Electric resistance spot welding has been used for
many years in the automotive industry for joining
body sheet components, and it is particularly well
suited for uncoated low carbon steel. Difficulties arise
when applying such spot welding to low resistance
metals, such as aluminum. It is known that resistance spot welding between dissimilar metals, such asbetween a steel and aluminum, often creates an in-
termetallic compound as a result of alloying
between the dissimilar metals. In addition, the formation of the IMC results in deteriorated mechanical properties because the IMC is known to be brittle.
In particular, for a combination of a steel and an
aluminum alloy, an IMC is likely to be formed, and
further, the electrical and thermal properties impose
large restrictions on current conditions, making it
very difficult to obtain sound welding