Content area
Full text
A tailor welded blank (TWB) consists of two or more flat sheets joined together before forming to provide customized properties in the finished part. Each component is made of a different material, which may differ in grade, gage, strength, or coating; and each material is placed exactly where it is needed. TWBs eliminate the need for the reinforcement components and additional spot welding that traditional designs require.
Steel TWBs have been available for some time, most notably by Cadillac Motor Car Division of General Motors, and the Volvo 850. Their advantages include reduction in cost, scrap, and weight, as well as parts consolidation and improvements in structural integrity and dimensional consistency. For example, the Auto/Steel partnership's ultralight steel autobody (ULSAB) demonstration project involves 18 TWBs - about four times the number in current designs. The objective is to produce an auto with a body mass 25% less than current fourdoor, midsize, conventional vehicles.
However, the cost of producing a TWB is frequently prohibitive and is the most common barrier to implementation. The growth in suppliers and the number of laser-welding systems available have changed the TWB market in recent years. Close to 15 million Laser TWBs were produced for the auto industry in 1997, and the numbers are projected to increase to 40 to 60 million by the year 2000.
The application of TWB technology to aluminum sheet alloys in the production of automotive components is still immature, as it has been only a demonstration technology, but it offers benefits similar to steel TWBs- It helps to reduce the effective cost of aluminum by reducing scrap, consolidating parts, and improving structural rigidity and dimensional tolerances. This article describes the most appropriate aluminum alloys and discusses the most successful welding methods.
Alloy selection
Aluminum alloys considered for tailor welded blanks include mainly the 5000 series for automotive inner body panels, and the 6000 series for outer body panels and general structural components. Specifically, these include 6111-T4, 5754-0, 6061, 5182, 5052, and 5454. Because 6111-T4 and 5754-0 are both weldable and formable, they have been studied the most thoroughly. However, the 5000 series alloys are generally easier to weld; as a result, they look more promising for initial TWB applications as inner components than 6000 series...