A simplified approach for the simulation based estimation of the phase distribution in a thermo-mechanically treated steel component is presented. A key aspect of the approach is the time-temperature relation for each volume element. Based on a forming simulation with a commercial tool the numerically calculated temperature evolution in the component is analyzed with an in-house code. The code allows estimating the local phase distribution after the forming process with the help of the continuous-cooling-diagram of the material used. A first validation fits well with the existing phase distribution in the component, even though the phase transition in the component is critical in terms of time, deformation and local chemical composition of the material used.

The crack tip field of small fatigue cracks was measured using digital image correlation DIC. For this purpose, smooth specimen were fatigued until a certain amount of damage was visible on the surface. This specimens were then placed in a micro-tensile device in the SEM. The grey value patterns obtained at two different load levels were analyzed with DIC. Fitting the Williams series for the crack tip field to the corresponding DIC-displacement field in the crack tip area yielded the mode-I, and the mode-II stress intensity factors together with the T-stresses. It was found that the experimental values of the stress intensity factor were comparatively high with pronounced mode-II contributions.