STRESS-SPEC

Fig. 1: STRESS-SPEC at FRM II

Helmholtz-Zentrum Hereon contribute with their texture competence to the operation of STRESS-SPEC at the FRM II together with TUM. STRESS-SPEC is unique in its capability for strain and texture measurements with high local resolution on large volume samples and components.

The determination of the local variation of texture for example by inhomogeneous deformation is very important, due to the coherence between the texture and the physical and mechanical properties of materials. Therefore, a new measurement technique for local texture analyses with neutron radiation was developed.

First measurements of local texture [1-2] have shown that the established method of strain measurement with neutron radiation at STRESS-SPEC [3-4] also provides a good basis for local texture analysis. Due to the flexible configuration it is possible to reduce the data acquisition time for every local pole figure down to 5 hours.

Fig 2: Local texture analysis of a heavy Cu tube (~12 kg) with the robot system

Funded by the BMBF Verbundforschung project, the existing Eulerian cradle, which is limited in sample size and translation, has been replaced by a more flexible robotic system (Fig. 1). The robot can be used simultaneously for automatic sample manipulation and sample change. It allows faster alignment and positioning of larger samples (Fig. 2). In addition, the robot system offers a combined measurement of local texture and strain mapping, and as well more flexibilities for texture analysis under different environments (e.g. electic field).

To improve the current absolute positioning accuracy of the robot, the existing laser tracker system will be implemented, which involves the development of new laser reflection units for general usage. With the success of this laser tracker implementation, the robot can be provided as a standard setup either as at present for bulk and local texture analyses or in the future for strain scanning of conventional and complex samples.

Furthermore, with the installation of event mode based readout of the detector, the data acquisition would be state of the art. It would benefit the texture measurements as they could be done in a continuous scanning mode as well as in-situ experiments like phase transformation kinetics and similar experiment as using the planned dilatometer.