Metal Additive Manufacturing For Aerospace Markets - EWI

Metal Additive Manufacturing for Aerospace Markets 7th International EWI/TWI Aerospace Seminar, Seattle, WA Sept 17-18, 2014 Ian D. Harris, Ph.D. Technology Leader, Arc Welding Founding Director, Additive Manufacturing Consortium iharris@ewi.org , 614.688.5131 Shawn Kelly, Ph.D. Senior Engineer, Additive Manufacturing and Lasers Director, Additive Manufacturing Consortium skelly@ewi.org , 614.688.5145 1

Outline Existing and emerging metal AM processes and capabilities Associated priorities for manufacturing transition; Property data In-process monitoring NDE EWI capability, role, and interactions Summary 2

Advanced Manufacturing Technologies at EWI Innovate, mature, commercialize Materials Joining and Manufacturing technology for industry AcousTech Machining Additive Manufacturing Advanced arc welding Automation, sensors, controls Brazing and soldering Dissimilar materials joining Friction processing Hot forming Laser processing Nondestructive evaluation Numerical modeling and simulation Plastic and composite fabrication Resistance welding Ultrasonic joining Weldability and mechanical testing; metallurgical analysis

AM is Materials Joining Manufacturing of complex 3D parts by joining successive layers 1-inch L-PBF Cube 675 feet of weld (Audi R8) 3,400 feet of weld 5 miles of weld 4

AM Processes for Metals Laser and EB powder bed, from e.g. EOS, and Arcam in confined envelope (g/hr) – Primary AMC focus is PBF-L EBW freeform fabrication - EB(FFF) (kg/hr) Laser powder and wire FFF from companies such as POM, Optomec (LENS), EFESTO (kg/hr) VHP UAM – very high power ultrasonic AM of strip – Fabrisonic (kg/hr) Emerging - Arc processes – SMD, MER, GTAW-HW (EWI IRD), GMAW-P, PTA (wire and powder) based on commercially available equipment for FFF (kg/hr)

Deposition Rate vs Resolution Increased Deposition Rate Courtesy Boeing Large FFF parts ‘Big metal’ e.g. aero structure GTAW-HW and other arc processes EBFFF VHP UAM LAM Decreased Resolution Small intricate parts- e.g complex fuel nozzle – PBF-L and PBF-EB

Example Aerospace Applications EB FFF and laser powder (DMLS) parts LM Aero calculate 50% cost reduction for Ti6-4 EBFFF versus forging for ‘flaperon’ spar

A new paradigm in LMD from RPM/EFESTO 87-in 92.2 m) high part in Ni-based alloy 8

Mori- Seiki CNC build and machine http://www.youtube.com/watch?v aUX Hm01KMc 1.65M CNC system with LAM build and integrated machining to produce a finished part? I steels and austenitic stainless steels such as 304L maybe, but for Ni-based alloys, Ti-based alloys, will still need PWHT and finishing/machining 9

EWI Activities in AM AM is a technology area at EWI. Expertise in lasers, materials, NDI, sensing and controls, design, fusion welding (arc, laser, EB), modeling, and ultrasonics. Focus Areas Metals Laser Powder Bed Fusion (EOS M280 DMLS) Material/Process/Property Development Complete Supply chain (materials, heat treatment, inspection) In process sensing. Other AM Process Areas Arc-Based AM, Ultrasonic AM, Laser Directed Energy Deposition Repair AM Operate the Additive Manufacturing Consortium Innovative Ceramics and Polymer AM at EWI-NY. 10

Ultrasonic Additive Manufacturing Solid state, full metallurgical bond Enables multi-material-system, multi-functional AM with embedded function Excels in materials that are difficult to fusion weld (Al Ti, etc.) Up to 6’x6’x3’ (2mx2mx1m)envelope with 5 axis CNC machining (3 sizes) Developed by EWI and spun off as a for-profit machine manufacturer. http://www.fabrisonic.com/

Capabilities: Robotic Arc Based AM AM is not limited to laser or electron beam equipment for FFF. Robotic arc based deposition methods: Readily available equipment – transitioning to full robotic AM, CAD to part Still requires much of the process control infrastructure needed for laser and EB AM processes. Deposition rates from 1 in3/hr to 100’s in3/hr, up to 40 lbs/hr Serves aerospace and additional defense/commercial markets GTAW (Hot Wire) Five beads on a 1.6 mm edge GMAW-RWF Defense ground vehicle 80 lb. build in Ti-6-4 using GTAWHW Nuclear component Wing stiffener/rib Using GMAW-P

GTAW-HW for AM at EWI Recent work GTAW-HW for Ti-6-4 ELI (AWS WJ March 2014) Full AM (CAD to part) robotic deployment 13

GTAW-HW for FFF Table 1. Composition of Hydrogen, Nitrogen, and Oxygen in the Weld Deposit, Along with the Nominal Composition in Ti 6-4 ELI Castings, and the Maximum Permissible Composition in Ti 6-4 ELI Forgings (Met all requirements) Element Actual Composition (wt%) Hydrogen Nitrogen Oxygen 0.0013 0.0078 0.077 Nominal Composition for Ti 6-4 ELI Castings(1) (wt%) 0.006 0.010 0.11 Maximum Permissible Composition for Ti 6-4 ELI Forgings(2) (wt%) 0.0125 0.03 0.13 Table 2. Tensile Test Data for the Sub-Sized Specimens Along with Typical Tensile Test Properties of Bars Machined from Ti 6-4 ELI Castings (Initial work, close to requirements) ID Baselin e 1 2 3 4 5 6 7 8 9 10 11 12 Specimen Orientation Condition Tensile Strength (ksi) Yield Strength (ksi) Elongation (%) Reduction in Area (%) N/A Typical values for a Ti 6-4 ELI castings(1) 120 110 13 22 124.5 116.1 105.8 106.1 123.0 122.0 119.2 117.4 101.8 103.3 116.9 124.7 10.9 9.3 14.5 13.7 12.9 9.4 9.7 10.9 13.3 12.2 8.1 11.0 31.9 25.6 26.5 28.6 18.9 20.0 28.8 38.0 26.5 31.8 20.0 21.1 Weld Direction As-welded Weld Direction Solution heat treatment anneal Weld Direction Anneal Build Direction As-welded Build Direction Solution heat treatment anneal Build Direction Anneal 137.0 133.4 115.2 116.8 135.6 135.3 136.3 134.6 113.6 113.2 132.6 135.6 14

6-9 axis robotic AM with arc and laser welding and EBFFF Hawk Gantry for large aerospace parts using arc and 20 kW laser capability (Ar/non-vacuum) Sciaky EBFFF for F-35 JSF (vacuum) 15

EWI Capabilities: Laser Powder Bed Fusion Heat Exchanger EOS M280 at EWI Enables complex 3D shapes Internal passages for cooling, light-weighting Properties comparable to conventional (depending on alloy and heat treatment, and surface condition) As built surface finish 100-200 µin Argon or Nitrogen Environment Challenges: Building on non planar surfaces Composition grading Titanium Spinal Implant

Addressing Technical Gaps in L-PBF and AM Technology Development of custom process parameter sets for existing or new alloys. (EWI is a materials development partner with EOS). Holistic Approach to AM Understanding of the complete manufacturing chain, including heat treatment, material understanding, feedstocks, distortion, material properties, etc. Development of material property data of a known pedigree. Next generation process equipment in-process sensing productivity enhancements. Downstream manufacturing operations: non-destructive inspection, assembly/weldability of AM components. Prototype production when one of the above areas is involved. EWI maintains relationships with several market specific service providers to transition results to practice. 17

Additive Manufacturing Supply Chain Process Selection CAD File Process Sensing Material Path Planning Process Control Inspection Thermal History Residual Stress Dimensional Control AM Process Finishing Heat Treatment Material Properties Final Part Qualification & Certification Blue boxes are being addressed at EWI presently

EWI is an EOS Materials Development Partner EWI offers understanding of process and material interaction, from a welding and AM perspective. Currently 11 materials for EOS. Represent low-hanging fruit for EOS business model. EOS ‘controls’ parameter set/material combinations. Over 70 parameters that define a process. Limited EOS development capability in the US. EWI has developed parameters for tungsten, 420SS, 4140 steel, 316L stainless. Orders for other refractory metals and alloys in queue. Downhole Drill Bit in 420 SS 4140 Steel 420 Stainless

M&P Understanding: Thermal History Impacts Microstructure and Properties Geometrically equivalent parts (Ti-6Al-4V), produced by scanning in two orientations. Microstructurally different - different properties. Scan Direction Fraction Colony Alpha Impact on Property Long Axis High Strength, Reduced Toughness Short Axis Reduced Strength, Greater Toughness

Property Database Generation Problem Statement: Methods for generating pedigreed property data for AM do not exist Objective: Develop data generation methods and documentation and begin to form a foundational dataset. Nickel Alloy 625 NIST and Additive Manufacturing Consortium funding Cannot overlook heat treatment. Conventional heat treatment needed to be modified. Round robin testing (machine to machine, vendor to vendor) 400 MPa Range

Outcomes 33 Page Manufacturing Plan Four 200 Hour Builds Heat Treatment Study RT and Elevated Temp Testing

Nickel Alloy 718 Heat Treatment Development Problem Statement: Application of conventional nickel alloy 718 heat treatments to L-PBF material are not fully understood or optimized. Objective: Evaluate the heat treatment response of nickel alloy 718 produced using EOS M280 to define future heat treatment optimization. Apply approach from 625 project. Evaluate the conventional heat treatment response of 718 Tensile and creep properties at 650 C (1200 F) Material characterization information that will allow improved understanding of the impact of the process on material performance. Phase 1 1 year As-built SR ST Age

In Process Sensing: NIST MSAM Program National Additive Manufacturing Innovation Institute Problem Statement: L-PBF equipment lacks robust manufacturing quality controls that conventional manufacturing employs. Objective: Develop a robust, informative in-situ process monitoring capability standard for AM. Provide QA/QC ‘Inspect the un-inspectable.’ Facilitates sensor screening and future machine design Part 21 Part 1 Part 1 Part 21?. at Layer 1 through 2000?

Overall Objective of the NIST MSAM program is to Measure and Certify Build Quality National Additive Manufacturing Innovation Institute

Sensor Test Bed Don’t limit process sensing because of constraints. Replicate important characteristics of the commercial process. Provide adequate space. Avoids problem of physical and software constraints

Sensor Test Bed Development and Build (EWI)

Sensor Matrix Local Photodetector X Spectrometer X High Speed Video Global Passive Volumetric Defects X X Defect Generation Understanding Thermal Imaging High Resolution Imaging X X X Laser Line Scanner X X X Thermal Imaging Photogrammetry (UNCC) X X Projection Moiré (UNCC) X X Acoustic Metallurgical Bed Flatness Geometry Distortion Sensor Process Deviation Process Observation Defect Type X X X X X X X X Ultrasonic X Interferometer X

Challenges and Path Forward BIG Challenge BIG Data throughput, processing/distillation, go/no-go, storage Global Imaging with 10MP camera: 9.6 GB Local sensing: measurement every beam width 80M data points Path Forward Complete assembly and verify build conditions (May/June) Install and test sensors (Summer) Data processing (Fall) Downselect viable sensors (Winter) EWI is leading two other programs for in process sensing for L-PBF and L-DED

Post Process Inspection: Material/Geometry Issues National Additive Manufacturing Innovation Institute Problem Statement for Materials: Ultrasonic inspection limits of Ti-6Al-4V produced by certain AM techniques reduced by complex microstructure. Objective: Address reduced ultrasonic inspectability of heat treated Ti-6Al-4V Process modifications Improved Matrix Phased Array Ultrasonic Inspection Needed for transition. If unresolved, reliance on radiography and increase in inspection burden (additional cost/time). Problem Statement for Geometry: Geometric complexity of AM parts limits application of many conventional NDI techniques. Objective: Identify means to quantify inspectability based upon geometry and current state of the art capability. Thick to thin ( Density Differences ) Embedded features Thickness of the build layers (40 Micron) Organic Part Design