Expertise - Materials Joining Group

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

Research & Development

Capability
Arc, resistance, laser, laser assisted arc, electron beam, friction and robot welding, and brazing processes

Tools
Thermomechanical simulator, weldability testing, weld vision-systems and residual stress mapping
Characterization
Advanced characterization including analytical electron microscopy, atom probe tomography, synchrotron and neutron diffraction

Modeling
Computational thermodynamic and kinetic models, property models, microstructure models, artificial neural network models and integrated weld process models

Capabilities span a wide range of applied research programs:

Energy Research
Space Power
Aerospace
Automotive


Laser Assisted Arc		Arc Welding

		Brazing
Resistance Spot Welding		Prototype ceramic-metal engine valve

Fundamentals of materials joining are being investigated to develop a science base:

Nonequilibrium solidification in welds
Microstructure evolution
Phase stability & kinetics
Properties
Welding consumables
Residual stresses


	Nickel base single crystal welds are being studied using solidification theories


	Liquid-Oxide thermodynamic equilibria describe inclusion formation in welds


	Nonequilibrium y´ precipitates in rapidly cooled nickel base superalloy are characterized using atom probe tomography.

Advanced computational and analysis techniques are being used to develop optimum materials joining solutions:


		Synchrotron diffraction is used to monitor nonequilibrium phase transformations


		Thermodynamic and kinetic modeling predict phase stability in welds


		Artificial neural network model describes weld pool shapes


		Gleeble® thermomechanical simulations track solid-state phase transformations