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Proceedings Papers
Thorsten Helmig, Bingxiao Peng, Claas Ehrenpreis, Thorsten Augspurger, Yona Frekers, Reinhold Kneer, Thomas Bergs
Proc. ASME. MSEC2019, Volume 2: Processes; Materials, V002T03A028, June 10–14, 2019
Paper No: MSEC2019-2782
Abstract
Abstract In metal cutting processes the use of cutting fluids shows significant effects on workpiece surface quality by reducing thermomechanical loads on cutting tool and workpiece. Many efforts are made to model these thermomechanical processes, however without considering detailed heat transfer between cutting fluid, tool and workpiece. To account for heat transfer effects, a coupling approach is developed which combines CFD (Computational Fluid Dynamics) and FEM (Finite Element Method) chip formation simulation. Prior to the simulation, experimental investigations in orthogonal cutting in dry and wet cutting conditions with two different workpiece materials (AISI 1045 and DA 718) are conducted. To measure the tool temperature in dry as well as in wet cutting conditions, a two color pyrometer is placed inside a EDM drilled cutting tool hole. Besides tool temperature, the cutting force is recorded during the experiments and later used to calculate heat source terms for the CFD simulation. After the experiments, FEM chip formation simulations are performed and provide the chip forms for the CFD mesh generation. In general, CFD simulation and experiment are in reasonable agreement, as for each workpiece setup the measured temperature data is located between the simulation results from the two different tool geometries. Furthermore, numerical and experimental results both show a decrease of tool temperature in wet cutting conditions, however revealing a more significant cooling effect in a AISI 1045 workpiece setup. The results suggest that the placement of drilling holes has a major influence on the local tool temperature distribution, as the drilling hole equals a thermal resistance and hence leads to elevated temperatures at the tool front.
Proceedings Papers
Proc. ASME. MSEC2019, Volume 2: Processes; Materials, V002T03A085, June 10–14, 2019
Paper No: MSEC2019-2958
Abstract
Abstract Resistance spot welding (RSW) is a sheet metal welding process with broad applications, known to be more suitable for low-conductive materials, such as steels, due to concentrated and steady-state heat generation and retention at the metal interface. However, for high conductive metals such as copper, conventional welding processes in resistance spot welding has not been successful. This paper provides a comparative study of resistance welding among steel, aluminum and copper through mechanistic analyses, i.e., analytical solutions calibrated by finite element analyses. It is found when lower conductivity metals, such as steels, are welded, the applied energy can be more concentrated on the interfaces, and the heat dissipation is relatively slow, so that a close to steady-state welding condition can be reached that provides a wide and robust operation window. For welding highly conductive metals having similar melting temperature as that of electrode, the process window becomes much narrower or does not always exist without additional conditioning of materials, design or the welding processes. The physics of RSW process is analyzed based on energy equilibrium, and a new concept of pulse welding process is proposed as a required operation mode for welding copper during temperature ramping up period and prior to electrode melting. A new type of welding limit diagram (WLD) is constructed that contains three welding limit curves (WLC) for nugget formation, and the transient region. The newly constructed WLD allows a clear distinction between welding low- and high-conductive metals, and provides new understanding and a theoretical guidance for widening the weldability window.
Proceedings Papers
Proc. ASME. MSEC2019, Volume 2: Processes; Materials, V002T03A088, June 10–14, 2019
Paper No: MSEC2019-3048
Abstract
Abstract Glass-to-metal seals are important in hermetic electrical feedthroughs for high-temperature and high-pressure applications. Traditionally, glass-to-metal seals are created using a high temperature furnace with controlled pressure and atmosphere. Current manufacturing techniques for glass-to-metal seals require precise fixturing (limiting unitization) and face restrictions in terms of the coefficient of thermal expansion for the glass/metal system. This paper explores the potential to use a laser to locally heat the glass as the first step toward the additive manufacturing of glass to metal seals. Studies are conducted fusing both frit and preforms under ambient conditions. The effects of process parameters on the process are quantified. The paper shows the potential of the process using Selective Laser Melting equipment, which can lead to greater flexibility for glass-to-metal seals with respect to geometry, materials, and spatially varying properties.
Proceedings Papers
Proc. ASME. MSEC2018, Volume 2: Materials; Joint MSEC-NAMRC-Manufacturing USA, V002T04A035, June 18–22, 2018
Paper No: MSEC2018-6363
Abstract
In this study, Friction stir welding (FSW) of aluminum alloy 6061-T6511 to TRIP 780 steel are analyzed under various process conditions. Two FSW tools with different sizes are used. To understand the underlying joining mechanisms and material flow behavior, nano-CT is applied for a 3D visualization of material distribution in the weld. With insufficient heat input, steel fragments are generally scattered in the weld zone in large pieces. This is observed in a combined condition of big tool, small tool offset and low rotating speed or a small tool with low rotating speed. Higher heat input improves the material flowability and generates a continuous strip of steel. The remaining steel fragments are much finer. When the volume fraction of steel involved in the stirring nugget is small, this steel strip can be in a flat shape near the bottom, which generally corresponds to a better joint quality and the joint would fracture in the base aluminum side. Otherwise, a hook structure is formed and reduces the joint strength. The joint would fail with a combined brittle behavior on the steel hook and a ductile behavior in the surrounding aluminum matrix.
Proceedings Papers
Proc. ASME. MSEC2018, Volume 2: Materials; Joint MSEC-NAMRC-Manufacturing USA, V002T04A005, June 18–22, 2018
Paper No: MSEC2018-6694
Abstract
Graphene is an ideal reinforcement material for metal matrix composites (MMC) owing to its high strength, high ductility, light weight, as well as good bonding with metal matrix. Additive manufacturing such as selective laser melting (SLM) brings the advantages of low material waste, high flexibility, and short production lead cycle. In this study, graphene nano-platelets (GNPs) reinforced Inconel 718 composites are fabricated by SLM technique and processed under various post heat treatment schemes. It is found that fabrication of GNPs reinforced MMC using SLM technique is a viable approach. The obtained composite possesses dense microstructure and enhanced tensile strength. Post heat treatments at two levels of solution temperature (980 and 1220°C) for 1 hour followed by two-step aging are carried out. The experiment results indicate that addition of GNPs into Inconel 718 matrix results in significant strength improvement. At as-built condition, the ultimate tensile strengths are 997 and 1447 MPa, respectively at 0 and 4.4vol.% GNP content. Moreover, under as-built and solution treated condition, high content of GNPs results in overall higher UTS value and the strengthening effect is most significant at as-built condition. Meanwhile, γ′ and γ″ precipitation hardening is suppressed in the GNPs reinforced composite under aged condition due to the formation of MC carbide and depletion of Nb. Incorporating GNPs in Inconel 718 effectively inhibits the grain growth during post heat treatment.
Proceedings Papers
Denzel Bridges, Ying Ma, Cary Smith, Zhili Zhang, Anming Hu, Christopher Rouleau, Zachary Gosser, Kunlun Hong, Jinquan Cheng, Yoseph Bar-Cohen
Proc. ASME. MSEC2018, Volume 2: Materials; Joint MSEC-NAMRC-Manufacturing USA, V002T04A042, June 18–22, 2018
Paper No: MSEC2018-6627
Abstract
In this study we demonstrate a new method for depositing thick reactive multilayer films (RMFs) (thickness > 14 μm) by using Ti interlayer integration and substrate preheating during fabrication. These two adjustments are designed to alleviate internal planar stresses that cause delamination between deposited layers and peeling off the substrate. Decreasing the distance between Ti interlayers helps to eliminate delamination between deposited layers. Through high speed camera measurements, the reaction propagation speed of an RMF sample with preheating is 42% slower than the same RMF that was not preheated, indicating a slower heat release rate. The preliminary experiments on brazing Ti-6Al-4V coated with BAlSi-4 brazing material revealed dendritic structure branching out from the RMF surface into the brazing material. The dendrite structures most likely form because of rapid melting and solidification of the brazing material. However, this rapid melting and solidification cycle does not appear to occur uniformly across the BAlSi-4RMF interface which is linked to its low bonding strength. When the Ti-6Al-4V substrate is heated to 150 °C prior to ignition, the strength increases to 0.47 MPa when the total RMF thickness is 84 μm and 15 MPa of pressure is applied.
Proceedings Papers
Proc. ASME. MSEC2018, Volume 2: Materials; Joint MSEC-NAMRC-Manufacturing USA, V002T04A017, June 18–22, 2018
Paper No: MSEC2018-6628
Abstract
The purpose of this paper is to characterize the kinetics and direction of self-folding of pre-strained polystyrene (PSPS) and non-pre-strained styrene (NPS), which results from local shrinkage using a resistively heated ribbon in contact with the polymer sheet. A temperature gradient across the thickness of this shape memory polymer (SMP) sheet induces folding along the line of contact with the heating ribbon. Varying the electric current changes the degree of folding and extent of local material flow. This method can be used to create practical 3D structures. Sheets of PSPS and NPS were cut to 10 × 20 mm samples and their folding angles were plotted with respect to time, as obtained from in situ videography. In addition, the use of polyimide tape (Kapton) was investigated for controlling the direction of self-folding. Results show that folding happens on the opposite side of the sample with respect to the tape, regardless of which side the heating ribbon is on, or whether gravity is opposing the folding direction. Given the tunability of fold times and extent of local material flow, heat-assisted folding is a promising approach for manufacturing complex 3D lightweight structures by origami engineering.
Proceedings Papers
Proc. ASME. MSEC2018, Volume 2: Materials; Joint MSEC-NAMRC-Manufacturing USA, V002T04A037, June 18–22, 2018
Paper No: MSEC2018-6419
Abstract
The hybrid structures of aluminum-steel have been increasingly used for body-in-white constructions in order to reduce weight and green gas emissions. Obtaining acceptable joints between steel and aluminum required a better understanding of welding metallurgy and their effects on the resultant mechanical properties as well as the microstructure of the joints. In this research, the fiber laser welding of zero-gap galvanized steel and aluminum alloy in an overlapped configuration was carried out. The influence of heat input on the weld bead dimension, microstructural and mechanical properties of the joints was studied. A detailed study was conducted on the effects of the heat input on the penetration depth, weld width and microstructure of the laser welded dissimilar joints by means of an optical microscopy. A scanning electron microscopy with energy dispersive spectroscopy was carried out to determine the atomic percent of the elements for intermetallic compounds (IMC) occurred at the interface of the aluminum and steel. Microhardness measurement and tensile shear tests were conducted to evaluate the mechanical properties of the galvanized steel to aluminum lap joints. The experimental results showed that the penetration depth and weld width increased with the increase of heat input level. However, in order to limit IMC layer thickness and hardness at the surface of the weld seam and aluminum alloy, iron to aluminum dilution should be restricted by limiting the penetration depth. At lower heat input levels, less brittle IMC formation was formed. Consequently, with limited penetration depths at low heat input levels, up to 520 N tensile shear load achieved, with failures located in the interface of the joints.
Proceedings Papers
Proc. ASME. MSEC2018, Volume 2: Materials; Joint MSEC-NAMRC-Manufacturing USA, V002T04A008, June 18–22, 2018
Paper No: MSEC2018-6350
Abstract
The purpose of this work was to develop and analyze different materials that would be able to create the partially carbonized nanofibers through electrohydrodynamic casting followed by heat treatment. Test samples were created with different precursors containing polymer solutions and different added metal salts. After performing a series of steps to create each test sample, the sample was heat-treated to generate carbon nanofiber composites. The morphology of the carbon nanofiber composites was observed using a scanning electron microscope. Hyperthermia tests on typical fiber composites were performed.
Proceedings Papers
Proc. ASME. MSEC2018, Volume 2: Materials; Joint MSEC-NAMRC-Manufacturing USA, V002T04A044, June 18–22, 2018
Paper No: MSEC2018-6683
Abstract
This paper aims at providing a state-of-the-art review of an increasingly important class of joining technologies called solid-state welding. Among many other advantages such as low heat input, solid-state processes are particularly suitable for dissimilar materials joining. In this paper, major solid-state joining technologies such as the linear and rotary friction welding, friction stir welding, ultrasonic welding, impact welding, are reviewed, as well as diffusion and roll bonding. For each technology, the joining process is first depicted, followed by the process characterization, modeling and simulation, monitoring/diagnostics/NDE, and ended with concluding remarks. A discussion section is provided after reviewing all the technologies on the common critical factors that affect the solid-state processes such as the joining mechanisms, chemical and materials compatibility, surface properties, and process conditions. Finally, the future outlook is presented.
Proceedings Papers
Proc. ASME. MSEC2018, Volume 2: Materials; Joint MSEC-NAMRC-Manufacturing USA, V002T04A039, June 18–22, 2018
Paper No: MSEC2018-6452
Abstract
Friction self-piercing riveting (F-SPR) process has been proposed to join low ductility lightweight materials, and has shown advantages over fusion welding, solid state welding and traditional mechanical joining processes in joining dissimilar as well as low ductility materials. Because of the thermo-mechanical nature of F-SPR process, the formation of the joint is determined by riveting force and softening degree of the materials. However, it is still not clear that how exactly the riveting force and generated frictional heat jointly influence the mechanical interlocking formation and inhibit cracks during F-SPR process. To address these issues, in current study, F-SPR process was applied to join 2.2 mm-thick AA6061-T6 aluminum alloy to 2.0 mm-thick AZ31B magnesium alloy. The correlation of riveting force, torque responses as well as energy input with joint quality were investigated systematically under a wide range of process parameter combinations. It was found that a relatively greater final peak force and higher energy input were favorable to produce sound joints. Based on that, a two-stage method was proposed to better control the energy input and riveting force. It was found that the joints produced by the two-stage method exhibited significantly improved lap-shear strength, i.e., 70% higher than traditional SPR joints and 30% higher than one-stage F-SPR joints. This research provides a valuable reference for further understanding the F-SPR joint formation and process optimization.
Proceedings Papers
Proc. ASME. MSEC2018, Volume 4: Processes, V004T03A021, June 18–22, 2018
Paper No: MSEC2018-6356
Abstract
Ultrasonic welding is a solid-state joining process which uses ultrasonic vibration to join materials at relatively low temperatures. Ultrasonic powder consolidation is a derivative of the ultrasonic additive process which consolidates powder material into a dense solid block without melting. During ultrasonic powder consolidation process, metal powder under a compressive load is subjected to transverse ultrasonic vibrations resulting in a fully-dense consolidated product. While ultrasonic powder consolidation is employed in a wide variety of applications, the effect of critical process parameters on the bonding process of powder particles during consolidation is not clearly understood. This study uses a coupled thermo-mechanical finite element analysis technique to investigate the effect of critical process parameters including vibrational amplitude and base temperature on the stress, strain, and particle temperature distribution during the ultrasonic powder consolidation process. The study finds that during this process, the ultrasonically vibrating tool imparts cyclic vibratory shear stress on the particles. The simulation also revealed that the particle temperature just reaches the recrystallization point. Higher vibration amplitude imparted higher frictional heat on the particles, thereby aiding the consolidation process. The simulation study also showed indications of thermal softening and restricted grain boundary sliding during the ultrasonic powder consolidation process. The outcomes of this study can be used to further the industrial applications of ultrasonic powder consolidation process as well as other ultrasonic welding based processes.
Proceedings Papers
Proc. ASME. MSEC2018, Volume 4: Processes, V004T03A008, June 18–22, 2018
Paper No: MSEC2018-6684
Abstract
Dendritic electrolytic copper powder was sintered using a newly developed friction sintering process. Green copper pellets of 14 mm height and 16 mm diameter were prepared at room temperature with 5-ton load and 60 seconds holding time. The pellets were sintered using a newly developed rapid, cost-effective, energy efficient, green friction sintering process that allows for easy and quick removal of sintered products. An aluminum plate of 14 mm thickness and 16.1 mm diameter through hole was used to hold green pellets during sintering. Frictional heat and pressure were applied on a top plate through a rotating 18 mm diameter, flat shoulder, WC tool. Sintering was performed at 12 kN axial load and 800 rpm tool rotational speed. Sintering temperatures were measured using K-type thermocouples. SEM (scanning electron microscope) images of fractured surfaces for sintered pellets show neck formation between copper particles. The neck formation is approximately uniform throughout the depth. This is in-line with hardness results along the thickness of the pellet. The process holds promise particularly for solid-state sintering of metal based powders.
Proceedings Papers
Proc. ASME. MSEC2018, Volume 4: Processes, V004T03A044, June 18–22, 2018
Paper No: MSEC2018-6647
Abstract
Carbon fiber reinforced plastic (CFRP) are advanced engineering materials which are recognized as the most sought-after composite for several industrial applications including aerospace and automotive sectors. CFRP have superior physical and mechanical properties such as lightweight, high resilience, high-durability and high strength-to-weight ratio. CFRP composites stacked up with titanium to form multi-layered material stacks to enhance its load bearing capability. Traditional methods of stacking up CFRP and titanium involves using either high strength adhesives or rivets and bolts. The laminate structures joined by these methods often tend to fail during high load-bearing applications. Conventional metal welding technologies use high heat causing high thermal stresses and microstructural damages. Ultrasonic welding is a solid-state joining process, which has the capability of welding dissimilar materials at relatively low temperatures using ultrasonic vibration. Ultrasonic additive manufacturing (UAM) process is an ideal method to weld CFRP and Titanium. During the ultrasonic welding process, two dissimilar materials under a continuous static load are subjected to transverse ultrasonic vibrations, which results in high stress and friction between the two surfaces. This research focuses on the study of ultrasonically welding CFRP and Titanium stacks using UAM process. The study involves experimentation performed on an in-house built UAM setup. Finite element analysis is performed to understand the distribution stresses and strains during the UAM process. In this study, CFRP and Titanium layers are successfully welded using UAM process without causing any melting or significant heating. The finite element analysis study revealed that during UAM process, CFRP/Titanium stacks are subject to repeated cyclic shear stress reversals resulting in a strong weld joint. The stress-strain diagram during the process showed a considerable increase in plastic strain during the UAM process. The outcomes of this study can be used to further the industrial applications of the ultrasonic additive process as well as other ultrasonic welding based processes involving dissimilar materials.
Proceedings Papers
Proc. ASME. MSEC2018, Volume 4: Processes, V004T03A045, June 18–22, 2018
Paper No: MSEC2018-6696
Abstract
Direct metal deposition (DMD) is a major additive manufacturing (AM) process, which employs high energy beams as the heat source to melt and deposit metals in layerwise fashion so that complex structural components can be directly obtained. Similar to other metal AM processes, DMD is a complicated thermo-mechanical process, characterized by fast scan rates, large thermal gradients, rapid material phase transformations, and cyclic non-uniform temperature changes. Accurate and efficient computation of the thermal field during the DMD process is essential for understanding the fundamental microstructure evolution and developing the optimization strategy. In this paper, we aim to develop an open-source and fast computation tool for analyzing the heat transfer during the DMD process, which is based on the finite volume formulation and the quiet element method and allows development of customized functionalities at the source level. A computing tool is developed in MATLAB for fast prediction of the temperature field during metal additive manufacturing, and compared against the regular finite element analysis using a commercial software. The preliminary results show that for a system of 14400 cells, deposition of a single path takes 174 s using the commercial software, and 15.8s to 81s depending on the setting of convergence criterion using the in-house code. This represents a time reduction ranged from 90.9% to 53.4%, and the overall error is around 12.1%.
Proceedings Papers
Proc. ASME. MSEC2018, Volume 4: Processes, V004T03A032, June 18–22, 2018
Paper No: MSEC2018-6504
Abstract
Liquid Assisted Laser Beam Micromachining (LA-LBMM) process is advanced machining process which can overcome the limitations of traditional laser beam machining processes. LA-LBMM process uses a layer of a liquid medium such as water above the substrate surface during the application of laser beam. During LA-LBMM process, the liquid medium is used both in static mode in which the water is still or in a dynamic mode in which the water flows over the substrate with a specific velocity. Experimental studies on LA-LBMM process have shown that the cavity machined has a better surface finish due to a reduction in the amount of re-deposition and recast material. While LA-LBMM process promises significant improvement in laser-based micromachining applications, the process mechanisms involved in LA-LBMM process is not well understood. In the past, finite element simulation studies on LA-LBMM process is studied which could only find the temperature distribution on the substrate during machining. A clear understanding of the role of water medium during the LA-LBMM process is lacking. This research involves the use of Molecular Dynamics (MD) simulation technique to investigate the complex and dynamic mechanisms involved in the LA-LBMM process both in static and dynamic mode. The results of the MD simulation are compared with those of Laser Beam Micromachining (LBMM). The study revealed that machining during LA-LBMM process showed higher removal compared with LBMM process. The LA-LBMM process in dynamic mode showed lesser material removal compared with static mode as the flowing water carrying the heat away from the machining zone. Formation of nanoscale bubbles along with shockwave propagation is observed during the simulation of LA-LBMM process. The findings of this study provide further insights to strengthen the knowledge base of LA-LBMM process.
Proceedings Papers
Proc. ASME. MSEC2018, Volume 4: Processes, V004T03A054, June 18–22, 2018
Paper No: MSEC2018-6457
Abstract
Laser surface hardening of most of the industrial components require depth of surface modification in the range of 100–150 micron. Conventional laser surface hardening uses laser as a heat source to modify a particular area of the surface without melting in an inert gas environment. However, the hardened profile in this case shows peak hardness value at a certain depth from the top surface. Also, hardening the top surface to get relatively much higher hardness near the top surface in case of thin sheets becomes difficult due to accumulation of heat below the surface of the specimen which in turn lowers the cooling rate. Hence, self-quenching becomes inadequate. In the present study, an in-house fabricated laser processing head with coaxial water nozzle has been used to flow a laminar water-jet during the laser surface hardening process to induce forced convection at the top surface. Thus, heat gets carried away by the water-jet from the top surface and by the water from the bottom surface as well. Results show that with judicious selection of process parameters, it is possible to get higher hardness (800 HV) to that of conventional laser surface hardening (500 HV) at the top surface using this process. Present process can be used for those cases where high hardness values are required near the top surface specially for thin sheets and thermally sensitive materials.
Proceedings Papers
William J. Emblom, Robin Babineaux, Charles Nix, Katie Parr, Tyler Saltzman, Ayotunde Olayinka, Scott W. Wagner, Muhammad A. Wahab
Proc. ASME. MSEC2018, Volume 4: Processes, V004T03A055, June 18–22, 2018
Paper No: MSEC2018-6515
Abstract
Friction stir back extrusion has recently been identified as a method for manufacturing stronger, more ductile seamless tubes. The long term goal of the project described here is to miniaturize the process in order to produce highly ductile microscale tubes for biomedical, microscale heat exchanger, and fuel cell manufacturing applications. The process is similar to friction stir welding and processing in that the end of a non-cutting tool rotates against a metal workpiece, heats the workpiece, and creates an ultrafine grain structure. Conventional microtube manufacturing is done by hot direct extrusion using dies with mandrels. After the workpiece passes the mandrels, the tube segments weld together from residual heat. The work described here considers macroscale tooling design prior to down scaling to the multi and microscale. The immediate objective was to develop tooling that can produce 50mm long tubes with 12.5mm outside diameters and 6.35mm inside diameters. Design considerations such as strength, fatigue, buckling, and vibration were considered. This paper documents the development of the tooling design process that was used in order to overcome the various design issues. Tooling failure and analysis is presented as part of the evolution of the tooling design. While majority of the paper discusses the tooling design process, a final design was developed and preliminary results for friction stir back extrusion tests are presented for tubes that are 25 and 50mm long.
Proceedings Papers
Proc. ASME. MSEC2018, Volume 1: Additive Manufacturing; Bio and Sustainable Manufacturing, V001T01A030, June 18–22, 2018
Paper No: MSEC2018-6664
Abstract
Powder bed metal additive manufacturing (AM) utilizes a high-energy heat source scanning at the surface of a powder layer in a pre-defined area to be melted and solidified to fabricate parts layer by layer. It is known that powder bed metal AM is primarily a thermal process and further, heat conduction is the dominant heat transfer mode in the process. Hence, understanding the powder bed thermal conductivity is crucial to process temperature predictions, because powder thermal conductivity could be substantially different from its solid counterpart. On the other hand, measuring the powder thermal conductivity is a challenging task. The objective of this study is to investigate the powder thermal conductivity using a method that combines a thermal diffusivity measurement technique and a numerical heat transfer model. In the experimental aspect, disk-shaped samples, with powder inside, made by a laser powder bed fusion (LPBF) system, are measured using a laser flash system to obtain the thermal diffusivity and the normalized temperature history during testing. In parallel, a finite element model is developed to simulate the transient heat transfer of the laser flash process. The numerical model was first validated using reference material testing. Then, the model is extended to incorporate powder enclosed in an LPBF sample with thermal properties to be determined using an inverse method to approximate the simulation results to the thermal data from the experiments. In order to include the powder particles’ contribution in the measurement, an improved model geometry, which improves the contact condition between powder particles and the sample solid shell, has been tested. A multi-point optimization inverse heat transfer method is used to calculate the powder thermal conductivity. From this study, the thermal conductivity of a nickel alloy 625 powder in powder bed conditions is estimated to be 1.01 W/m·K at 500 °C.
Proceedings Papers
Proc. ASME. MSEC2018, Volume 1: Additive Manufacturing; Bio and Sustainable Manufacturing, V001T01A043, June 18–22, 2018
Paper No: MSEC2018-6644
Abstract
Selective Laser Melting (SLM) has been a major subject of study in the field of powder bed additive manufacturing (AM) process. It is desired to know the melt pool size and the associated thermal gradient during the powder melting process. However, there are challenges associated with accurately measuring the melt pool size as a whole by experiment alone. Therefore, the combination of experimental and numerical study may help analyze the melt pool shape in a better way. In this study, a 3D powder scale model using volume of fluid (VOF) approach has been developed using ANSYS FLUENT. A temperature dependent material property is defined and then volumetric heat source is applied to melt the powder particles. The single track results obtained from the simulation are compared with the experiment and the results show that single track width predicted by the simulation is in good agreement with the experimental counterpart. The predicted track width is within 10% error.