AM Laser-directed energy(L-DED) deposition

Additive Manufacturing using Laser-directed energy(L-DED) deposition

1. Additive Manufacturing using Laser-directed energy(L-DED) deposition DINESH SHIVAKOTI (R01449875)

2. Outline Abstract Introduction Alloys Processed Energy Source in L-DED Resulting Structures Defects and Surface Quality Mechanical Properties Commercial Applications Pros and Cons Summary References

3. Abstract Laser Directed Energy Deposition (L-DED) is an advanced additive manufacturing (AM) technique that utilizes a focused laser beam to melt and deposit material—typically metal powder or wire—onto a substrate, building up components layer by layer. This process is particularly advantageous for producing large, complex parts and for repairing or enhancing existing components and it is notable for its ability to work with a variety of metal alloys, offering high precision and material efficiency. Image: Laser deposition process Image: Laser deposition process

4. Introduction What is L-DED? It is an additive manufacturing method that uses a high-power laser to melt and deposit materials layer by l ayer, onto a substrate. A high-power laser (e.g., fiber, CO₂, or diode laser) generates a molten pool on the surface of a substrate. Simultaneously, feedstock material, either in powder or wire form, is delivered into this melt pool through a nozzle or a feeder. The laser's energy melts the incoming material, which then solidifies upon cooling, forming a new layer. By precisely controlling the movement of the laser and the deposition head, intricate geometries can be constructed. Image: Schematics of L-DED setups; Powder-based process(left) and wire-based process(right)

5. Introduction Why choose L-DED? Laser-Directed Energy Deposition (L-DED) is a preferred additive manufacturing technique due to its high deposition rates, making it efficient for producing large-scale components. Unlike powder bed fusion methods, L-DED allows for  in-situ repair and recoating of existing parts, extending their service life and reducing material waste. Additionally, it is compatible with a wide range of alloys, including titanium, nickel-based superalloys, and stainless steels, making it highly versatile. L-DED is particularly valuable in industries like aerospace, defense, and medical manufacturing where complex geometries, high-performance materials, and rapid prototyping are required. Image: L-DED manufactured part (Image Source: https://additec3d.com) Image: Large part being manufactured using L-DED (Image Source: https://all3dp.com)

6. Alloys Processed Laser Directed Energy Deposition (L-DED) is c ompatible with a  wide range of alloys, making it highly versatile. Some of the alloys and their application are given below. Titanium Alloys (TC11/Ti-6Al-4V) – Aerospace, biomedical implants Nickel Superalloys (Inconel 625/Inconel 718) – Turbine blades, high-temperature applications Stainless Steels (316L) – Corrosion-resistant parts Copper Alloys(GRCop-42/GRCop-84) – NASA Rockets regeneratively cooled combustion chamber Aluminum Alloys (AlSi10Mg) – Lightweight structural components Cobalt-Chromium Alloys Image: Metal powder for 3d printing

7. Energy Source in L-DED The energy source in the Laser Directed Energy Deposition (L-DED) is a high-power laser beam. Commonly used Laser types are Fiber Lasers, Diode Lasers, CO2 Lasers. For powder-based machines, powder is dispensed into a carrier gas stream which transports it through tubes to the deposition head. The powder is then sprayed through a nozzle toward the substrate, and the laser is then activated, forming the weld pool. The nozzle and laser delivery system, referred to as the deposition head, is then moved through the programmed toolpath to weld on the feedstock material and to fabricate the component. For wire-based systems, the deposition head includes a wire-feeder system which properly locates and orients the wire so that it feeds into the weld pool. The weld pool is formed on the substrate by the laser at a prescribed and often variable feed-rate Image Source: https://www.cailabs.com

8. Resulting Structures Macro Structure The macrostructure of parts produced by L-DED typically shows a layered architecture because of the sequential deposition of material. Each layer partially melts the one beneath it, leading to good metallurgical bonding between layers. However, because of the rapid cooling and the additive nature of the process, there can be visible layer boundaries. The build orientation and toolpath strategy affect grain growth direction, leading to anisotropic properties in some cases. Unlike powder bed fusion (PBF), L-DED often has coarser layer resolution (100–500 µm), making it better suited for larger, near-net-shape parts rather than for fine-detail components. Microstructure Due to the rapid melting and solidification of the molten material, L-DED typically results in dendritic microstructure in the build direction. The cooling rate (which depends on laser power, scanning speed, and material) directly affects the grain size. The fast-cooling rates lead to fine microstructure(small grains, better mechanical properties). In some alloys, grains extend across multiple direction which can enhance mechanical properties along the build direction. Image: Layers in the AM part Image: Dendritic microstructure

9. Defects and Surface Quality Laser-directed energy deposition (L-DED) parts often exhibit surface roughness and various defects like voids, cracks, and porosity due to the high heat input and melt pool dynamics. However, advancements in process monitoring and parameter optimization, along with post-processing techniques, are improving surface quality and reducing defects. Porosity Caused by gas entrapment (hydrogen, nitrogen) or lack of fusion between layers. Can be minimized by optimizing shielding gas (argon/helium) and process parameters. Surface Roughness Typically, higher than PBF methods (10–50 µm), often requiring machining or polishing for final use. Unmelted powder particles and spatter can contribute to surface irregularities. Residual Stresses & Distortion Rapid heating and cooling induce thermal stresses, sometimes causing warping or cracking. Post-process stress-relief annealing or hot isostatic pressing (HIP) is often required for critical parts.   Image: Surface Roughness Image: Porosity under Microscope

10. Mechanical Properties Strength Comparable to conventionally manufactured material due to the resulting fine-grained microstructure. However, due to residual stresses and defects like porosity mechanical strength can drop but Post-processing such as heat treatment(HIP) is used often to improve strength. Example : Ti-6Al-4V (L-DED) can achieve UTS ~900–1100 MPa, like wrought material. Hardness Generally  higher than cast materials due to rapid cooling (e.g.,  316L SS: ~200–250 HV vs. ~180 HV for cast) Ductility Typically,  lower than wrought alloys  due to residual stresses and microstructural anisotropy. Post-processing (e.g., HIP, annealing) improves elongation Example: Ti-6Al-4V: 8–14% elongation  vs. ~15% for wrought). Fracture Toughness Fracture toughness (resistance to crack growth) is lower than forged parts due to the defects(e.g. lack of fusion, inclusions). Example: Ti-6Al-4V (L-DED) has ~40–60 MPa√m  vs. ~70 MPa√m for wrought.

11. Mechanical Properties Fatigue Resistance Fatigue properties are generally lower than those of wrought materials. Surface roughness, internal defects like porosity & inclusion can act as crack initiation sites. Surface finishing techniques like machining, polishing are often applied to improve fatigue life. Hot Isostatic Pressing (HIP) closes pores, improving fatigue life by 30–50%. Creep Resistance Nickel Superalloys like Inconel 718/625 show excellent creep resistance comparable to wrought at an elevated temperature. Image: Comparison with other AM methods

12. Commercial Applications L-DED is widely adopted across industries due to its high deposition rates, material flexibility, and ability to repair/add material to existing components. Below shows its key commercial applications: Aerospace Industry Turbine Blade & Engine Component Repair – depositing wear-resistant coatings(e.g. Inconel 718) on damaged areas. Rocket Nozzles & Combustion Chambers – Copper alloys are used in repairing the internal coolin g channel using L-DED. Automotive Industry Customized & High-Performance Components – lightweight, high-strength suspension/transmission parts in F1 cars. Tool and Dies – L-DED repairs molds and dies for extended service life. Rapid Prototyping – concept cars are prototyped faster than with traditional manufacturing methods. Medical Devices Custom Implants – L-DED is perfect for creating patient-specific implants (e.g., hip, knee, cranial plates) based on CT/MRI data. Materials such as Titanium (Ti-6Al-4V) are used because of their excellent biocompatibility and mechanical strength. Defense High-Strength, Complex-Geometry Parts – Missile components, armored vehicle parts, drone structures & Submarine parts

13. Pros and Cons Pros L-DED allows high deposition rates compared to other additive manufacturing process like PBF, making it suitable for larger parts manufacturing at high speed. It is known for being highly effective for repairing high-value parts like turbine blade, molds etc. extending their lifespan at lower cost than the replacement at less lead time. L-DED is more material flexible and can process wide range of metals/alloys. Since only the material required for the part is deposited, It reduces material cost and leads to significant cost saving. It is capable of multi-material deposition(e.g., graded structures) useful in aerospace and medical industries. Cons L-DED machines are very expensive to purchase, operate and maintain , making it less viable for small business. Parts created using L-DED has high surface roughness and often require machining, polishing or heat treatment (e.g., HIP) to improve mechanical properties. Compared to other AM methods like SLM, L-DED parts has lower dimensional accuracy limiting its use for parts with micro features. L-DED parts are likely to have porosity, cracks and residual stress which can affect mechanical properties. L-DED parts exhibit anisotropic properties due to layer-by-layer deposition and columnar grain growth.

14. Summary Laser-Directed Energy Deposition (L-DED) is an advanced additive manufacturing technique that uses a high-power laser to melt and deposit metal powders or wires layer-by-layer.  L-DED is a versatile AM method for high-performance metal parts and works with Ti, Ni, Steel, Copper alloys for aerospace, automobile, medical and defense applications.  L-DED offers advantages like higher deposition rate to manufacture larger parts, repair capabilities, reduce material waste.  While post-processing is often necessary, advancement in the process control/optimization is making it better continuously. It can be coupled with CNC machining for hybrid manufacturing for high precision, large-scale parts.

15. References 1. Directed energy deposition GRCop-42 copper alloy: Characterization and size effects https://doi.org/10.1016/j.matdes.2022.111035 2. Microstructure evolution and performance improvement of 42CrMo steel repaired by an ultrasonic rolling assisted laser directed energy deposition IN718 superalloy https://doi.org/10.1016/j.jallcom.2025.180385 3. Influence of laser power on the forming quality of Al 2 O 3  ceramic in directed energy deposition https://doi.org/10.1016/j.ceramint.2025.02.204 4. Improvement of microstructure and mechanical properties of Inconel718 by the synergistic strategy of laser power and interlayer temperature control in laser directed energy deposition https://doi.org/10.1016/j.optlastec.2025.112715 5. Understanding of microstructure and mechanical properties of heat-treated Ti 3 SiC 2 /Inconel 625 matrix composites manufactured by laser-directed energy deposition https://doi.org/10.1016/j.jmrt.2025.04.147 6. Multi laser beams directed energy deposition of a high-strength and high-toughness TC11 titanium alloy with coaxial wire feeding https://doi.org/10.1016/j.nxmate.2025.100576 7. Application of hot wire laser directed energy deposition for efficient fabrication of large nickel-based alloy components: Process, microstructure, and mechanical properties https://doi.org/10.1016/j.jmatprotec.2025.118789 8. Microstructure and properties of 316L- yttrium stabilized zirconia composites by laser directed energy deposition https://doi.org/10.1016/j.jallcom.2025.180235 9 . Microstructure and mechanical properties of nickel-based 625 alloy fabricated using high-speed laser direct energy deposition https://doi.org/10.1016/j.msea.2025.148164 10. Review of Advanced Manufacturing Techniques: Laser-Directed Energy Deposition Additive Manufacturing