WE Colloquium: Dennis Harwig @ 264 MacQuigg Labs
Nov 20 @ 4:00 pm – 5:00 pm

Affiliation: Chief Innovation and Transition Officer – Lightweight Innovations for Tomorrow (LIFT); Adjunct Professor, Welding Engineering

Title: Arc Welding Process Optimization Framework



Arc welding processes are very important to a wide range of industries to manufacture high integrity products and structures.  The process family represents the largest segment of the welding market, over $10 billion annually in equipment and consumable sales.  For gas metal arc welding, there are almost unlimited process combinations.  This includes the selection of consumables – electrode type (hundreds of alloys), diameter, and shielding gas (numerous mixtures of argon, helium CO2, oxygen, etc).; power supply type, polarity, and current waveform (constant voltage, constant current, direct current electrode positive pulsing, variable polarity, etc); process derivatives (twin, tandem, rotating electrode, cold metal transfer (CMT), surface tension transfer (STT), etc).  This presentation will discuss a process optimization framework that can be used to benchmark process potential, develop functional process relationships for process control & optimization, and selection of preferred parameters for welding procedures.  The framework also includes optimizing metal transfer for producing preferred weld pool shape and its effects on stability, spatter, fume, and defect susceptibility.  Future work aims at developing better experimental methods to measure heat input, melting rate properties, bead shape control and techniques to minimize process optimization cost; and extend these development methodologies to other fusion welding process combinations, especially laser, hybrid laser-arc, directed energy metal additive manufacturing.


B.S. Welding Engineering, The Ohio State University, 1985

M.S. Welding Engineering, The Ohio State University, 1988

Ph.D. Welding Engineering Technology, Cranfield University, 2003

Dennis Harwig started his career as a welder in 1978.  He worked 2 years as a Welding & Manufacturing Engineer at General Electric Astrospace Division developing technology for refractory metal nuclear power equipment.  He worked 4 years as a Research Engineer at Babcock & Wilcox Alliance Research Center and was a principal inventor of the patented shape welding process.  He was promoted to Lead Welding Engineer & Program Manager and worked for 2 years at Babcock & Wilcox  Nuclear Equipment Division on Navy nuclear propulsion equipment.  Dennis joined EWI in 1994 and over 10 years served as Principal Engineer, Team Manager (Arc Welding and Automation), Cooperative Research Program Manager, and Technology Leader in Arc Welding, Materials, and Automation.  In 2004, he joined Thermadyne Industries’ Brand Management Division as Director of Global Engineering.  Shortly after, Dennis became Vice President of Global Engineering and Vice President of Global Quality at Thermadyne.  He rejoined EWI in 2008, and served as Business Development Director (2008-2011), Navy Joining Center Director (2010-2013), and Center Development Director (2011-2013).  In January 2014, Dennis joined the  American Welding Society as Chief Technology Officer where he led three departments; Technical Services, Education Development, and Education Operations whose combined operating revenue was over $13M.  In December 2015, Dr. Harwig joined The Ohio State University and Lift as Chief Innovation & Transition Officer.  In this dual appointment role, Dennis leads business development and commercialization opportunities to drive sustainability of LIFT.

Dennis has published more than 110 presentations, proceedings, journal articles, and EWI Core Research Reports; recently served on nine AWS committees and three IIW committees; and developed eight patents.

WE Colloquium: Michael Groeber @ 111 EJTC
Dec 4 @ 3:00 pm – 4:00 pm

Affiliation: Senior Materials Research Scientist, Metals Branch/Materials State Awareness Branch Air Force Research Lab, WPAFB

Title:Combining characterization, modeling, and analytics toward understanding and manipulating process-structure linkages in metallic 3D printing



Additive manufacturing (AM) presents both extreme potential and concern for component design.  In addition to the complicated geometries that AM enables, the ability to locally tailor processing path opens the door to sophisticated new designs with heterogeneous properties.  However, accounting for this heterogeneity, before exploiting it, requires the ability to link local processing state to properties/performance of local material.  A concern with current geometry-based design approaches, such as topology optimization, is not directly accounting for material property changes as geometry updates are made.  Given current closed and fixed scanning strategies of most commercial systems, local processing paths are potentially altered significantly with seemingly minor macroscopic geometry changes and are unable to be avoided.

This talk will present methods for combining process monitoring, thermal modelling and microstructure characterization to mechanistically explain process-to-structure relationships in metal additive manufacturing.  The talk will discuss heterogeneities in the local processing conditions within additively manufactured components and how they affect the resulting material structure.  Methods for registering a fusing disparate data sources will be presented and the utility of different data sources for specific microstructural features of interest will be discussed.  It is the intent that this talk will highlight the need for improved understanding of metallic additive manufacturing processes and show that combining experimental data with modelling and advanced data processing and analytics methods will accelerate that understanding, ultimately driving optimization routines for process control.

Additionally, this talk will outline building ICME modules that predict microstructure (grain size, texture, void Vf, etc.) from processing history and predict performance (E, σys, hardening rate, εf, etc.) from microstructure.  These modules will be designed to interface with topology optimization codes to dynamically account for material properties as geometry updates are made.  The work is being demonstrated using a laser-based powder-bed fusion process on nickel superalloy IN625 for thin-walled structures.  Highly-pedigreed data sets of in-situ monitoring data (beam path, thermal measurements), post-build characterization (CT, RUS, 3D Optical and SEM) and mechanical testing (milli-tensile, HEDM, notch and torsion testing) will be collected and provided to the open community.  Challenges problems will be commissioned to benchmark the current modeling capabilities in process-structure and structure-properties.  Finally, challenge results will be used in novel forecasting techniques akin to weather forecasting strategies of model aggregation.  This talk will present the current state of the program and the vision for community involvement.



Michael Groeber is currently a Senior Material Research Scientist in the Metals Branch of the Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio.  Dr. Groeber’s research projects focus on the quantification and representation of microstructure for improving process and property modeling, in addition to structure and process optimization for additive manufacturing.  Dr. Groeber is the originator/inventor and one of the principal developers of DREAM.3D, a unique software package that integrates several digital microstructure tools that will facilitate the advancement of Integrated Computational Material Science and Engineering (ICMSE) in the Air Force and outside.  Additionally, Dr. Groeber has worked on creating autonomous, multi-modal data collection systems that integrate real-time analysis to optimize microstructure data collection and analysis.  Recently, Dr. Groeber has focused on applying these developments to advancing the understanding of additive manufacturing.  Dr. Groeber received a Bachelor’s of Science degree in Materials Science and Engineering from the Ohio State University in 2003, followed by a Ph.D. from the Ohio State University in 2007.  Dr. Groeber has published over 30 peer reviewed journals, 3 book chapters and presented over 20 invited international presentations.