Analysis of the functional properties in the bore sub-surface zone during BTA deep-hole drilling

The BTA deep hole drilling process is analysed to determine the relationships between process-structure and residual stress as a function of surface conditioning during the machining process. The residual stresses, the hardness and structural changes in the microstructure are used as indicators for a following process control in order to generate an improved component service life or reliability. In the first tests, the deep-drilled samples are examined with regard to residual stresses, bore tolerances, microstructure and hardness in the sub-surface zone. Furthermore, the specimens will be subjected to a heat treatment to establish a stress-free microstructure as a reference state for the magnetic residual stress measurement.