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A Review on Laser Powder Bed Fusion of Inconel 625 Nickel-Based Alloy
摘要： The Inconel 625 (IN625) superalloy has a high strength, excellent fatigue, and creep resistance under high-temperature and high-pressure conditions, and is one of the critical materials used for manufacturing high-temperature bearing parts of aeroengines. However, the poor workability of IN625 alloy prevents IN625 superalloy to be used in wider applications, especially in applications requiring high geometrical complexity. Laser powder bed fusion (LPBF) is a powerful additive manufacturing process which can produce metal parts with high geometrical complexity and freedom. This paper reviews the studies that have been done on LPBF of IN625 focusing on the microstructure, mechanical properties, the development of residual stresses, and the mechanism of defect formation. Mechanical properties such as microhardness, tensile properties, and fatigue properties reported by di?erent researchers are systematically summarized and analyzed. Finally, the remaining issues and suggestions on future research on LPBF of IN625 alloy parts are put forward.
关键词： additive manufacturing,heat treatment,Inconel 625,laser powder bed fusion,mechanical properties
更新于2025-09-16 10:30:52
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Determining the Effect of Different Heat Treatments on the Electrical and Morphological Characteristics of Polymer Solar Cells
摘要： The device characteristics of polymer solar cells can be improved through an annealing process. This is especially true of the carrier mobility and the light absorption of P3HT:PCBM, which improves considerably after the annealing process. In the standard structure using indium-tin-oxide (ITO) as an anode, most studies have focused on the post-annealing process, where thermal annealing is performed after device fabrication. This work reports the effects of different annealing methods for inverted polymer solar cells, using ITO as a cathode. Similar levels of light absorption and P3HT crystallinity were obtained regardless of the annealing procedure in the inverted structure. However, compared with the post-annealed device, the pre-annealed device, which was thermally annealed after deposition of the P3HT:PCBM film, exhibited better charge extraction, owing to the superior device resistances and larger MoO3 grain size. Therefore, the pre-annealing method yields better performance than the post-annealing method.
关键词： Inverted polymer solar cell,Heat treatment,Morphology,Impedance
更新于2025-09-16 10:30:52
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Local heat treatment of a laser build-up
摘要： Laser cladding or laser metal deposition involves the deposition of any weldable material onto the surface of a metal substrate by means of a laser beam. Although clad deposits are fully fusion-joined to the substrate material, the very low heat-input associated with laser cladding results in extremely low dilution as well as relatively small heat-affected zones (HAZ). Subsequent to the clad-repair process, heat treatment is normally not necessary, but some critical components may require it due to the high hardness obtained in the HAZ. Conventional heat treatments are most often time-consuming, costly and could cause possible distortion of the component. In this study local laser heat treatment of the HAZ after laser cladding has been investigated on different substrate materials (21CrMoV5-11, X22CrMoV12-1, 34CrNiMo6) as an alternative to full post-weld heat treatment (PWHT). Due to the focused heat of the laser beam, the required time at temperature for heat treatment was only a fraction compared to that of conventional heat treatments. It was observed that the HAZ hardness could indeed be lowered significantly by controlling the temperature and interaction time of the local treatment. For 21CrMoV5-11 the HAZ hardness was decreased to below 400 HV with most treatments at 800 °C, but the 8 s interaction time was found to be optimal. The X22CrMoV12-1 material showed the highest resistance to PWHT and only the longest interaction time at 800 °C resulted in HAZ hardness close to 400 HV. The largest decrease in HAZ hardness was obtained with the 34CrNiMo6 material and the longest interaction time at 700 °C resulted in the lowest hardness.
关键词： heat-affected-zone,hardness,local heat treatment,Laser,cladding
更新于2025-09-12 10:27:22
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Effects of Postweld Heat Treatment on Microstructure and Properties of Laser-Welded Ti-24Al-15Nb Alloy Joint
摘要： The microstructure evolution and mechanical properties of laser-welded joints of Ti-24Al-15Nb alloy under different postweld heat treatment (PWHT) conditions were systematically investigated. The results show that the microstructure is very sensitive to PWHT temperatures. The weld zone consists of B2 and O phases after PWHT. With the PWHT temperatures increasing from 850 to 1000 °C, the amount of O phase decreases gradually, while the grains of O precipitates become coarser. After PWHT, there are some thin acicular O precipitates in heat-affected zone (HAZ), and the decomposition of a2-phase caused by niobium diffusion can be observed in the HAZ. The PWHT can significantly increase the microhardness of joints, resulting from O phase precipitation hardening effect. The tensile strength and elongation of joints can be remarkably improved after PWHT, which was closely related to the strengthening effect of O precipitates and slip transmission between O and B2 phases. In addition, the results indicate that the best mechanical properties can be achieved only when the number and size of O phase and B2 phase are the best match.
关键词： Ti-24Al-15Nb alloy,microstructure,postweld heat treatment,mechanical properties,laser beam welding
更新于2025-09-12 10:27:22
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Effects of Stress-Relieving Heat Treatment on Impact Toughness of Direct Metal Laser Sintering (DMLS)-Produced Ti6Al4V (ELI) Parts
摘要： The impact toughness of as-built (AB) and stressed-relieved (SR) direct metal laser sintering-produced Ti6Al4V (ELI) was investigated using the standard Charpy impact test over the temperature range of ?130°C to 250°C. Stress-relieving heat treatment was conducted at 650°C for a soaking period of 3 h in argon gas atmosphere. The results showed improvements in the impact toughness after stress-relieving heat treatment. Stress relieving also shifted the established ductile-to-brittle transition temperature to lower temperatures. Comparative analysis of the impact toughness values for AB and SR specimens at ambient temperature showed them to be 48% and 22% lower than recommended values for use in aircraft structures, respectively.
关键词： Impact Toughness,Stress-Relieving Heat Treatment,Ti6Al4V (ELI),Direct Metal Laser Sintering,Charpy Impact Test
更新于2025-09-12 10:27:22
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Eliminating continuous grain boundary α phase in laser melting deposited near β titanium alloys by heat treatment
摘要： Continuous grain boundary α phase (αGB) is widely present in laser melting deposited near β and β titanium alloys, and it can lead to intergranular fracture and low ductility. Because of the preferential nucleation and growth of α phase at β grain boundaries, the continuous αGB cannot be effectively eliminated by traditional heat treatment. Thus, in this study, we develop a new heat treatment including beta solution + ultra-slow furnace heating up + traditional heat treatment, to eliminate continuous αGB in laser melting deposited Ti-5Al-5Mo-5V-1Cr-1Fe near β titanium alloy, and the microstructures and tensile properties are investigated. The results indicated that, after beta solution + normal heating up + traditional heat treatment, the continuous αGB still exists, and the elongation is still low about 7.5%. However, after beta solution + ultra-slow heating up + traditional heat treatment, there are almost no continuous αGB, and the elongation increases to 15.2%. The mechanism about the αGB formation during ultra-slow heating up process is simply revealed. Furthermore, this new heat treatment is also suitable to eliminate continuous αGB for laser melting deposited Ti17 alloy.
关键词： ductility,continuous grain boundary α phase,laser melting deposition,heat treatment,near β titanium alloys
更新于2025-09-12 10:27:22
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Influence of a local laser heat treatment on the bending properties of aluminium extrusion profiles
摘要： Driven by ecological and economical demands, lightweight design and in this context, the substitution of steel by aluminium has become a major trend in the automotive industry. However, design possibilities are limited by the low formability of aluminium alloys. One approach to overcome these limitations is the usage of tailor heat treated semi-finished products. By a local short-term heat treatment, distinct areas are softened, which can be used to improve the material flow into critical forming zones. Within this work, the influence of local short-term heat treatment on the formability of aluminium extrusion profiles is analysed by experimental bending tests. Aims are the enhancement of maximum reachable bending angles as well as the reduction of cross section deformations. Therefore, different heat treatment layouts are applied by laser irradiation. Finally, the bending results are evaluated and promising heat treatment strategies are derived.
关键词： heat treatment,bending,extrusion profiles,aluminium
更新于2025-09-12 10:27:22
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Additive manufacturing of tool steel by laser metal deposition
摘要： In this work, different geometries were additively manufactured applying laser metal deposition using powder out of hot-working tool steel 1.2344. It was shown that this hot working tool steel can be used to manufacture crack free parts through laser metal deposition. Temperatures were locally measured in experimental investigations. Additional microstructure analysis of different geometries indicated a dendritic solidification structure and grain boundary carbides. Vickers hardness varied between 400 HV 1 and 750 HV 1.
关键词： intrinsic heat treatment,1.2344,additive manufacturing,laser metal deposition,hot work tool steel,dilatometer specimen
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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Modeling the Temperature Distribution during Laser Hardening Process
摘要： A mathematical model was developed and is presented here to calculate the temperature distribution on the surface and bulk of a steel plate under the laser hardening process. The model starts from the basic heat equation, is then developed to a volumetric form and is connected to the various solid phases existing. The model is based on three strongly influencing parameters of the laser hardening process: velocity of the laser spot and irradiation time. The results are compared to the available experimental data reported in the literature. The volumetric model provides an assessment of temperature distribution in both the vertical and horizontal axis. Laser irradiation at sufficiently high fluence can be used to create a solid state phase change on the surface. Primary calculations show that the temperature profile has a Gaussian distribution in horizontal x-and y-axis and presents an exponentially decreasing distribution in the horizontal and vertical depth directions.
关键词： Laser hardening,heat treatment,Solid phase transformation,Temporal-temperature profile
更新于2025-09-12 10:27:22