Staff Members:

Past Staff Members:

  • S. S. Babu
  • J. W. Cohron
  • J. W. Park
  • S. M. Kelly
  • J. F. King
Mission:

To advance the science and technology of materials joining by developing welding and brazing procedures for a variety of materials and by studying the fundamentals of joining processes and their effects on the microstructure and properties of materials and to develop advanced techniques and associated equipment to examine and evaluate metals, ceramics, composites, films and other materials nondestructively.

Expertise: State-of-the-Art:

The group's projects range from the fundamental aspects of welding, including modeling of processes to applied technology. Members of the staff are world renowned for their contributions to technology and have been recognized by numerous awards from the AWS, ASM International, TMS, ASME, and AAAS. Members of the staff also have served on the Industrial Advisory Board of the Edison Welding Institute and hold adjunct professorships at several universities. Over the years the members of the group have contributed to over 900 technical papers.

  • Fundamental understanding of heat source - material interactions including heat and mass transport
  • Modeling of weld pool, distribution and residual stresses
  • Fundamentals of weld pool solidification and solid state phase transformations in weldments
  • Residual stress measurement and characterization in weldments and braze joints
  • Weldability testing and characterization, welding of austenitic stainless steel and superalloy single crystals
  • Process development, specification, and filler metal development and joining of steels (austenitic and ferrite alloys), low alloy steels, aluminum alloys, superalloys and ductile intermetallic alloys
  • Friction stir welding of aluminum, steel titanium and nickel base superalloys
  • Brazing of metals, ceramics, and ceramics to metals, braze alloy development


Facilities: State-of-the-Art:

A broad technical support to characterize weldments such as fracture mechanics, analytical electron microscopy, nondestructive examination, mechanical properties, and unique neutron scattering facilities to measure residual stresses exists.

  • A wide range of joining processes including arc, friction stir welding, arc-laser hybrid process, electroslag and electrogas welding and high energy beam processes such as electron beam, and laser welding and brazing.
  • Weldability testing of materials
  • Brazing facilities to join metals and ceramics, including vacuum and controlled atmosphere furnaces
  • Computational thermo dynamic and kinetic models
  • Neural net modeling for microstructure and properties
  • Facilities to characterize braze alloy wetting characteristics
  • A vision system to view weld pool dynamics
  • Materials characterization facilities including optical microscopy, advanced analytical electron microscopy, surface characterization facilities, x-ray and neutron scattering facilities, computed tomography, ultrasonic microscopy and eddy-currents

Examples of Relevant Work:

ORNL has been the lead Lab for DOE Basic Energy Sciences Welding Science Program and other applied programs.

  • Nondestructive testing of structural ceramics for Ceramic Technology for Advanced Heat Engines
  • BES Welding Science Program
  • Welding development for Fossil Energy Materials Program
  • Welding and brazing development for Advanced Industrial Concepts and Ceramic Technology Programs
  • Weldability studies for Space Nuclear Power and Magnetic Fusion Energy projects
  • Advanced eddy-current probes & analysis programs for USNRC inspection of nuclear steam generators


Past Work Includes:

  • Understanding the relationships among processes, microstructure, physical and mechanical properties,
  • leading to the development of a unique, fast-transient 3D-mathematical modeling and experimental
  • verification capability to address transport in welds and their influence on weld microstructures.
  • Understanding the evolution of the weld metal microstructures during welding and subsequent elevated
  • temperature exposure in support of welding single-crystal turbine blades and repair welding of
  • single-crystal turbine components.
  • Developing extensive expertise for brazing ceramics to related and non-related materials using special
  • braze filler materials and metallizing to overcome wetting problems.
  • Understanding solidification behavior and weld-cracking mechanisms in nickel aluminide alloys to guide
  • development of new alloys resistant to weld solification cracking.
  • Supporting development of RF antennas for plasma heating by providing guidance for material selection
  • and conducting the joining procedure development for similar and dissimilar materials combinations.
  • Routinely performing hot-cracking resistance tests on iridium alloy fuel cladding used in the space nuclear
  • program as a part of flight qualification for NASA missions.


Unique Capabilities:

ORNL's experience and capabilities in advancing the science and technology of materials joining and their applications to various technologies are unparalleled in the U.S. and are nationally and internationally recognized.

  • Standard welding processes, including gas tungsten arc (GTA), submerged arc (SA), gas metal arc
  • (GMA), and electroslag (ES)
  • Pulsed and high power continuous wave CO2 laser systems
  • High power electron beam welding machine
  • Internal bore tube-to-tube sheet welding system
  • Narrow gap SA welding system
  • Gleeble thermomechanical simulator
  • Sigmajig and varestraint weldability testing capability
  • Variable polarity plasma arc system
  • Weld vision system for weld pool dynamic studies
  • Interrupted and controlled solidification high-temperature furnace
  • Sessile drop apparatus for brazing alloy wetting studies
  • Ceramic-to-ceramic and ceramic-to-metal brazing capabilities
  • State-of-the-art friction stir welding and processing equipment
  • Ultrasonic welding


Research Programs:

  • Fundamentals of Welding and Joining
  • Application of Synchroton and Neutron Sources for In-situ Phase Transformation Study
  • Nickel Aluminide Program - OIT
  • New Generation Turbine Single Crystal Program - Fossil Energy
  • Virtual Welded Joint Design - Catepillar Corporation - OIT (IMF Program)
  • Optimization of welding consumables - Lincoln Electric - OIT (Supporting Industries Program)
  • Wear Resistance Coatings through Laser Surface Alloying - Applied Research Laboratory - OIT (IMF Program)
  • Development of Fe-3Cr heat resistant steels - OIT (IMF Program)
  • Friction Stir Processing - OTT
  • Long Life Electrode Project - OTT
  • Space Power Program
  • MPLUS User Program

Completed Research Programs:

  • PNGV - Welding Science for New Generation Vehicles
  • LDRD - SOL Laser Assisted Arc Welding Project


Collaboration:

  • University of Cambridge, Cambridge, UT
  • Graz University of Technology, Austria
  • The Pennsylvania State University, State College, USA
  • Colorado School of Mines, Golden, Colorado, USA
  • Lincoln Electric Company, Cleveland, USA
  • Westinghouse Electric Corporation, USA
  • Caterpillar Corporation, USA
  • Ford Motor Company, USA
  • Lawrence Livermore National Laboratory, USA
  • Applied Research Laboratory, State College, PA
  • Engineering Mechanics Corporation of Columbus, OH



Relevant Publications:

  • S. A. David, S. S. Babu, and J. M. Vitek, “Overview – Welding: Solidification and Microstructure,” JOM-J MIN MET MAT, 2003, 55, 14-20.
  • M. L. Santella, et al. 2003. "In-Situ Characterization of Austenite to Martensite Decomposition in 9Cr-1Mo-V Steel Welds," Proc. Austenite Formation & Decomposition Symposium, Chicago, IL USA, TMS, TMS, Chicago, IL USA, 11/09/2003-11/12/2003.
  • S.A. David and Z. Feng, “Friction Stir Welding of Advanced Materials: Challenges,” IIW Materials Conference, Graz, Austria, IIW, 11/19/2004 – 11/20/2004.
  • Z. Feng, X-L. Wang, S.A. David, and P.S. Sklad, “Modeling of Residual Stresses and Property Distributions in Friction Stir Welds of Aluminum Alloy 6061-T6,” 5th Intl Symp Friction Stir Welding, Metz, France, TWR, 9/14/2004-09/16/2004.
  • O. M. Barabash, J. A. Horton, S. S. Babu, J. M. Vitek, S. A. David, J-W. Park, G. E. Ice, R. I. Barabash, “Evolution of Dislocation Structure in the HAZ of a Nickel-Based Single Crystal," J. Appl. Phys, 96, Issue I & 7, 3673-3679, 2004.
  • Z. Feng, et al. 2004. "Prediction of Residual Stresses and Property Distributions in Friction Stir Welds of Aluminum Alloy 6061-T6," Proc. 5th Int'l Symposium of FSW, Metz, France, TWI, 09/14/2004-9/16/2004.
  • M.L. Santella, T. Engstrom, D. Storjohann, T-Y. Pan, A.R. Krause, and F. A. Conle, “Effects of Friction Stir Processing on Mechanical Properties on the Cast Aluminum Alloys A319 and A356,” Scr. Materialia. 2004.
  • D. Lee, M.L. Santella, G.M. Pharr, and I.M. Anderson, “Thermal Aging Effects on the Microstructure and Short-Term Oxidation Behavior of a Cast Ni3Al Alloy,” Intermetallics, 2004.
  • D. Storjohann, O. M. Barabash, S. S. Babu, S. A. David, P. S. Sklad, and E. E. Bloom, “Fusion and Friction Stir Welding of Aluminum Metal Matrix Composites,” Metal. Mater. Trans. A. 36A, 3237 - 3247 (2005).
  • G.M.D. Cantin, S. A. David, W. M. Thomas, E. Lara-Curzio, and S. S. Babu, "Friction Skew-Stir Welding of Lap Joints in 5083-0 Aluminium,” Sci. Technol. Weld. Joining, 10, (3), 268 - 280 (2005).
  • M.L. Santella, T. Engstrom, D. Storjohann, and T-Y. Pan, “Effects of Friction Stir Processin on Mechanical Properties of the Cast Aluminum Alloys A356,” Society of Automotive Engineers Trans. 2005.
  • O.M. Barabash, J.A. Horton, S.S. Babu, J.M. Vitek, S.A. David, G.E. Ice, and R.I. Barabash, “Multiscale Characterization of Deformation Mechanisms in the Weld Joint of a Nickel-based Superalloy,” Mater. Res.Soc. Symp. Proc. 882E, EE4.11.1 - EE4.11.6, 2005.
  • W. Woo, H. Choo, D.W. Brown, Z. Feng, S.A. David, C.R. Hubbard, and M.A.M. Bourke, “De-convoluting the Influences of Heat and Plastic Deformation on Internal Strains Generated by Friction Stir Processing,” Appl. Phys. Lett. 86, 231092, 2005.

ORNL Contact:

S. A. David, Tel. 865-574-4802; Fax. 865-574-4928; davidsa1@ornl.gov