Wednesday, October 26, 2016, Room 355A
Jim Craig, President of Stratonics, will present two briefings at the MS&T 2016 Conference; “Thermal Control to Achieve Consistent and Uniform Mechanical Properties” and “The Effect of Global Heat Control on Melt Pool Temperature and Size“. Additional research will be presented by organizations implementing Stratonics ThermaViz® Sensor Technology. Final Program
STRATONICS PRESENTATIONS at MS&T
Thermal Control to Achieve Consistent and Uniform Mechanical Properties: James Craig1; Edward Reutzel2; Abdalla Nassar2; 1Stratonics, Inc.; 2ARL/Penn State University
A current challenge in additive manufacturing of Ti-6Al-4V is the difficulty inherent in relating process parameters and in-situ thermal conditions to melt pool geometry and mechanical properties. Here experimental results for thin wall geometries generated via the Optomec LENS system are considered in an effort to validate theoretical relationships between thermal conditions at solidification and resultant mechanical properties. In these experiments, the effect of changing substrate thermal energy is studied on the Vickers hardness, VH, profile. The substrate thermal energy was controlled by adjusting the interlayer time delay to achieve a cooler condition than achieved without control, e.g. with zero interlayer time delay. Further, the VH profile along the deposit, bottom to top, was measured for various control parameters. The controlled deposits had increased hardness and improved uniformity.
The Effect of Global Heat Control on Melt Pool Temperature and Size: James Craig1; Sarah Kuntz2; 1Stratonics, Inc.; 2Wright State Institute
Experiments were performed using an Optomec LENS machine in which a side viewing global heat sensor was used for thermal control of the deposit and a second sensor was used to measure the response of the melt pool. Thin walled geometries were deposited from Ti-6AL-4V. The delay time between layers was adjusted to control the total heat in the deposit. The hottest condition was achieved when the controller was not used and the interlayer delay was near zero. For the controlled deposits, the total heat in the deposit was set to about 50 and 30% of the hot level achieved without control. Hence the controlled deposits were cooler than the uncontrolled case. The control system produced highly stable and repeatable thermal conditions during the deposit and the melt pool sensor measured its response to varying thermal conditions, e.g. thermal set points.
ADDITIONAL PRESENTATIONS UTILIZING STRATONICS SENSOR TECHNOLOGY
In Situ Monitoring of Directed Energy Deposition: Cameron Knapp1; Thomas Lienert1; John Carpenter1; Desiderio Kovar2; 1Los Alamos National Laboratory; 2University of Texas at Austin
One definition of stability during additive manufacturing (AM) using directed energy deposition (DED) processes is that errors in layer thickness will self-correct rather than continue to propagate or magnify errors defined as the ability to precisely control the layer thickness of the deposit. Here we show that passive deposition stability for a DED system (Optomec LENSTM MR-7) is highly dependent on processing parameters. A set of experiments was conducted using ideal, two-dimensional deposition geometries in 304L stainless steel. The experiments were conducted with an array of diagnostic tools that allowed in situ monitoring of process conditions. Two thermographic sensors were used to measure spatial-temperature signals during deposition, a co-axial two-color pyrometer to monitor the molten pool with a spatial resolution of 10 – 20 µm, and a side-view infrared camera to track thermal and positional trends across multiple layers. Measured data revealed that the peak molten pool temperature increased linearly at 6.67°C/pass, the cooling rate stayed relatively constant around 1.55×104 °C/s, the heating rate increased linearly up until 25 passes where it plateaued, and the molten length and width increase linearly at 4μm/pass and 5.5μm/pass respectively. These extracted deposition features of the molten pool and the fabricated geometry are the basis for developing key features to extract for eventual implementation in a closed-loop-control architecture.
Integrated Process Monitoring Physics-based Modeling Approach for Uncertainty Quantification in Metal-based Additive Manufacturing: Alaa Elwany1; Raymundo Arroyave1; Ibrahim Karaman1; Ji Ma1; Gustavo Tapia1; Brian Franco1; Kubra Karayagiz1; 1Texas A&M University
Accelerating the qualification and certification (Q&C) of additively manufactured part remains to be a key obstacle that hampers the widespread adoption of AM as a viable manufacturing method. We give an overview of ongoing work deploying tools of in-situ process monitoring, physics-based modeling, and formal uncertainty quantification (UQ) theory to establish process-microstructure-property relationships in metal-based AM and accelerate the Q&C process. The building blocks of our proposed framework and some representative case studies will be highlighted in this presentation, and detailed studies focused on each building block will be given in subsequent presentations.