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Introduction
Additive manufacturing, Subtractive-additive hybrid manufacturing, Materials engineering, Powder technology, Aerospace engineering, Aircraft Manufacturing and Maintenance
Publications
Publications (18)
Strict control of powder properties, especially particle size distribution (PSD), is critical in the laser powder bed fusion (LPBF) process to ensure the quality of the fabricated parts. This work shows that reducing the powder size could improve the ductility of LPBF fabricated AlSi10Mg. The tensile elongation increased from 4.1% to 8.8% when AlSi...
Laser powder bed fusion (LPBF) is an outstanding additive manufacturing (AM) technology that can enable both complicated geometries and desired mechanical properties in high-value components. However, the process reliability and cost have been the obstacles to the extensive industrial adoptions of LPBF. This work aims to develop a powder recycling...
The shape variation of the laser beam is evidently observed in the laser powder bed fusion (LPBF) process because of changes in laser incidence angle and misalignment between the build plate and the laser focus plane. This issue is particularly relevant in large-scale LPBF systems where the laser beam needs to scan a large build area. However, most...
The particle size distribution (PSD) often changes as powders are cycled for recycled and different powder batches are used, challenging a critical aspect of quality assurance in the Laser Powder Bed Fusion (LPBF) process. It is therefore important to understand how powder PSD affects the processability of powder in the context of LPBF. In this wor...
The recently-developed Al-Mn-Sc based alloys fabricated by laser-powder bed fusion (L-PBF) have achieved a yield strength of 560 MPa and a ductility of 18%. However, these high strength Al alloys normally exhibit severely non-uniform plasticity due to the strain incompatibility of bimodal grain structure, which hinders their practical application....
Effective thermal conductivities (ETCs) of five commonly used metal powders in additive manufacturing have been measured at temperatures up to 750 °C. The ETCs of Al-Mn-Sc and Ti-6Al-4 V powders with different particle sizes are also investigated. When the temperature is lower than 300 °C, the ETC of metal powders is insensitive to the temperature...
Selective laser melting is an advanced additive manufacturing technology to use laser beams to melt metal powder and fabricate parts layer by layer. To understand the involved multi-physics, a validated mathematical model is employed in this work to assess effect of material properties such as powder melting and solidification coefficients and mush...
Discrete element method is used in this work to examine the mechanisms determining powder deposition efficiency during powder spreading in powder bed fusion additive manufacturing. The results reveal that powder flow in the powder pile is critical for the formation and break of transient jamming. The forces on the underlying part increase first wit...
Laser powder bed fusion (LPBF) is a powder-based Additive Manufacturing (AM) technology, where the quality control of powder feedstock is critical as the particle packing on the powder bed and laser-particle interaction during laser melting influence the quality of the final parts. In this work, two AlSi10Mg powder batches with satellite particles...
Powder spreading process is to use a spreader such as blade or roller to spread powder layers for subsequent fusion in powder bed fusion additive manufacturing. In this work, the effects of various spreader geometries on powder spreading are examined by discrete element method (DEM). The results show that a compact region in the powder pile exists....
The long production time required for large-scale parts fabricated by laser powder bed fusion (LPBF) tends to induce cracks, distortions, and overheating problems. In this work, to address these challenges, we explored and established a suitable strategy for producing large AlSi10Mg components. The platform temperatures to prevent cracks and distor...
Using gas flow to reduce laser plume attenuation is critical in the process control of laser powder bed fusion (LPBF) of metal powders. First, this work investigated Hastelloy X (HX) samples built at different gas flow speeds. Higher porosity with lack of fusion defects was found in the samples built at lower gas flow speeds, which indicates a sign...
Selective Laser Melting (SLM) is a rapidly developing and advanced manufacturing method for fabricating complex products. In SLM, the powder spreading process is crucial to ensure that the right amount of material can be fully melted by a certain laser energy input in order to minimise defects and achieve the desired microstructure. The packing den...
Laser Powder Deposition (LPD) is an additive layered manufacturing process that can deposit nearnet shape parts directly from metal powder. Metal Matrix Composites (MMCs) combine the merits of ductile metal matrix and hard ceramic reinforcement, providing enhanced properties including hardness and wear resistance. MMCs can be easily implemented in...