Determination of the local constitutive properties of the welded steel joints using digital image correlation method

The digital image correlation (DIC) method has become popular to characterize the local constitutive properties distribution especially for the welded joints. Although the evaluation of the local constitutive properties of a specimen is possible using DIC, few research has been reported to characterize these properties of the welded steel joints. This paper presented a method to evaluate the local constitutive properties of a welded steel joint through tensile testing and DIC method. Firstly, tensile tests of the welded steel joint were carried out and the stress-strain curves of different locations of the welded steel joint were obtained by the DIC method. Then these experimental stress-strain curves were fitted by an appropriate material model. Constitutive properties at these specific locations of the welded steel joint were then determined using this model based on test standards and the Considère criterion. The results showed that the Young's modulus of different sub-regions of the welded steel joints were almost constant. The yield and tensile strength decreased from the weld metal (WM) to the heat affected zone (HAZ) and the base metal (BM). It was also found that the hardening properties of different sub-regions of the welded steel joint followed the sequence of BM > WM > HAZ. This paper contributed a simple method to characterize the local material properties of welded steel joint.