Response of Aluminum Alloys to Temperature Exposures Observed in Automotive Service

This report presents results of experiments to determine the effect of elevated temperature exposures on the mechanical properties of aluminum alloy materials. The two alloys studied, 5754 and 6111, are of the types which would be used in a stamped automobile structure and exterior panels. Yield strength, tensile strength, and total elongation are reported for a variety of test conditions. The material temperature exposures simulated a broad range of conditions which might be experienced during manufacturing operations such as adhesive curing and vehicle paint bake cycles. In addition, tests were conducted at temperatures to resemble in-service under-hood and under body (near the exhaust system) conditions. Materials were prestrained various amounts prior to temperature exposure to simulate metal forming processes. Results show that both materials react to temperature and aging times differently. Alloy 5754 maintains stable mechanical properties while alloy 6111 increases in strength except at the long exposures and high temperature levels. With both materials mechanical properties decrease at the higher temperatures.