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On the Effect of Part Orientation on Stress Distribution in AlSi10Mg Specimens Fabricated by Laser Powder Bed Fusion (L-PBF)
摘要： The freedom of design of AM products suffers from some limitations in case of powder bed metal processes, because AM part’s integrity is affected by the residual stress state that is a consequence of the thermal history during part fabrication. Aim of this work is to evaluate the effect of part orientation on stress distribution. Thus, flat samples of AlSi10Mg alloy built along different orientations are produced by means of laser powder bed fusion (L-PBF) process, also known as Selective Laser Melting (SLM). Then, the semi-destructive hole-drilling method is used to evaluate residual stresses beneath the surfaces of samples. The outcomes of the study can be exploited to define design rules in order to both minimize support structures and optimize the orientation of the part in the building volume.
关键词： Powder bed fusion,Residual stresses,Hole-drilling method,AlSi10Mg,Orientation
更新于2025-09-16 10:30:52
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A numerical investigation of similar and dissimilar clad materials on H13 steel substrate in the Laser Cladding process
摘要： Minimal dilution, controlled heat input, excellent metallurgical bonding between the clad and the substrate material made the laser cladding process more appealing compared to other conventional surface modification techniques. However, generated residual stress in the finished component encounters this process for applications. In this work, a thermo-mechanical model has been developed numerically using ANSYS’18 multi-physics platform to analyse and compare residual stresses among different cladding materials. Three different clad materials, H13 steel, Al2O3 and TiC were used on the same H13 tool steel substrate. Tensile residual stresses were observed in the clad, at interface and in substrate near the interface for all samples in X direction. It was found that Al2O3 coating on H13 steel produced lower residual stress (1220 MPa) in the clad than TiC coating on H13 steel (1359 MPa) due to lower mismatch of thermal strain. This proposed analysis offers to select the combination of clad and substrate materials having minimum residual stresses in the Laser Cladding process.
关键词： residual stresses,Laser cladding process,thermal history,materials
更新于2025-09-12 10:27:22
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Machining induced residual stresses in AlSi10Mg component produced by Laser Powder Bed Fusion (L-PBF)
摘要： The adoption of metal powder-based laser process (L-PBF) for industrial applications continues to widen, due to an increasing knowledge on additive processes and the availability of new systems for industrial production. The use of L-PBF processes requires a deeper investigation and comparison on mechanical properties of conventional and additive parts. For instance, metal parts produced by L-PBF could require additional machining operations, which alter the stress state of additive components. In this work, the effect of machining operations on the residual stress state of an AlSi10Mg component produced by L-PBF is investigated by means of the semi destructive hole-drilling method.
关键词： AlSi10Mg,Machining,Hole-drilling method,Residual stresses,Laser Powder Bed Fusion
更新于2025-09-12 10:27:22
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Residual Stress Modelling and Experimental Analyses of Ti6Al4V ELI Additive Manufactured by Laser Engineered Net Shaping
摘要： This paper focus on the experimental analyses and modelling of the residual stresses build up during laser additive manufacturing by Laser Engineered Net Shaping. Currently, additive manufactured parts employ heat treatment for the reduction of internal stresses, but then additional advantages are also possible from heat treatment. The experimental analyses focus on stress relieving heat treatment temperatures to reduce the residual stresses during laser processing of LENS Ti6Al4V ELI specimens. LENS parts out of Ti6Al4V ELI will illustrate the mechanical property possibilities resulting from the selected stress relieving heat treatments in this study. The primary aim of heat treatment in this case of Ti6Al4V ELI is the reduction of internal stresses. Due to the mechanical behaviour of Ti6Al4V as built additive manufactured parts, the heat treatment seems to be necessary to increase the mechanical behaviour, such as the fatigue performance and the breaking elongation. Optical Microscope, Scanning Electron Microscope and Vickers hardness test was employed to carry out detailed study of the resulting microstructures and Hardness. The model by COMSOL Multiphysics was employed to predict the residual stresses of as built LENS Ti6Al4V ELI and to better understand the residual stresses amounts in the Ti6Al4V ELI alloy that need to be minimized by heat stress relieving heat treatment methods. The results included the β-phase that formed in the stress relieving heat treatment process that was transformed to martensite α during the cooling process and a fine basket-weave structure emerged. The microhardness of LENS Ti6Al4V ELI alloy gradually decreased with increasing stress relieving heat treatment temperature. The computed model revealed the maximum stress of 1.78x109 MPa, the Model strongly recommended the LENS process parameters suitable to obtain Ti6Al4V ELI samples with minimal residual stresses and a further possible method to alleviate the attained residual stresses in the model to the desired elasticity.
关键词： Modelling,Additive manufacturing,Residual stresses,Heat treatment,Microstructure evolution,Laser Engineered Net Shaping (LENS)
更新于2025-09-12 10:27:22
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Application of combined laser processing in welding of heat-treated parts
摘要： The article deals with the questions of the end connections of heat-treated precision machine parts having a low stiffness, in particular, assembled Camshaft cars. To reduce the residual stresses that occur when welding heat-treated parts, it is proposed to perform preheating of heat-treated elements in the welding zone using a laser. Also, to reduce the deformations that may occur when welding axisymmetric structures with low stiffness, such as assembled Camshaft, it is proposed to use pulsed laser welding, and welding is performed only on the site previously processed by the previous laser. A laser machine based on two sources of laser radiation DLR-200-AC and YLR 150/1500-QCW-AC was used for experimental studies. The technological heads of lasers are coaxially arranged and have a single output lens, this allowed to calculate the processing program and the necessary laser power for the first and second laser source in a single technological window, as well as to synchronize the work of two laser sources. As samples were used assembled Camshafts, which consisted of a shaft with a Central hole, and heat-treated Cams. The shafts were made of steel 20 (WNr 1.0402), Cams of steel 40X (WNr 1.7034). Heat treatment of Cams was carried out by induction method. Analytical and technological features of processing are described. The cyclic combined process is described. The result is shown. Using the proposed methodology it is possible to use the technology of connecting axisymmetric parts with low stiffness both at the stage of analysis and modernization of existing designs, and at the stage of development of advanced designs.
关键词： welding,deformations,laser processing,residual stresses,Camshaft,heat-treated parts
更新于2025-09-12 10:27:22
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Effect of Laser Welding Sequences on Residual Stresses and Distortion of DP600 Steel Joints
摘要： Different materials have been welded by laser beam. This process allows to obtain high quality welds with lower thermal effect. Laser beam welding produces narrow and high penetration welds without filler material. However, this process modifies the mechanical and microstructural properties of the welded joints. Therefore, this is currently a research topic, mainly using Advanced High Strength Steel (AHSS). These materials are used in the automotive industry. As a result, it is important to study the thermometallurgical and mechanical behavior of welded steels. In addition, a tool used to approximate the thermal effect in the fusion zone (FZ) and heat affected zone (HAZ) has been the computational numerical simulation. In this work, two butt joints of DP600 steel plates of 200 mm × 150 mm and 2 mm thickness with different welding sequences were simulated using the SYSWELD finite element software. The results of both coupons were compared and it was determined that the distortion and residual stresses decreased in the second coupon by applying a different welding sequence with equal heat input.
关键词： SYSWELD,Laser welding,Finite element simulation,Residual stresses,DP600 steel,Distortion
更新于2025-09-12 10:27:22
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Improvement of the Fatigue Life of Stainless Steel Specimens by Laser Shock Processing
摘要： An investigation concerning the influence of laser shock processing (LSP) of stainless steel specimens made of 03Kh22N6M2 steel for the fatigue life by finite element modeling was performed. The known experimental fatigue life parameters were compared with the data taken from the finite element modeling. A conforming comparison is observed between the numerical and experimental data. It was shown that the thickness of the specimen is an important parameter during application of the LSP technology. It was found that with the decrease in the specimen thickness the fatigue life, conditioned by the LSP application, improves significantly. It was shown that for thin specimens (about 2 mm) the application of the LSP technology improves the fatigue life to 300%.
关键词： residual stresses,finite element modeling,fatigue life,laser-shock-wave processing
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
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Stress and Fracture of Crystalline Silicon Cells in Solar Photovoltaic Modules – A Synchrotron X-ray Microdiffraction based Investigation
摘要： Fracture of crystalline silicon (c-Si) solar cells in photovoltaic modules is a big concern to the photovoltaics (PV) industry. Cell cracks cause performance degradation and warranty issues to the manufacturers. The roots of cell fractures lie in the manufacturing and integration process of the cells and modules as they go through a series of elevated temperature and pressure processes, involving bonding of dissimilar materials, causing residual stresses. Evaluation of the exact physical mechanisms leading to these thermomechanical stresses is highly essential to quantify them and optimize the PV modules to address them. We present a novel synchrotron X-ray microdiffraction based techniques to characterize the stress and fracture in the crystalline silicon PV modules. We show the detailed stress state after soldering and lamination process, using the synchrotron X-ray microdiffraction experiments. We also calculate the maximum tolerable microcrack size in the c-Si cells to sustain the residual stress after lamination. We further demonstrate the effect of these residual stresses on the cell fractures using the widely accepted fracture (4-point bending) tests. These test results show that the soldering and lamination induced localized residual stresses indeed reduce the load-carrying capacity of the c-Si cells.
关键词： fracture,crystalline silicon,residual stresses,synchrotron X-ray microdiffraction,photovoltaic modules
更新于2025-09-11 14:15:04
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Effect of Different Forms of Application of a Laser Surface Treatment on Fatigue Crack Growth of an AA6013-T4 Aluminum Alloy
摘要： This work analyzes the effect of surface-localized laser heating treatment on the fatigue crack growth (FCG) rate on region II of the sigmoidal da/dN 3 DK curve of an aerospace-grade AA6013-T4 aluminum alloy sheet with 1.3 mm thickness. The in?uence on microstructure changes is also evaluated. Aiming to improve the FCG resistance without changing the mechanical behavior of the alloy, a Yb:?ber laser beam is defocused to generate a laser spot diameter of 2 mm, using 200 W power and a laser speed of 2 mm/s. Two laser lines are applied over fatigue C(T) specimens in two different forms: on only one and on both lateral specimen surfaces. Guinier–Preston zones, dispersoids and coarse constituent particles are found on the base material. On the heat-treated material, the same precipitates and also b￠ and Q￠ precipitates are found. These microstructural variations due to the laser thermal cycle, together with the presence of induced compressive residual stresses, improved the fatigue behavior of the material. The FCG retardation is optimized when two laser lines were applied on both lateral surfaces of the specimen.
关键词： aluminum alloy,microstructure,fatigue crack growth,residual stresses,laser surface treatment
更新于2025-09-11 14:15:04