Environmental Durability of Epoxy Adhesive/Galvanized Steel Tensile Shear Joints

The adhesive bonding performance of automotive-type galvanized sheet steels was investigated using several epoxy adhesive/surface lubricant combinations. Environmental durability was assessed through exposure to cyclic accelerated corrosion tests.

Results revealed that for both ambient and environmentally exposed samples, both strength and failure mode performance were strongly dependent upon the specific adherend/adhesive combination. Environmentally induced strength degradation in joints of uncoated and zinc coated steels was attributed to corrosion at the adherend/ adhesive interface. The reason for strength losses in zinc-iron coated steel joints was apparently different, and is not clear at this time.

Implications are that for optimum environmental durability, adherends, adhesives and lubricants should be selected using a systems approach.