Researchers from Tampere University test Xstress DR45 for small spot size residual stress measurements

Stresstech co-operates with universities and research institutes by developing studies with the research community and collecting information on how to further improve products for the industry.

In December 2022, we invited researchers Suvi Santa-aho and Tapio Jokinen from Tampere University to test our Xstress DR45 X-ray diffractometer for residual stress measurement on a part with challenging dimensions. The part required the use of a very small measurement spot size. After the measurements we asked them to answer a few questions.

Suvi Santa-aho and Tapio Jokinen with Xstress Profile
Suvi Santa-aho and Tapio Jokinen from Tampere University.

Would you give an overview of your faculty at Tampere University?

Tampere University of Technology and earlier University of Tampere merged in 2019 to new Tampere University. Our background is from Tampere University of Technology and now we are at the Faculty of Engineering and Natural Science, in Materials Science and Environmental Engineering unit. Our research group mainly deals with different kinds of material characterization where the non-destructive measurements also belong.

What is your role?

I am working as a Senior research fellow at Materials Characterization group supervised by Professor Minnamari Vippola. My work consists of different kinds of project’s that are in the field of materials characterization and NDT. In addition, I am teaching in some of our courses dealing with materials science and supervising B.Sc., M.Sc., and D.Sc. works. At the moment, the projects are dealing with Barkhausen noise phenomena itself, machining and evaluation of surface layer properties with Barkhausen noise and other material characterization methods. For example, we are inspecting the origin of the Barkhausen noise signal with transmission electron microscopy (TEM) based imaging system. With the TEM, we can take pictures and record video frames of magnetic domains and inspect the interaction of microstructural details and moving domain walls.

Would you describe what kind of measurements you made at Stresstech measurement laboratory?

I came today to visit Stresstech with our M.Sc. worker Tapio Jokinen. Tapio has just started his M.Sc. work that combines the surface machining processes and material characterization with many different tools such as optical microscopy, electron microscopy, optical profilometry and residual stress measurements. The samples that we measured today were machined surfaces of metal components that Tapio has in his M.Sc. work. We have an earlier model of Xstress G2R residual stress measurement device at our laboratory, but the geometry of the samples was such that we could not utilize our own device for these measurements.

Suvi Santa-aho and Tapio Jokinen testing Xstress Profile
Sample positioning with Xstress XY.

What are common difficulties with this kind of measurements?

The area of interest was so small that it required special small collimator tip. The smaller the tip, the longer the exposure time is required for good intensity. We didn’t have as small and custom-made collimator tip at Tampere to carry out the measurements with our own device. In addition, with our device the measurement time with such small collimator tip might have been long. The DR45 measurements were fast even with the small collimator tip.

What kind of results did you get?

We were really grateful that the measurements succeeded. The small custom-made collimator tip worked well and adapted precisely to the small details that we wanted to measure. The measurement results were interesting, and these provide a lot of research output to the M.Sc. work results and help us to evaluate the machining parameters much better.

How would you evaluate the performance of Xstress DR45?

I saw the operation of the XStress DR45 for the first time on the spot. Compared to the old device that I have experienced; the measurement was really fast. The measurement software (Xstress Studio) was new and a bit different than the old XTronic software, but it was easy to learn how to use. We got training for the software and after a while we could easily run the measurements ourselves. The results were collected as one single pdf-file where we could take the relevant results and interpret them. I find the operation of the DR45 really efficient; with decreased measurement time much more samples could be analyzed compared to the old device.

Article Type: Interview
Technology: X-ray diffraction
Product Line: Xstress DR45