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Directed energy deposition of Al 5xxx alloy using Laser Engineered Net Shaping (LENS??)
摘要： Here, we present directed energy deposition (DED) of wrought-like Al 5xxx AlMg alloy by Laser Engineered Net Shaping (LENS?). A transition from an Al 5083 gas atomized powder feedstock to Al 5754 characteristics of the as-deposited material due to selective evaporation of Mg was observed. Density values obtained by X-ray micro-computed tomography (μ-CT) were compared to those obtained by the Archimedes method. The latter indicated a relative density as high as 99.26%. Possible origins of porosity are discussed. The as-deposited material was comprised of both equiaxed and columnar grains with no preferred crystallographic orientation and mean grain size of 36 μm. The Young's modulus, yield stress, ultimate tensile strength, fracture strain, Poisson's ratio, and total ultimate strain energy (toughness) were determined by uniaxial tensile tests combined with digital image correlation (DIC). Fractography complemented the mechanical testing. A pulse-echo ultrasonic non-destructive test was used to obtain more accurate values of the Young's and shear moduli and to adjust the value of the yield strength accordingly. The measured mechanical properties meet the requirements of international standards for wrought Al 5754 in its annealed condition.
关键词： Additive manufacturing (AM),Mechanical properties,Micro-computed tomography (μ-CT),Laser Engineered Net Shaping (LENS?),Directed energy deposition (DED),Aluminum alloys
更新于2025-09-23 15:21:01
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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