Current methods for the design of process chains in component manufacturing do not exploit their full potential because material characterizations have typically focused on the impacts made by individual aspects or discrete sub processes. A sequence of sub processes in the process chain can have a cumulative impact on the surface morphology of materials and therefore the fatigue properties of certain batches.

To investigate the effects on material batches of the sequence of sub processes and their parameters, we manufactured specimens with an expansion bolt geometry from four different batches of the steel 42CrMo4. We considered five different process chains, involving heat treatment, turning and grinding sub processes.

We examined the specimens after each sub process by light, optical and scanning electron microscopy (SEM), and fatigue tests.

We found that different sub processes and even sequences of sub processes significantly influenced the surface morphology of the specimens, especially the residual stresses, resulting in high variation of the fatigue properties.