- 标题
- 摘要
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- 实验方案
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In-Process Laser Re-Melting of Thin Walled Parts to Improve Surface Quality after Laser Metal Deposition
摘要： Laser metal deposition (LMD) is an additive manufacturing process highly adaptable to medium to large sized components with bulky structures as well as thin walls. Low surface quality of as-deposited LMD manufactured components with average roughness values (Ra) around 15-20μm is one of the main drawbacks that prevent the use of the part without the implementation of costly and time-consuming post-processes. In this work laser re-melting is applied right after LMD process with the use of the same equipment used for the deposition to treat AISI 316L thin walled parts. The surface quality improvement is assessed through the measurement of both areal surface roughness Sa(0.8mm) and waviness Wa(0.8mm) parameters. Moreover, roughness power spectrum is used to point out the presence of principal periodical components both in the as-deposited and in the re-melted surfaces. Then, the transfer function is calculated to better understand the effects of laser re-melting on the topography evolution, measuring the changes of individual components contributing to the surface roughness such as the layering technique and the presence of sintered particles. Experiments showed that while low energy density inputs are not capable to properly modify the additive surface topography, excessive energy inputs impose a strong periodical component with wavelength equal to the laser scan spacing and directionality determined by the used strategy. When a proper amount of energy density input is used, laser re-melting is capable to generate smooth isotropic topographies without visible periodical surface structures.
关键词： laser metal deposition,direct energy deposition,Additive manufacturing,post-processing,surface roughness,laser re-melting
更新于2025-09-16 10:30:52
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The influence of laser engineered net shaping (LENSa?￠) technological parameters on the laser deposition efficiency and properties of H13 (AISI) steel
摘要： A successful attempt at laser cladding of H13 (AISI) hot work tool steel by the laser engineered net shaping technique is presented. Technological parameters, such as laser spot diameter, powder flow rate, and deposition velocity, were changed during the experiment. The influences of the different technological parameters on the efficiency of the cladding, geometry of the clads and properties of the deposited material were investigated. As a result, 75 different samples were deposited. The efficiency of the cladding varies significantly within the chosen range of parameters and is as low as several percentage points. The chosen parameters also appear to affect the shape of the clad, size of the heat-affected zone, microstructure and hardness of the steel, which ranged from 500 to 800 HV after deposition. The proper choice of parameters led to the desired surface hardness of the deposited material, and a heat treatment of the final product may not be necessary.
关键词： Clads geometry,Direct energy deposition,Deposition efficiency,Laser cladding,Microstructure,H13 tool steel,Microhardness,LENS?
更新于2025-09-16 10:30:52
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The Effect of Laser Power on the Microstructure of the Nb-Si Based <i>In Situ</i> Composite, Fabricated by Laser Metal Deposition
摘要： The Nb-Si in-situ composite samples were fabricated by laser metal deposition additive manufacturing technology from mechanically alloyed powders in vario-planetary ball mill. A laser metal of samples was carried out at various laser powers: 500 W, 1000 W, 1400 W. The microstructure of a sample grown at a laser power of 500 W consists of a solid solution of Nb, Nb3Si, and dendritic chains of Ti. When the laser power is increased to 1000 W, the volume fraction of silicides increases, the structural heterogeneity decreases. With further increase in laser power to 1400 W, Ti dissolves in Nb, dendritic chains disappear, Nb5Si3 silicide stabilizes.
关键词： Additive manufacturing,Nb-Si based alloy,Direct energy deposition
更新于2025-09-16 10:30:52
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Microstructure by design: An approach of grain refinement and isotropy improvement in multi-layer wire-based laser metal deposition
摘要： The additive production of metallic components with high-throughput is usually associated with high process temperatures and slow cooling rates. This typically results in strongly oriented columnar grain growth along the building direction of the structure having exceedingly large grain sizes. As a result, such structures show typically low strength and anisotropic mechanical behaviour in as-deposited condition. Consequently, post-processing is commonly performed to homogenize and eventually increase the mechanical properties of the deposited structures. In this regard, precise control of the applied process energy allows a modification of the local temperature distribution and cooling conditions during the additive manufacturing process, which strongly influence the resulting solidification microstructure. The aim of the present study is the development of an approach that allows to influence the solidification conditions in wire-based laser metal deposition of an Al-Mg alloy through specific adjustments of the laser irradiation. It was found that significantly different solidification microstructures in as-deposited condition can be achieved by adjusting the laser beam irradiance within a range resulting in conduction mode welding conditions while keeping the heat input constant. The application of high laser beam irradiances, close to the transition to keyhole mode welding, results in structures with a homogeneous large-grained solidification microstructure exhibiting a degree of anisotropy of around 12% between building direction and the direction of deposition. In contrast, the use of low laser beam irradiances close to the lower limit of stable melting, results in structures with a significantly refined microstructure. Consequently, an increase of yield strength of up to 16% and microhardness of up to 13%, as compared to structures processed with high laser beam irradiance, could be obtained. Moreover, the anisotropy of the as-deposited structure was reduced to a degree lower than 2%.
关键词： Direct Energy Deposition,Aluminium Alloy,Laser Metal Deposition,Additive Manufacturing,Laser Irradiance,Grain Refinement
更新于2025-09-11 14:15:04
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Predictive Modelling of Residual Stresses for Single Bead P420 Laser Cladding onto an AISI 1018 Substrate
摘要： Research correlating the process parameters, bead geometry, and induced residual stresses is essential for addressing geometric and functional quality issues for laser cladding based surface treatment and additive manufacturing solutions. However, analysis of variance methods cannot be readily applied, as the residual stresses values vary based on their position within the clad bead or substrate. Experimental data is used to calibrate single bead finite element models, which in turn, are used to seed an artificial neural network model and an adaptive neuro fuzzy interference system (ANFIS) model. Preliminary results indicate that the ANFIS approach has potential.
关键词： Neural Network,Residual Stresses,Simulation,Metal,Direct Energy Deposition,Adaptive Neuro Fuzzy Interference System,Additive Manufacturing,Experimental
更新于2025-09-11 14:15:04