Evaluation of Constitutive Behavior of Aluminum Extrusions and Their GMAW Welds (2013-01-0384)

Facing the challenge of lightweighting and energy consumption efficiency, aluminum extrusions (e.g. AA6060- T6 and AA6082-T6) may be used to replace steel for bumpers and other crash management systems (CMS). Robotic gas metal arc welding (GMAW) is currently used to weld the beam and bumper box. In order to better understand the crashworthiness of the beam, there is significant interest to obtain constitutive behavior of heat affected zone (HAZ) and weld metal.A new test procedure has been developed to couple both tensile test and shear test with the digital image correlation method to directly measure constitutive behavior of different regions in GMAW welds, namely base metal, HAZ and weld metal. The test procedure has been applied to welds of AA6060-T6 and AA6082-T6 extrusions made using conventional robotic GMAW. The results show that both AA6060-T5 and AA6082-T5 extrusions have undermatched weld metals, while in AA6082-T5 welds, the yield strength of the weld metal was even lower than the heat affected zone. Significant decreases in yield strength in HAZ in both AA6060-T5 and AA6082-T5 extrsuions were observed.