Microstructure and mechanical properties of DC05 joints obtained by laser welding

The laser welding joint has marked influence on the formability of similar tailor welded blanks. Mechanical properties of these joint are the key parameters to evaluate the formability of similar tailor welded blanks and establish the finite element models. To determine the mechanical properties of laser welds,true stress-strain curve of laser weld was analyzed base on rule of mixture in addition to the utilization of microstructure approach and Digital Image Correlation (DIC). DIC was utilized to determine full-field strain during uniaxial tensile tests and local strains were derived from the strain field and were used to calculate the stress-strain curve. It is shown that the analysis curve is agreed well with the experimental curve of small specimen within the stable deformation stage. However,there are very great differences in the necking behavior,which is probably due to the constraint effect of base material adjacent to the joint. As a result, necking behavior of laser weld is hindered. The strain ratio of laser weld was approximately -0.63,which was deviate from the status of uniaxial tension in which the strain ratio is -0.5. Analytic curve is the true stress-strain curve of laser welds.