Fatigue Crack Development in Tensile-Shear Spot Weldments
by
Gary A. Smith
F. V. Lawrence
Department of Metallurgy and Mining Engineering
Abstract
Electrical resistance spot welding has been utilized as a joining process in the automotive industry for many years. A schematic of the spot welding process is shown in Fig. 1. The use of spot welds in automobile manufacturing has increased dramatically in recent years, primarily due to the need to reduce automobile weight and increase fuel efficiency. As a result, thinner guages of high-strength-low-alloy (HSLA) steel have replaced thicker, heavier sections of mild steel in many applications. The weight savings obtainable through the implementation of unit-body construction practices have also been realized. Thus, the electrical resistance spot weld has become the principal joining method in use in the automotive industry today; over 4,000 spot welds are used to create a typical automobile. With the continuing trends toward thinner and lighter sheet thicknesses, there is a critical need for a thorough understanding of the fatigue process in electrical resistance spot welds.
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