Determination of the constitutive behaviour of AA6022-T4 aluminium alloy spot welds at large strains

There is increasing demand within the automotive industry to utilize aluminium alloy sheets and their spot welds to facilitate vehicle weight reduction and increase fuel economy. While traditional uniaxial tensile testing only determines mechanical properties to small strains, direct measurement of the constitutive behaviour of aluminium alloy spot welds to large strains remains a challenge. For the first time, the present work employed digital image correlation coupled with shear testing to directly measure the constitutive behaviour of an AA6022-T4 spot weld to large strains. The results show that the spot welding process not only decreases the yield strength but also lowers the work hardening rate of the nugget versus the base material. The paint bake cycle partially recovers the yield and shear strength of the nugget.