In the InSitueLUSLine project, a novel concept for the contactless in-situ measurement of anisotropy in steel during thermal treatment is being investigated and verified. The aim is to detect changes in the material structure during the heating process.

For this purpose, a sheet metal sample is inductively heated under vacuum conditions to temperatures between 400 and 800 °C. In this temperature range, metallurgical processes take place that can lead to changes in the material’s anisotropic rolling texture. These changes are monitored throughout the heat treatment using laser-ultrasound.

A special feature of the new measurement approach is a rotating, line-shaped laser excitation, which allows ultrasonic waves to be generated and analysed from different directions within the material. The measurement data obtained are used to continuously determine how the anisotropy changes over time.

The project provides the basis for a new method to investigate structural changes in steel at high temperatures contactlessly and directly during the process. In the long term, this approach could help to better understand, monitor and specifically optimise thermal treatment processes.