Study on Elastoplastic Crack Propagation Behavior of Laser-welded 6061 Aluminum Alloy Using Digital Image Correlation Method

Laser welding is commonly used in the aluminum alloy welding of aerospace field as an efficient and precision welding method. Local high temperature and electrode material change the microstructure of aluminum alloy in the laser welding process. The nonuniform and weakened material properties in the weld zone will result in localized stress concentration, which induced the plastic deformation and the crack initiation of the weld. In this paper, the digital image correlation method was used to study the elastoplastic crack propagation of laser welding 6061 aluminum alloy. According to the method that determines the nominal crack-tip of the weld, we obtained the CTOA and CTOD. The experimental results showed that CTOA, CTOD and J-integral increased nonlinearly with the crack propagation in the heat affected zone.