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In-situ Measurements and Thermo-mechanical Simulation of Ti-6Al-4V Laser Solid Forming Processes
摘要： Residual stresses and distortions are two technical obstacles for popularizing the Additive Manufacturing (AM) technology. The evolution of the stresses in AM components during the thermal cycles of the metal depositing process is not yet clear, and more accurate in-situ measurements are necessary to calibrate and validate the numerical tools developed for its simulation. In this work a fully coupled thermo-mechanical analysis to simulate the Laser Solid Forming (LSF) process is carried out. At the same time, an exhaustive experimental campaign is launched to measure the temperature evolution at different locations, as well as the distortions and both the stress and strain fields. The thermal and mechanical responses of single-wall coupons under different process parameters are recorded and compared with the numerical models. Good agreement between the numerical results and the experimental measurements is obtained. Sensitivity analysis demonstrates that the AM process is significantly affected by the laser power and the feeding rate, while poorly influenced by the scanning speed.
关键词： Numerical simulation,Laser Solid Forming (LSF),Thermo-mechanical analysis,Additive manufacturing (AM),In-situ measurements of residual stresses
更新于2025-11-28 14:24:20
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Interaction between powder particle and gas-liquid interface of the melt pool during laser solid forming process
摘要： The three-dimensional (3-D) simulation of powder particle entering melt pool during laser solid forming (LSF) was carried out in our quest to establish a general representative model of this phenomenon. The effect of the gas-liquid interface on the motion state of the powder was analyzed, and the accuracy and universality of the model were verified using a high-speed photographic experimental approach. Further, the simulation process of the Ti-6Al-4V powder particle entering the high-temperature Ti-6Al-4V melt pool was carried out. The effects of the gas-liquid interface of the melt pool on the motion state of the powder particle and the disturbing of the powder particle on the melt pool were studied. It was found that the running speed of the particle experienced a rapid decrease and then a slower decrease in the process of entering the pool. Also, the particle serves as a transport medium of gases and carries the gases into the pool, which could form pores in the deposited layer. When the particles enter the melt pool at varied speeds, the ratio of the instantaneous speed of the particle entering the pool to the initial incident speed differs, which increases with increasing initial speed.
关键词： Melt pool,Laser solid forming,Powder particle,Gas-liquid interface,Interaction
更新于2025-09-23 15:19:57
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A Real-Time Method to Detect the Deformation Behavior during Laser Solid Forming of Thin-Wall Structure
摘要： Laser solid forming (LSF) is a promising additive manufacturing technology. In the LSF process, deformation behaviors dictate the accuracy of the produced parts. In this study, by using a laser displacement detector based on laser triangulation principle, an accurate and effective real-time detection method was established to monitor the real-time deformation behavior of the key position during the LSF of a thin-wall structure. The results confirmed that increasing thin-wall length results in increasing final deformation of the edge. The displacement fluctuation range and value in the middle of thin wall are both smaller than that of the positions near the end, while the entire displacement changing direction in the middle is opposite to that of the end positions. When the deposition process is paused, the deformation of the thin wall during the cooling stage will deviate the position of the deposited thin wall, resulting in the dislocation between the subsequent deposited part and that before the pause, which affect the dimensional accuracy of the thin wall structure. This non-contact real-time detection method also confirmed the ability to monitor the initiation of cracking during the LSF process, and a potential to be used for the on-line feedback control of deformation of detected key position of deposited structure.
关键词： laser solid forming,real-time detection,accuracy,crack,additive manufacturing,deformation behaviors
更新于2025-09-23 15:19:57
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Solidification Effect on the Microstructure and Mechanism of Laser Solid Forming Produced Flame-Resistant Ti-35V-15Cr Alloy
摘要： The block and thin-wall Ti-35V-15Cr samples were built by laser solid forming (LSF). The extremely sensitive thermal behavior condition in LSF results in significantly different microstructure. The microstructure of LSF-produced block sample mainly consists of epitaxial columnar dendritic grains, while that of the thin-wall sample is mainly composed of near-equiaxed grains together with sub-grains formed in the near-equiaxed grains.
关键词： sub-grains,Laser solid forming,temperature gradient,Ti-35V-15Cr,thermal cycling
更新于2025-09-23 15:19:57
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Formation Mechanism of Dilute Region and Microstructure Evolution in Laser Solid Forming TA15/Ti2AlNb Dual Alloy
摘要： TA15/Ti2AlNb multiple-layer samples and a dual-alloy sample were fabricated by laser solid forming (LSF) in this study. The formation mechanism of the dilute region and microstructure evolution of the dual alloy were analyzed. The results con?rmed a “step” distribution of the composition among several initial layers in the multiple-layer samples, which can be explained by calculating the ratio of the remelted zone to the deposited Ti2AlNb zone in each deposited layer. However, the “step” compositional distribution disappears, and the compositional variation tends to be more continuous and smooth in the TA15/Ti2AlNb dual-alloy sample, which is attributed to alloy elements’ di?usion at the subsequent multiple re-melting and the longer thermal cycle. The macrostructure of the TA15/Ti2AlNb dual-alloy sample consists of epitaxially grown columnar prior β grains at the TA15 side and equiaxed grains at the Ti2AlNb side, while the microstructure shows a transition of α+β→α+α2 +B2+O with increasing amounts of Ti2AlNb, leading to the microhardness also changing signi?cantly.
关键词： dilute region,microstructure evolution,laser solid forming,TA15/Ti2AlNb dual alloy
更新于2025-09-19 17:13:59
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Path Generation Method for Aero- Engine Free-Form Surface Blade in Laser Solid Forming
摘要： Blade is the critical and extensively used component of aero-engine, which machining quality directly affects engine performance. Due to its ?exibility, laser solid forming (LSF) from powders is widely used to synthesis novel materials, build three-dimensional parts, repair damage part and form surface coating in advanced manufacturing. To repair damaged parts or form surface coating, especially for aero-engine free-form surface blade, process of numerical control or robotic LSF is applied in industry. Nevertheless, on account of the complex geometry of the free-form surface, it’s quite a challenge to generate proper laser beam paths according to the process requirements of LSF. To address this problem, a path generation method based on the differential geometry is presented. The generated paths can ensure the overlap requirements between deposited tracks as well as paths shifts between adjacent layers. The proposed method has been applied to two examples to verify their validity, and there exists a great potential for the applications in aero-engine manufacturing industry, especially in the LSF repair or surface coating of free-form surface blade.
关键词： coating,laser solid forming,Blade repair,free-form surface,path generation
更新于2025-09-11 14:15:04
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In situ tailoring microstructure in laser solid formed titanium alloy for superior fatigue crack growth resistance
摘要： For damage tolerance (DT) titanium alloy, the fatigue crack growth resistance (FCGR) is a critical properties requirement for engineering applications. However, the Ti-6Al-4V-DT parts fabricated by laser solid forming (LSF) suffer from low FCGR, because of predominant basket-wave microstructure. Here, we have explored a novel LSF fabrication design to produce full colony microstructure, via in-situ controlled growth. The creation of such microstructures leads to superior FCGR, which markedly exceed conventional additive manufactured and mill-annealed samples. The present works provide a significant guidance for LSF-fabricated titanium alloy with high DT properties.
关键词： Titanium alloy,Fatigue crack growth resistance,Laser solid forming,Colony microstructure
更新于2025-09-11 14:15:04
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The δ Phase Precipitation of an Inconel 718 Superalloy Fabricated by Electromagnetic Stirring Assisted Laser Solid Forming
摘要： Fabricating an Inconel 718 superalloy using electromagnetic stirring assisted laser solid forming (EMS-LSF) is a novel method to modify its microstructure and mechanical properties by consuming the Nb element in the γ phase to alleviate interdendritic segregation. The precipitate C after EMS-LSF can help to achieve the uniform di?usion of Nb, and can also improve its mechanical properties. The precipitation behavior of the δ phase in an EMS-LSF Inconel 718 superalloy with di?erent heat treatment processes has been investigated. The results show that the morphology of the δ phase changes from rod-like to a long-needle shape and tends to grow from the inter dendrite to the core dendrite with electromagnetic ?eld intensity increasing, which is accompanied by the “cutting” and “dissolution” of the Laves phase. Through precipitation kinetics analysis, the precipitation rate of the δ phase is seen to increase with the electromagnetic ?eld intensity increasing. Under a combination of electromagnetic stirring and laser solid forming, the microhardness of the Inconel 718 samples increased slightly due to the fact that a higher content of Nb was distributed in the core dendrite resulting from the serious convection of liquid metal, which can strengthen the matrix.
关键词： electromagnetic stirring,laser solid forming,laves phase,δ phase,precipitation behavior
更新于2025-09-11 14:15:04