The demand for ultra-high strength steel (UHSS) increased in the last decade due to their favourable properties in the process of press hardening. Press hardening is a process where an austenitized blank of boron steel is formed and quenched in one production step to achieve superior mechanical properties compared to the blank in as-delivered condition. Driving force for the development of this technique is the automotive industry and regulations concerning passenger safety and fuel consumption. In this work fracture in spot welds and their proximity in low alloyed boron steel have been investigated using finite element simulation and digital speckle photography. This study is motivated by the use of spot welding as major joining method in automotive components. The investigation includes blanks with three different base microstructures, ferritic, bainitic and martensitic. These types of microstructures are commonly found in press hardened components with tailored material properties. All test samples are spot welded in a centred position with a coupon. The welding process introduces heat into the blank and affects the microstructure in the vicinity of the weld leading to varying mechanical properties. During tensile testing of the spot welded samples the mechanical response of the material has been recorded by digital speckle photography (DSP), extensometer and force measurement. The experimental method of DSP measurement allows to resolve displacement and strain fields in the specimen up until fracture. For finite element analysis the commercial available code LS-Dyna together with a user defined material model is used. The material model predicts the mechanical response of the bulk material, i.e. the composite, depending on the phase volume fractions of present phases.