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Book Review: Aluminum 2001: Proceedings of the TMS 2001 Annual Meeting Aluminum Automotive and Joining Symposia
07-29-02
Publisher: TMS
The Aluminum Association jointly sponsored (with the Aluminum Committee of the TMS Light Metals Division) a series of sessions at the February 2001 TMS Annual Meeting on topics of relevance to the use of aluminum in automotive applications as well as aluminum joining technologies. Key papers from those sessions have been collected into a recently published Proceedings volume entitled Aluminum 2001: Proceedings of the TMS 2001 Annual Meeting Aluminum Automotive and Joining Symposia. The information in this volume is of both a broad general nature that will be helpful for those looking for an overview of selected areas and a specific nature, addressing new research results in the area of formability and joining.
This collaboration between TMS and The Aluminum Association is a further extension of the role that TMS has assumed as one of the leading professional societies in the aluminum materials and processes field. The topics covered extend beyond the primary processes focus of other TMS publications such as the Light Metals series and address more downstream processing issues. Specifically, the majority of the papers in this volume are in the areas of formability of aluminum sheet and joining of aluminum, including both fusion processes as well as friction stir welding, with a focus on automotive applications.
The formability of aluminum sheet for automotive applications is of continued technical as well as commercial interest. Increasing the formability while maintaining the strengths of the alloy after paint baking is a balance that must be struck constantly. As a result, a number of auto body sheet alloys, both heat treatable and non-heat treatable, have been developed and commercialized in an attempt to meet specific sets of application needs. Six of the papers address aspects of the composition-microstructure-process-property relationship from a fairly scientific basis. Authors are from university, material supplier, and end user organizations. Papers addressing fracture mechanisms during stretch forming as well as bending are included, and the effects of compositional variations of Fe and Cu in 6xxx alloys are reviewed. What is clear from these papers is that the details of composition, processing, and the resulting microstructure are very important in determining formability, especially in severe deformation situations such as the bending that the material undergoes in the body panel hemming process. Another aspect of formability that is addressed is the formation of slivers in the shearing process, and a study of the effect of various punch and die parameters on sliver formation is covered in one paper.
Another key process in the utilization of aluminum alloys for automotive applications is joining. The papers in this Proceedings volume can be roughly divided into two groups; one on fusion processes and the second on the solid-state process of friction stir welding. The fusion joining papers offer a wide range, from a very basic paper on filler alloy selection for aluminum welding to detailed studies of the microstructures of both arc welded and resistance spot welded materials reported in two other papers. Two papers deserve special mention. The first, by Harris of the Edison Welding Institute, provides a good overview of the range of arc welding processes of interest for implementation in auto structures, and emphasizes processes based on gas metal arc and plasma arc welding. In addition to discussion of the welding of automotive structures, there is discussion of the selection of arc welding processes for producing aluminum tubes for subsequent hydroforming. Second is an excellent paper on the use of laser welding for the production of tailor welded aluminum forming blanks from Clarke and Christy from Alcan, which covers the benefits and key process issues with using lasers to join aluminum, and then goes on to describe how this process is deal for the production of tailor welded blanks from similar or dissimilar aluminum alloys.
Friction stir welding (FSW) is a solid state joining process that has attracted considerable attention in the aluminum industry due to its ability to produce high strength joints in alloys typically considered unweldable. Initially focused on aerospace applications, there is interest in this process in the automotive and other markets as well. Two introductory papers provide an overview of these applications. Smith, et al. from Tower Automotive describe the implementation of FSW in automotive applications, including the joining of extrusions, general assembly, and production of tailor welded blanks. They note that one of the main limitations to the use of FSW in the automotive environment, slow travel speed, has been overcome. Also important is the design and programming of the machines to perform the joining process, specifically their ability to compensate for variations in incoming material dimension variations. Another market in which FSW is being employed is in shipbuilding, with the development of high-speed vessels driving increased interest. The ability to use thin walled extrusions that are subsequently joined to replace larger, heavier, more costly extrusions is described in the paper by Collins of High Tech Welding. He notes that FSW for ship applications has now been approved by most, if not all, marine classification societies. Six other papers on various aspects related to friction stir welding are provided, including discussions of the use of the process on welding dissimilar materials and also 7050 aerospace alloy, modeling, and tool development.
A number of other papers that cover topics other than formability and joining are in the Proceedings, and provide in their own right for some very useful reading.
- Two papers, one by Kissell and Malloy and the second by Menzmer, et al., address issues related to the utilization of aluminum in structural applications. While addressing this topic from somewhat different perspectives, the conclusion from both is that the current standards are more conservative than necessary and as a result aluminum can suffer when compared to competitive materials such as steel for structural applications.
- The paper of Gesing, et al. from Huron Valley Steel Corp. discusses the separation of wrought from cast aluminum scrap in automotive recycling, a topic of significant interest in the future as the content of wrought aluminum in automobiles increases and these vehicles are ready to be recycled.
- A low cost aluminum metal matrix composite production process is discussed in the paper of Herling, et al. This process may finally open up larger scale applications of these materials due to the reduced raw material cost.
- Roll cast 5xxx series alloys for automotive application are reviewed by Birol, et al.
The Proceedings volume is available from The Minerals, Metals, and Materials Society (TMS), online at www.tms.org.
Article provided courtesy of The Aluminum Association - www.aluminum.org
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