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Tech of APT Webinar #9: Investigation of hydrogen embrittlement in high Mn TWIP steel via correlative microscopy (ECCI and APT)

Friday, May 28, 2021

Technology of APT #9: Investigation of hydrogen embrittlement in high Mn TWIP steel via correlative microscopy (ECCI and APT)

The hydrogen embrittlement susceptibility of high-Mn Twinning Induced Plasticity (TWIP) steels requires a nanoscale description which can only be supplied by atom probe tomography. A recent study postulated that hydrogen segregation at stacking faults and random high angle grain boundaries in the studied TWIP steel leads to its hydrogen embrittlement [1]. To examine this, we needed methods to directly charge APT specimens with hydrogen/deuterium. These samples would be prepared by site-specific lift-outs containing a certain specific microstructural feature, such as a grain boundary or stacking faults.

We have explored two different charging routes for charging APT specimens with hydrogen/deuterium: cathodic charging and gas charging. The latter was done using the “Reacthub Module” (RHM) arising from an MPIE/Cameca collaboration, and we will briefly why it came to be, considering the broad experimental space enabled by this device.

Both these hydrogen charging methods have their own merits and drawbacks. During this talk, I will showcase results from both the charging methods, describe in detail the different setups and discuss the merits of the different approaches. Finally, I demonstrate that gas charging using RHM leads to the cleanest results, yet with a slower ingress kinetics.

Guest Speakers:

Heena Khanchandani joined MPIE in April 2019 as a PhD student in the “Atom Probe Tomography”group of Dr. Baptiste Gault and “Microscopy and Diffraction” group of Dr. Stefan Zaefferer, funded by the ERC-SHINE project. She did her masters in Materials Science through Erasmus Mundus MaMaSELF programme, thereby receiving joint Masters degree from two institutions: University of Montpellier, France and Ludwig Maximilians University Munich, Germany. Currently, she is working on investigation of hydrogen embrittlement in high Mn Twinning Induced Plasticity steels.

Dr. Leigh Stephenson has been leading projects at MPIE in Dr. Baptiste Gault’s group since 2017,notably as concern the preparation and treatment of environmentally-sensitive APT specimens under the auspices of the Laplace Project and Dr. Gault’s SHINE ERC project.

At MPIE, his main concern wasto develop these new experimental methods and devise sustainable protocols for the use andmaintenance of the emerging suite of instruments integrated together by vacuum-carry transfersuitcases.

Tuesday, June 8, 9AM CST.

Register here.

1. An D, Krieger W, Zaefferer S. Unravelling the effect of hydrogen on microstructure evolution under low-cycle fatigue in a high-manganese austenitic TWIP steel. Int J Plast 2019.