scholarly journals Thermoelectric magnetohydrodynamic control of melt pool dynamics and microstructure evolution in additive manufacturing

2020 ◽  
Vol 378 (2171) ◽  
pp. 20190249 ◽  
Author(s):  
A. Kao ◽  
T. Gan ◽  
C. Tonry ◽  
I. Krastins ◽  
K. Pericleous
Keyword(s):  
Magnetic Field ◽  
Additive Manufacturing ◽  
Microstructure Evolution ◽  
Defect Formation ◽  
Physical Phenomenon ◽  
Convective Transport ◽  
Great Promise ◽  
Practical Implementation ◽  
Field Orientation ◽  
Melt Pool

Large thermal gradients in the melt pool from rapid heating followed by rapid cooling in metal additive manufacturing generate large thermoelectric currents. Applying an external magnetic field to the process introduces fluid flow through thermoelectric magnetohydrodynamics. Convective transport of heat and mass can then modify the melt pool dynamics and alter microstructural evolution. As a novel technique, this shows great promise in controlling the process to improve quality and mitigate defect formation. However, there is very little knowledge within the scientific community on the fundamental principles of this physical phenomenon to support practical implementation. To address this multi-physics problem that couples the key phenomena of melting/solidification, electromagnetism, hydrodynamics, heat and mass transport, the lattice Boltzmann method for fluid dynamics was combined with a purpose-built code addressing solidification modelling and electromagnetics. The theoretical study presented here investigates the hydrodynamic mechanisms introduced by the magnetic field. The resulting steady-state solutions of modified melt pool shapes and thermal fields are then used to predict the microstructure evolution using a cellular automata-based grain growth model. The results clearly demonstrate that the hydrodynamic mechanisms and, therefore, microstructure characteristics are strongly dependent on magnetic field orientation. This article is part of the theme issue ‘Patterns in soft and biological matters'.

scholarly journals Laser Remelting Process Simulation and Optimization for Additive Manufacturing of Nickel-Based Super Alloys

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 177
Author(s):  
Fabian Soffel ◽  
Yunong Lin ◽  
Dominik Keller ◽  
Sergei Egorov ◽  
Konrad Wegener
Keyword(s):  
Additive Manufacturing ◽  
Defect Formation ◽  
Reference Conditions ◽  
Industrial Process ◽  
Process Conditions ◽  
Laser Remelting ◽  
Conduction Model ◽  
Simulation And Optimization ◽  
Melt Pool ◽  
Process Simulation And Optimization

Nickel-based super alloys are popular for applications in the energy and aerospace industries due to their excellent corrosion and high-temperature resistance. Direct metal deposition (DMD) of nickel alloys has reached technology readiness for several applications, especially for the repair of turbomachinery components. However, issues related to part quality and defect formation during the DMD process still persist. Laser remelting can effectively prevent and repair defects during metal additive manufacturing (AM); however, very few studies have focused on numerical modeling and experimental process parameter optimization in this context. Therefore, the aim of this study is to investigate the effect of determining the remelting process parameters via numerical simulation and experimental analyses in order to optimize an industrial process chain for part repair by DMD. A heat conduction model analyzed 360 different process conditions, and the predicted melt geometry was compared with observations from a fluid flow model and experimental single tracks for selected reference conditions. Subsequently, the remelting process was applied to a demonstrator repair case. The results show that the models can well predict the melt pool shape and that the optimized remelting process increases the bonding quality between base and DMD materials. Therefore, DMD part fabrication and repair processes can benefit from the remelting step developed here.

High Resolution Current Imaging by Direct Magnetic Field Sensing

2003 ◽  
Author(s):  
S.I. Woods ◽  
Nesco M. Lettsome ◽  
A.B. Cawthorne ◽  
L.A. Knauss ◽  
R.H. Koch
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Spatial Resolution ◽  
Great Promise ◽  
Magnetoresistive Sensor ◽  
Magnetic Sensitivity ◽  
Current Lines ◽  
Scanning Squid ◽  
Scanning Fiber ◽  
Ferromagnetic Probe

Abstract Two types of magnetic microscopes have been investigated for use in high resolution current mapping. The scanning fiber/SQUID microscope uses a SQUID sensor coupled to a nanoscale ferromagnetic probe, and the GMR microscope employs a nanoscale giant magnetoresistive sensor. Initial scans demonstrate that these microscopes can resolve current lines less than 10 µm apart with edge resolution of 1 µm. These types of microscopes are compared with the performance of a standard scanning SQUID microscope and with each other with respect to spatial resolution and magnetic sensitivity. Both microscopes show great promise for identifying current defects in die level devices.

scholarly journals Modelling of Microstructure Evolution during Laser Processing of Intermetallic Containing Ni-Al Alloys

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1051
Author(s):  
Mohammad Amin Jabbareh ◽  
Hamid Assadi
Keyword(s):  
Additive Manufacturing ◽  
Rapid Solidification ◽  
Microstructure Evolution ◽  
Phase Field ◽  
Laser Processing ◽  
Field Model ◽  
Phase Field Model ◽  
Intermetallic Phases ◽  
Al Alloy ◽  
Kinetic Effects

There is a growing interest in laser melting processes, e.g., for metal additive manufacturing. Modelling and numerical simulation can help to understand and control microstructure evolution in these processes. However, standard methods of microstructure simulation are generally not suited to model the kinetic effects associated with rapid solidification in laser processing, especially for material systems that contain intermetallic phases. In this paper, we present and employ a tailored phase-field model to demonstrate unique features of microstructure evolution in such systems. Initially, the problem of anomalous partitioning during rapid solidification of intermetallics is revisited using the tailored phase-field model, and the model predictions are assessed against the existing experimental data for the B2 phase in the Ni-Al binary system. The model is subsequently combined with a Potts model of grain growth to simulate laser processing of polycrystalline alloys containing intermetallic phases. Examples of simulations are presented for laser processing of a nickel-rich Ni-Al alloy, to demonstrate the application of the method in studying the effect of processing conditions on various microstructural features, such as distribution of intermetallic phases in the melt pool and the heat-affected zone. The computational framework used in this study is envisaged to provide additional insight into the evolution of microstructure in laser processing of industrially relevant materials, e.g., in laser welding or additive manufacturing of Ni-based superalloys.

scholarly journals Microstructure evolution during binder jet additive manufacturing of H13 tool steel

2020 ◽  
Vol 36 ◽  
pp. 101534
Author(s):  
Peeyush Nandwana ◽  
Rangasayee Kannan ◽  
Derek Siddel
Keyword(s):  
Additive Manufacturing ◽  
Tool Steel ◽  
Microstructure Evolution ◽  
H13 Tool Steel

Additive manufacturing of metals: Microstructure evolution and multistage control

2021 ◽  
Author(s):  
Zhiyuan Liu ◽  
Dandan Zhao ◽  
Pei Wang ◽  
Ming Yan ◽  
Can Yang ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Microstructure Evolution

scholarly journals Annealing Texture and Microstructure Evolution in Titanium during Grain Growth in an External Magnetic Field

2007 ◽  
Vol 48 (11) ◽  
pp. 2800-2808 ◽  
Author(s):  
Dmitri A. Molodov ◽  
Christian Bollmann ◽  
Peter J. Konijnenberg ◽  
Luis A. Barrales-Mora ◽  
Volker Mohles
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Grain Growth ◽  
Microstructure Evolution ◽  
Annealing Texture
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