Multi-Material Processing By Lens

During the past few years, solid freeform fabrication has evolved into direct fabrication of metallic components using computer aided design (CAD) solid models. [1-4] Laser Engineered Net Shaping (LENS™) is one such technique [5-7] being developed at Sandia to fabricate high strength, near net shape metallic components. In the past two years a variety of components have been fabricated using LENS™ for applications ranging from prototype parts to injection mold tooling. [8] To advance direct fabrication capabilities, a process must be able to accommodate a wide range ofmaterials, including alloys and composites. This is important for tailoring certain physical properties critical to component performance. Examples include graded deposition for matching coefficient ofthermal expansion between dissimilar materials, layered fabrication for novel mechanical properties, and new alloy design where elemental constituents and/or alloys are blended to create new materials. In this paper, we will discuss the development ofprecise powder feeding capabilities for the LENSTM process to fabricate graded or layered material parts. We also present preliminary results from chemical and microstructural analysis.Mechanical Engineerin

Laser engineered net shaping (LENS) for the repair and modification of NWC metal components.

Laser Engineered Net Shaping{trademark} (LENS{reg_sign}) is a layer additive manufacturing process that creates fully dense metal components using a laser, metal powder, and a computer solid model. This process has previously been utilized in research settings to create metal components and new material alloys. The ''Qualification of LENS for the Repair and Modification of Metal NWC Components'' project team has completed a Technology Investment project to investigate the use of LENS for repair of high rigor components. The team submitted components from four NWC sites for repair or modification using the LENS process. These components were then evaluated for their compatibility to high rigor weapons applications. The repairs included hole filling, replacement of weld lips, addition of step joints, and repair of surface flaws and gouges. The parts were evaluated for mechanical properties, corrosion resistance, weldability, and hydrogen compatibility. This document is a record of the LENS processing of each of these component types and includes process parameters, build strategies, and lessons learned. Through this project, the LENS process was shown to successfully repair or modify metal NWC components

LENS repair and modification of metal NW components:materials and applications guide.

Laser Engineered Net Shaping{trademark} (LENS{reg_sign}) is a unique, layer additive, metal manufacturing technique that offers the ability to create fully dense metal features and components directly from a computer solid model. LENS offers opportunities to repair and modify components by adding features to existing geometry, refilling holes, repairing weld lips, and many other potential applications. The material deposited has good mechanical properties with strengths typically slightly higher that wrought material due to grain refinement from a quickly cooling weld pool. The result is a material with properties similar to cold worked material, but without the loss in ductility traditionally seen with such treatments. Furthermore, 304L LENS material exhibits good corrosion resistance and hydrogen compatibility. This report gives a background of the LENS process including materials analysis addressing the requirements of a number of different applications. Suggestions are given to aid both the product engineer and the process engineer in the successful utilization of LENS for their applications. The results of testing on interface strength, machinability, weldability, corrosion resistance, geometric effects, heat treatment, and repair strategy testing are all included. Finally, the qualification of the LENS process is briefly discussed to give the user confidence in selecting LENS as the process of choice for high rigor applications. The testing showed LENS components to have capability in repair/modification applications requiring complex castings (W80-3 D-Bottle bracket), thin wall parts requiring metal to be rebuilt onto the part (W87 Firing Set Housing and Y-12 Test Rings), the filling of counterbores for use in reservoir reclamation welding (SRNL hydrogen compatibility study) and the repair of surface defects on pressure vessels (SRNL gas bottle repair). The material is machinable, as testing has shown that LENS deposited material machines similar to that of welded metal. Tool wear is slightly higher in LENS material than in wrought material, but not so much that one would be concerned with increased tooling cost. The LENS process achieved process qualification for the AY1E0125 D-Bottle Bracket from the W80-3 LEP program, and in the effort, also underwent testing in weapons environments. These tests included structural dynamic response testing and drop testing. The LENS deposited parts were compared in these tests with conventionally machined parts and showed equivalency to such an extent that the parts were accepted for use in parallel path subsystem-level weapon environment testing. The evaluation of LENS has shown that the process can be a viable option when either complete metal parts are needed or existing metal parts require modification or repair. The LENS Qualification Technology Investment team successfully investigated new applications for the LENS process and showed that it has great applicability across the Nuclear Weapons Complex as well as in other high rigor applications

Process qualification and testing of LENS deposited AY1E0125 D-bottle brackets.

The LENS Qualification team had the goal of performing a process qualification for the Laser Engineered Net Shaping{trademark}(LENS{reg_sign}) process. Process Qualification requires that a part be selected for process demonstration. The AY1E0125 D-Bottle Bracket from the W80-3 was selected for this work. The repeatability of the LENS process was baselined to determine process parameters. Six D-Bottle brackets were deposited using LENS, machined to final dimensions, and tested in comparison to conventionally processed brackets. The tests, taken from ES1E0003, included a mass analysis and structural dynamic testing including free-free and assembly-level modal tests, and Haversine shock tests. The LENS brackets performed with very similar characteristics to the conventionally processed brackets. Based on the results of the testing, it was concluded that the performance of the brackets made them eligible for parallel path testing in subsystem level tests. The testing results and process rigor qualified the LENS process as detailed in EER200638525A

Surfaces and Interfaces in Nanostructured Materials and Trends in LIGA, Miniaturization, and Nanoscale Materials: Fifth MPMD Global Innovations Symposium

This volume combines the proceedings of two prominent symposia presented by TMS\u27s Materials Processing and Manufacturing Division (MPMD). Papers from the Surfaces and Interfaces in Nanostructured Materials Symposium bring together experts working on different aspects of study, such as fabrication, characterization, modification, and modeling, to identify and address important issues, such as structure-chemistry-property relationships; surface engineering approaches in the nanoscale regime; chemistry and atomic bonding at interfaces; kinetics, diffusion paths, and related effects at interfaces; fabrication of bulk nanostructures; and advances in interfacial modification/engineering techniques. Proceedings from the Global Innovations Symposium on Materials Processing and Manufacturing: Trends in LIGA, Miniaturization, and Nanoscale Materials, the fifth in a series sponsored by the MPMD, provide description, insight, challenges, and projections for advances in miniaturized part manufacturing, evaluation, and applications. This collection provides a visionary look to where investments in materials research are likely to occur and what areas in materials R&D are ripe for discoveries that will have major impact on quality of life.https://corescholar.libraries.wright.edu/books/1018/thumbnail.jp

Surfaces and Interfaces in Nanostructured Materials and Trends in LIGA, Miniaturization, and Nanoscale Materials: Fifth MPMD Global Innovations Symposium

This volume combines the proceedings of two prominent symposia presented by TMS\u27s Materials Processing and Manufacturing Division (MPMD). Papers from the Surfaces and Interfaces in Nanostructured Materials Symposium bring together experts working on different aspects of study, such as fabrication, characterization, modification, and modeling, to identify and address important issues, such as structure-chemistry-property relationships; surface engineering approaches in the nanoscale regime; chemistry and atomic bonding at interfaces; kinetics, diffusion paths, and related effects at interfaces; fabrication of bulk nanostructures; and advances in interfacial modification/engineering techniques. Proceedings from the Global Innovations Symposium on Materials Processing and Manufacturing: Trends in LIGA, Miniaturization, and Nanoscale Materials, the fifth in a series sponsored by the MPMD, provide description, insight, challenges, and projections for advances in miniaturized part manufacturing, evaluation, and applications. This collection provides a visionary look to where investments in materials research are likely to occur and what areas in materials R&D are ripe for discoveries that will have major impact on quality of life

Understanding the microstructure and properties of components fabricated by laser engineered net shaping (LENS)

Laser Engineered Net Shaping (LENS) is a novel manufacturing process for fabricating metal parts directly from Computer Aided Design (CAD) solid models. The process is similar to rapid prototyping technologies in its approach to fabricate a solid component by layer additive methods. However, the LENS technology is unique in that fully dense metal components with material properties that are similar to that of wrought materials can be fabricated. The LENS process has the potential to dramatically reduce the time and cost required realizing functional metal parts. In addition, the process can fabricate complex internal features not possible using existing manufacturing processes. The real promise of the technology is the potential to manipulate the material fabrication and properties through precision deposition of the material, which includes thermal behavior control, layered or graded deposition of multi-materials, and process parameter selection. This paper describes the authors' research to understand solidification aspects, thermal behavior, and material properties for laser metal deposition technologies