Abstract Selective laser melting (SLM) is a growing additive manufacturing (AM) technology which is capable of rapidly fabricating functional components in the medical and aviation industries. The thermophysical properties and melt-pool dynamics involved in the powder-bed SLM process play a crucial role to determine the part quality and process optimization. In this study, a 3-D computational fluid dynamics (CFD) model with Cu-Cr-Zr (C-18150) powder-bed is developed incorporating a moving conical volumetric heat source and temperature-dependent thermal properties to conduct the Multiphysics simulations of the SLM process. The melt-pool dynamics and its thermal behavior are investigated numerically and results for temperature profile, cooling rate, variation in density, thermal conductivity, specific heat capacity, and velocity in the melt pool are obtained for different laser beam specifications. The validation of the CFD model is conducted by comparing the simulation results for temperature and the melt-front motion with the analytical results found from the classical Stefan problem of the phase-change material. Studying the process parameters, melt-pool geometry, and thermal behavior of Cu-Cr-Zr alloy can generate valuable information to establish Cu-Cr-Zr as a low-cost engineering material in the AM industry.

Melting, fusion and solidification behaviors of Ti-6Al-4V alloy in selective laser melting at different scanning speeds

2020 ◽  
Vol 26 (7) ◽  
pp. 1209-1215 ◽  
Author(s):  
Snehashis Pal ◽  
Gorazd Lojen ◽  
Nenad Gubeljak ◽  
Vanja Kokol ◽  
Igor Drstvensek
Keyword(s):  
Tensile Properties ◽  
Selective Laser Melting ◽  
Solidification Process ◽  
Fabrication Process ◽  
Laser Melting ◽  
Content Type ◽  
Melt Pool ◽  
High Thermal Gradient ◽  
Thermal Phenomena ◽  
Pool Formation

Purpose Melting, fusion and solidification are the principal mechanisms used in selective laser melting to produce a product. Several thermal phenomena occur during the fabrication process, such as powder melting, melt pool formation, mixing of materials (fusion), rapid solidification, re-melting, high thermal gradient, reheating and cooling. These phenomena result in several types of pores, defects, irregular surfaces, bending and residual stress. This paper aims to focus on the physical behaviors of Ti-6Al-4V alloy at several scanning speeds and their effect on porosity and metallurgical properties. Design/methodology/approach Seven scanning speeds between 150  and 1000 mm/s were chosen to observe the occurrence of different pores, defects and microstructural formations and their effect on hardness and tensile properties. Findings The various mentioned malformations occur due to the results of possible uncertainties during the melting-fusion-solidification process. Size, shape, number, location and content of the pores varied in different samples. The a cicular a' size changes with different scanning speeds. Eventually, both porosity and microstructure have shown influential consequences on the hardness and tensile properties in the samples manufactured with different scanning speeds. Originality/value This study showed the adverse effects of different physical behaviors that occurred during the fabrication process, leading to the formation of complex pores. The causations and plausible solutions of the pore formation are interpreted in this paper. The authors observe that a circular a' size differed with scanning speeds, and these influence the mechanical properties.

scholarly journals A novel physics-based and data-supported microstructure model for part-scale simulation of laser powder bed fusion of Ti-6Al-4V

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Jonas Nitzler ◽  
Christoph Meier ◽  
Kei W. Müller ◽  
Wolfgang A. Wall ◽  
N. E. Hodge
Keyword(s):  
Selective Laser Melting ◽  
Microstructure Evolution ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Laser Melting ◽  
Cooling Rates ◽  
Powder Bed ◽  
Proposed Model ◽  
Microstructure Model ◽  
Transformation Diagrams

AbstractThe elasto-plastic material behavior, material strength and failure modes of metals fabricated by additive manufacturing technologies are significantly determined by the underlying process-specific microstructure evolution. In this work a novel physics-based and data-supported phenomenological microstructure model for Ti-6Al-4V is proposed that is suitable for the part-scale simulation of laser powder bed fusion processes. The model predicts spatially homogenized phase fractions of the most relevant microstructural species, namely the stable $$\beta $$ β -phase, the stable $$\alpha _{\text {s}}$$ α s -phase as well as the metastable Martensite $$\alpha _{\text {m}}$$ α m -phase, in a physically consistent manner. In particular, the modeled microstructure evolution, in form of diffusion-based and non-diffusional transformations, is a pure consequence of energy and mobility competitions among the different species, without the need for heuristic transformation criteria as often applied in existing models. The mathematically consistent formulation of the evolution equations in rate form renders the model suitable for the practically relevant scenario of temperature- or time-dependent diffusion coefficients, arbitrary temperature profiles, and multiple coexisting phases. Due to its physically motivated foundation, the proposed model requires only a minimal number of free parameters, which are determined in an inverse identification process considering a broad experimental data basis in form of time-temperature transformation diagrams. Subsequently, the predictive ability of the model is demonstrated by means of continuous cooling transformation diagrams, showing that experimentally observed characteristics such as critical cooling rates emerge naturally from the proposed microstructure model, instead of being enforced as heuristic transformation criteria. Eventually, the proposed model is exploited to predict the microstructure evolution for a realistic selective laser melting application scenario and for the cooling/quenching process of a Ti-6Al-4V cube of practically relevant size. Numerical results confirm experimental observations that Martensite is the dominating microstructure species in regimes of high cooling rates, e.g., due to highly localized heat sources or in near-surface domains, while a proper manipulation of the temperature field, e.g., by preheating the base-plate in selective laser melting, can suppress the formation of this metastable phase.

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