PNNL-13501 - Pacific Northwest National Laboratory

Study Control Number: PN00062/1469
Joining of Dissimilar Materials for Lightweight Automotive
Richard Davies, Mohammad Khaleel, Darrell Herling, Danny Edwards
The automotive industry is working continually to develop and apply technology that reduces the weight of its product,
thus minimizing the fuel consumption and environmental impact of future vehicles. We are developing materials and
associated technologies for potential use in future automotive applications. The results of this research indicate that the
optimum next generation automobile will likely be a hybrid material structure. A critical enabling technology for the
production of hybrid material vehicles is the joining of dissimilar materials. This project focused specifically on
developing technical capabilites in the area of joining of dissimilar materials for automotive structures.
Project Description
The automotive industry is focused on the overall
reduction of vehicle weight to ultimately reduce fuel
consumption and vehicle emissions. We are developing
materials and associated technologies for potential use in
future automotive applications. The results of this
research indicate that the optimum next generation
automobile will likely be a hybrid material structure. A
critical enabling technology for the production of hybrid
material vehicles is the joining of dissimilar materials.
This work specifically focused on developing technical
capabilites in the area of joining of dissimilar materials
for automotive structures. This project will focus on
friction stir welding to address relevent future material
joint combinations. The work focused on dissimilar cast
and wrought aluminum alloys, aluminum-magnesium,
and metal matrix composites joints. The associated
solutions to these emerging automotive and heavy vehicle
needs will help meet the requirements of the next
generation hybrid material automotive structures.
Introduction
The automotive industry, aerospace industry, and the
United States military have expended a tremendous
amount of effort to investigate and develop new materials
for applications that improve the quality and reduce the
weight and costs of their respective products. Current and
past efforts have developed many substantially different
materials, and have dramatically increased the need for
the joining of unique and dissimilar materials. Many of
these new and dissimilar materials may not be practically
or reliably joined via classical welding and mechanical
fastening methods. Therefore, the ultimate assembly of
future hydrid material transportation and military products
must rely on advanced and substantially more complex
186 FY 2000 Laboratory Directed Research and Development Annual Report
joining methods. This work focused on developing
technical expertise with experimental and modeling
capabilities for joining of dissimilar materials.
The friction stir welding technique developed and
patented by The Welding Institute uses a rotating and
translating mechanical probe that advances through a joint
to create a bond. A schematic of the friction stir welding
process is shown in Figure 1. The friction stir welding
process is a simple process that relies only on the energy
of the rotating welding head to produce the weld. No
additional external power is input into the system and the
heating, stirring, and friction welding of the two materials
creates the bond. Friction stir can be used for joining
many types of materials and material combinations, if tool
materials and designs can be found that operate at the
forging temperature of the work pieces. Most efforts
developing this process have focused on the joining of
aluminum and its alloys. The process has been proven to
weld 2000, 5000, 6000, and 7000 series aluminum alloys
Figure 1. Schematic illustration of the friction stir welding
process