Nav: Home

Detecting damage in non-magnetic steel with the help of magnetism

July 23, 2018

Wear, corrosion, material fatigue are signs of degradation that are common to most materials. This makes it all the more important to detect damage early, preferably on the micrometer scale. Magnetic test methods are often used for this purpose, which was previously impossible with non-magnetic steel. Researchers from Kaiserslautern and Mainz have now developed a process in which they apply a thin magnetic layer to steel. Changes in the microstructure can thus be detected by changes in magnetic effects. Materials such as aluminum can also be tested in this way.The corresponding paper has been published recently in the Journal of Magnetism and Magnetic Materials.

Steel is one of the most frequently used materials. We use it in many variants, for example in the form of stainless steel, high-strength quenched and tempered steel, or low-priced structural steel. Steels can be magnetic or non-magnetic. They are used in cutlery, in automotive components, in steel girders of buildings, and in bridges. At times, steel is exposed to high temperatures and stress. "This can result in microstructural changes, cracks, or component failure," said Dr. Marek Smaga, a researcher at the Department of Materials Science at Technische Universität Kaiserslautern (TUK). This is what experts refer to as material fatigue. Initially, such damage is only visible on the micrometer level. With magnetic testing methods, however, it is not yet possible to detect changes in this scale in non-magnetic steel at an early stage. Engineers from TUK and physicists from Johannes Gutenberg University Mainz (JGU) are working on this problem and are presenting a solution in their current study. The unique feature of their method is that it makes use of magnetic effects, even if the material being tested is non-magnetic.

The Mainz-based researchers coated a non-magnetic steel with different magnetic films, each 20 nanometers thin and composed of terfenol-D, an alloy of the chemical elements terbium, iron, and dysprosium, or of permalloy, a nickel-iron compound. The physicists then used a so-called Kerr microscope to check whether strains of the steel can be detected in the microscopic range. "This is achieved using the so-called Kerr effect, which allows the magnetic microstructures, the so-called domains, to be imaged by rotating the polarization direction of light," explained Dr. Marek Smaga.

The scientists examined magnetically coated steel plates a few millimeters thick that had previously been exposed to mechanical stress. "We observed a characteristic change in the magnetic domain structure," explained Dr. Martin Jourdan from the Institute of Physics at JGU. "Microscopic strain in non-magnetic steel causes the direction of magnetization of the thin layer to change."

Compared to conventional testing procedures, this method has the advantage of detecting signs of fatigue much earlier as it is effective at the micrometer level. The researchers' method could be used in new testing techniques in the future. In addition, the technique is not only interesting for non-magnetic steel. Other materials such as aluminum, titanium, and certain composite materials could also be treated with such a layer.

The project was part of the work undertaken by the Transregional Collaborative Research Center (CRC/TRR) "Spin+X: Spin in its collective environment", which is based at TU Kaiserslautern and Johannes Gutenberg University Mainz and financed by the German Research Foundation (DFG). The CRC/TRR involves interdisciplinary teams of researchers from the fields of chemistry, physics, mechanical engineering, and process engineering, who undertake research into magnetic effects that are to be transferred to application. The primary focus is on the phenomenon of the spin. Physicists use this term to refer to the quantum mechanical momentum of a quantum particle, such as an electron or proton. This forms the basis of many magnetic effects.
-end-
Image:

http://www.uni-mainz.de/bilder_presse/08_physik_werkstoffpruefung_stahl_beschichtungsapparatur.jpg

Dr. Martin Jourdan and Bachelor degree student Moritz Krämer coating non-magnetic steel with various magnetic films, each 20 nanometers thick, using the coating apparatus at JGU's Institute of Physics. photo/©: Martin Jourdan

Publication:

M. Jourdan et al., Strain detection in non-magnetic steel by Kerr-microscopy of magnetic tracer layers, Journal of Magnetism and Magnetic
Materials
465, 143-146, 2018,
DOI:10.1016/j.jmmm.2018.05.081
https://www.sciencedirect.com/science/article/abs/pii/S0304885318306668

Contact:

PD Dr. Martin Jourdan
Institute of Physics
Johannes Gutenberg University Mainz
55099 Mainz, Germany
phone: +49 6131 39-23635
e-mail: jourdan@uni-mainz.de
https://www.klaeui-lab.physik.uni-mainz.de/martin-jourdan/

Dr.-Ing. Marek Smaga

Institute of Materials Science and Engineering
University of Kaiserslautern
67653 Kaiserslautern, Germany
phone: +49 631 205-2762
e-mail: smaga@mv.uni-kl.de
https://www.mv.uni-kl.de/wkk/wkk-lehrstuhl0/wkk-mitarbeiter0/container-schwing/wkk-ma-smaga0/

Related links:

https://www.uni-kl.de/trr173/home/ - Transregional Collaborative Research Center 173 "Spin+X: Spin in its collective environment"

https://www.klaeui-lab.physik.uni-mainz.de/ - Kläui Lab at the JGU Institute of Physics

Read more:

http://www.uni-mainz.de/presse/aktuell/3937_ENG_HTML.php - press release "Antiferromagnets prove their potential for spin-based information technology" (29 Jan. 2018) ;

http://www.uni-mainz.de/presse/18238_ENG_HTML.php - press release "Mainz University opens Spin Phenomena Interdisciplinary Center to accelerate spin research" (22 April 2015)

Johannes Gutenberg Universitaet Mainz

Related Fatigue Articles:

Biomarkers link fatigue in cancer, Parkinson's
Biological markers responsible for extreme exhaustion in patients with cancer have now been linked to fatigue in those with Parkinson's disease, according to new research from Rice University.
Fatigue is a common but underestimated symptom of endometriosis
Two papers published in Human Reproduction journal show that the prevalence of fatigue is more than doubled in women with endometriosis but is underestimated, meaning that doctors should be making greater efforts to discuss and treat this debilitating symptom in these women, and that a history of some types of child abuse is linked to an increased likelihood of endometriosis in adulthood.
New 3-D display takes the eye fatigue out of virtual reality
A new type of 3-D display could solve the long-standing problem eye fatigue when using VR and AR equipment by greatly improving the viewing comfort of these wearable devices.
Chronic fatigue syndrome linked to imbalanced microbiome
Scientists at the Center for Infection and Immunity (CII) at Columbia University's Mailman School of Public Health have discovered abnormal levels of specific gut bacteria related to chronic fatigue syndrome/myalgic encephalomyelitis, or ME/CFS, in patients with and without concurrent irritable bowel syndrome, or IBS.
Conquering metal fatigue
Researchers have found a way to greatly reduce the effects of fatigue in steel by incorporating a laminated nanostructure into the material.
Anakinra does not seem to improve fatigue severity in women with chronic fatigue syndrome
The anti-inflammatory biologic drug anakinra does not seem to reduce fatigue severity in women with chronic fatigue syndrome.
Reducing cancer-related fatigue
A new article published online by JAMA Oncology analyzed which of four commonly recommended treatments -- exercise, psychological, the combination of both, or pharmaceutical -- for cancer-related fatigue appeared to be most effective.
Urine test for fatigue could help prevent accidents
Doctors, pilots, air traffic controllers and bus drivers have at least one thing in common -- if they're exhausted at work, they could be putting lives at risk.
Genetic cause for shift work fatigue discovered
Some people adapt easily to shift work, but not everyone can handle constant disruptions to their daily rhythm.
Management of fatigue and sleep in chronic illness
The College of Nursing at the University of Massachusetts Amherst recently was awarded a five-year, $1.23 million grant from the National Institute of Nursing Research to create a new center where scientists will develop technologies to help people with chronic illness manage fatigue and impaired sleep.
More Fatigue News and Fatigue Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.