Directed Energy Deposition Research Articles

Effect of powder-feeding process on metal transfer mode and microstructural evolution of wire–powder–arc directed energy deposition-manufactured aluminum alloys

ABSTRACT Wire–powder–arc directed energy deposition (WPA-DED) technology offers significant potential for alloy development and the production of large, complex-graded material parts due to its capability for in situ deposit composition adjustment. However, the effect of the powder-feeding process on formation stability and microstructure development remains unclear. In this study, ER2024 wire and Al-4.44Cu-1.53Mg and Al-4.50Mg-0.65Sc-0.29Zr powders were used to form thin-wall samples. Quasi-static analysis of forces on molten droplets revealed that increased gas flow induced the formation of larger droplets. Infrared thermography identified changes in solidification conditions at different heights and gas flow rates, showing that lateral powder-feeding gas increased the horizontal temperature gradient at the molten pool’s top. This promoted horizontal columnar grain growth while suppressing vertical growth at the base, resulting in a bimodal microstructure. Applying columnar-to-equiaxed transition (CET) theory further showed that powders with heterogeneous nucleation elements refined the grain structure, yielding a uniform, fully equiaxed structure. These findings provide a basis for optimising WPA-DED processes and improving microstructural control and mechanical property.

Interface Optimization, Microstructural Characterization, and Mechanical Performance of CuCrZr/GH4169 Multi-Material Structures Manufactured via LPBF-LDED Integrated Additive Manufacturing

CuCrZr/GH4169 multi-material structures combine the high thermal conductivity of copper alloys with the high strength of nickel-based superalloys, making them suitable for aerospace components that require efficient heat dissipation and high strength. However, additive manufacturing of such dissimilar metals faces challenges, with each laser powder bed fusion (LPBF) and laser directed energy deposition (LDED) process having its limitations. This study employed an LPBF-LDED integrated additive manufacturing (LLIAM) approach to fabricate CuCrZr/GH4169 components. CuCrZr segments were first produced by LPBF, followed by LDED deposition of GH4169 layers using optimized laser parameters. The microstructure, composition, and mechanical properties of the fabricated components were analyzed. Results show a sound metallurgical bond at the CuCrZr/GH4169 interface with minimal porosity and cracks (typical defects at the interface), achieved by exceeding a threshold laser energy density. Elemental interdiffusion forms a 100–200 μm transition zone, with a smooth hardness gradient (97 HV0.2 to 240 HV0.2). Optimized specimens exhibit tensile failure in the CuCrZr region (234 MPa), confirming robust interfacial bonding. These findings demonstrate LLIAM’s feasibility for CuCrZr/GH4169 and underscore the importance of balancing thermal conductivity and mechanical strength in multi-material components. These findings provide guidance for manufacturing aerospace components with both high thermal conductivity and high strength.

Linking directed energy deposition process toolpaths to FEM to study the toolpath/geometry role on residual stress formation for multi-layer components

Purpose This paper aims to investigate the use of the element-birth-and-death technique within the finite element method (FEM) to analyze direct energy deposition (DED) processes, an additive manufacturing (AM) technique. The focus is on understanding the interaction between different geometries and toolpaths in multi-layer depositions and establishing a foundation for generating optimal tool paths. The long-term goal of this research is optimizing thermal and structural performance, minimizing residual stress and improving overall part quality. Design/methodology/approach This study integrates DED toolpath vectors from process planning software into ANSYS to conduct thermal and structural analyses. This novel integration of design and process simulation enables a more accurate prediction of part quality. Four geometries and three toolpath strategies were analyzed, requiring the computational mesh domain to adapt to the toolpath characteristics. Experimental measurements validated the model, and the influence of dwell time intercooling on residual stress formation was explored. The research also compared the effects of various toolpath strategies and deposition patterns on the mechanical properties of the parts, highlighting the importance of toolpath generation for subsequent process certification and qualification activities. Findings The results show that shorter beads with longer dwell times lead to better part quality compared to longer beads with shorter laser-off intervals. A transverse deposition with identical dwell times produced the best part quality, despite requiring longer build times. In addition, frequent laser-off cycles were less effective at reducing high residual stress areas but resulted in lower average tensile stresses at mid-layers, though these cycles pose challenges for powder-based systems. This analysis helps in benchmarking and enhancing DED as an AM process. Originality/value This study offers a novel method of integrating DED toolpath characteristics into FEM-based simulations, providing valuable insights into the thermal and mechanical behavior of parts under various toolpath and geometry configurations. The research contributes to advancing the design-for-AM paradigm by demonstrating the critical role of thermal management and toolpath directionality in minimizing residual stress. This foundational work will support further research into more complex geometries and hybrid manufacturing techniques, aiding in the industrialization and optimization of DED processes.

Influence of scanning speed and hatch distance on defects, microstructure, and mechanical performance of Fe–Mn–Al–Ni–C low-density steel fabricated via directed energy deposition

This study examined the effects of the directed energy deposition (DED) process parameters on the microstructural evolution, defect formation, and mechanical properties of Fe–Mn–Al–Ni–C low-density steel. The samples were fabricated in an Ar atmosphere by adjusting the scanning speed (600, 1000, 1400 mm/min) and hatch spacing (1.32, 1.11, 1.00 mm), and the influence of these process parameters on the porosity, microstructural characteristics, and compressive yield strength was analysed systematically. The experimental results showed that increasing the scanning speed and reducing the hatch spacing (1400 mm/min, 1.00 mm) decreased the amount of unmelted powder on top of the melt pool, reduced surface roughness, and significantly lowered the overall porosity. Under these conditions, however, the increased heat input reduced the cooling rate of the melt pool, promoting the growth of the ferrite/B2 (BCC) phase. This weakened the secondary phase strengthening effect, reducing the compressive yield strength (1058.02 ± 17.33 MPa). In contrast, a lower scanning speed (600 mm/min) and a larger hatch spacing (1.32 mm) accelerated the cooling rate of the melt pool and suppressed the growth of the ferrite/B2 phase, resulting in a fine and uniformly distributed microstructure and enhanced compressive yield strength (1183.02 ± 23.56 MPa). This study revealed the complex relationship between the DED process parameters, microstructure, porosity, and yield strength, providing a theoretical foundation and practical guidance for further optimising the forming process and improving the overall performance of this alloy.

Possibilities of Evaluating the Quality of Products Produced by Directed Energy Deposition Technology

Possibilities of Evaluating the Quality of Products Produced by Directed Energy Deposition Technology

Microstructure and Mechanical Properties of Dual‐Phase FeCoCrNiAl0.6 High Entropy Alloys Prepared by Laser Directed Energy Deposition

Recently, dual‐phase high‐entropy alloys with excellent strength–ductility combination have attracted widespread attention in the scientific community. Herein, three dense and crack‐free dual‐phase FeCoCrNiAl0.6 high entropy alloys (HEAs) were successfully prepared by laser directed energy deposition (LDED) via adjusting laser scanning speed. The alloys printed have formed fine columnar face‐centered cubic (FCC) dendrites and woven mesh body‐centered cubic (BCC) interdendrites. The BCC phase is further composed of nanoscale A2 and B2 phases formed by spinodal decomposition. As the laser scanning speed increased from 5 mm s−1 to 9 mm s−1, the fraction of FCC phase increased from 56.9 to 70.5%, and the size of FCC dendrites refined. The sample printed at 9 mm s−1 with an average grain size of 3.9 μm showed a comprehensive mechanical property, namely, a high yield stress and ultimate tensile stress (712.0 and 1121.9 MPa) and a total elongation of 16.5%. The fracture surface changed from a cleavage‐type facet to ductile dimples as the laser scanning speed increased. Based on the microstructures of base materials, it can be concluded that the fine microstructure and soft FCC phase can prevent the initiation and propagation of microcracks and, thereafter, alleviate the brittle failure.

A critical overview of welding and directed energy deposition with flux-cored wires

A critical overview of welding and directed energy deposition with flux-cored wires

NiTi alloys with simultaneous equiaxed-grain strength and columnar-grain ductility manipulated by direct energy deposition

NiTi alloys with simultaneous equiaxed-grain strength and columnar-grain ductility manipulated by direct energy deposition

Dynamic deformation response of maraging steel 250 produced through directed energy deposition: Deformation behavior and constitutive model

Dynamic deformation response of maraging steel 250 produced through directed energy deposition: Deformation behavior and constitutive model

Synergistic effect of boron and nitrogen on strength enhancement and anisotropy mitigation in Ti6Al4V fabricated via directed energy deposition

Synergistic effect of boron and nitrogen on strength enhancement and anisotropy mitigation in Ti6Al4V fabricated via directed energy deposition

Crack mitigation at interface between Inconel 718 and stainless steel 316L during directed energy deposition under N2 atmosphere

Crack mitigation at interface between Inconel 718 and stainless steel 316L during directed energy deposition under N2 atmosphere

Effect of laser power on the microstructure and mechanical properties of heat-treated ATI 718Plus superalloy through direct energy deposition

Effect of laser power on the microstructure and mechanical properties of heat-treated ATI 718Plus superalloy through direct energy deposition

Dynamic laser beam shaping by means of a deformable mirror to tailor microstructure in Directed Energy Deposition

Dynamic laser beam shaping by means of a deformable mirror to tailor microstructure in Directed Energy Deposition

Microstructural and interfacial characteristics in repair of nickel-aluminum bronze by in-situ synthesis of Cu-Al alloys via directed energy deposition

Microstructural and interfacial characteristics in repair of nickel-aluminum bronze by in-situ synthesis of Cu-Al alloys via directed energy deposition

Numerical and experimental study to reduce powder segregation in directed energy deposition using ultrasonic vibration AlSi10Mg/Cu powder feeding

Numerical and experimental study to reduce powder segregation in directed energy deposition using ultrasonic vibration AlSi10Mg/Cu powder feeding

Productive Energy Fluence (PEF) controller using feed and laser hybrid control for Directed Energy Deposition (DED)

Productive Energy Fluence (PEF) controller using feed and laser hybrid control for Directed Energy Deposition (DED)

Effect of laser-induced protective materials/rare earth boride double protection structure on the microstructure and properties of multi-pass ER2209 underwater direct laser energy deposition coating

Effect of laser-induced protective materials/rare earth boride double protection structure on the microstructure and properties of multi-pass ER2209 underwater direct laser energy deposition coating

Tailoring microstructure in functionally graded NiTi alloys using in-situ alloying directed energy deposition

Tailoring microstructure in functionally graded NiTi alloys using in-situ alloying directed energy deposition

Wire-influenced particle dynamics and fluid flow behaviors of melt pool in coaxial wire-powder fed directed energy deposition of metal matrix composites

Wire-influenced particle dynamics and fluid flow behaviors of melt pool in coaxial wire-powder fed directed energy deposition of metal matrix composites

Microstructure evolution and performance improvement of 42CrMo steel repaired by an ultrasonic rolling assisted laser directed energy deposition IN718 superalloy

Microstructure evolution and performance improvement of 42CrMo steel repaired by an ultrasonic rolling assisted laser directed energy deposition IN718 superalloy