Evaluation of Residual Stresses by Microscale FIB-DIC Ring-Core Milling and Other Techniques for Beam Dump Application at CERN
Author
Fagnoni, Francesco
Term
4. semester
Education
Publication year
2019
Submitted on
2019-06-03
Abstract
Som led i CERNs R&D for Beam Dump Facility (BDF) er der fremstillet forskellige target-prototyper: cylindre af ildfaste metaller (materialer der tåler meget høje temperaturer), beklædt med et lag tantal ved hjælp af Varm Isostatisk Presning (HIP), en proces der bruger høj temperatur og højt tryk til at sammenbinde materialer. HIP-processen forventes at efterlade høje restspændinger, det vil sige indre spændinger i materialet efter fremstillingen. At måle disse er afgørende for at validere de termomekaniske simuleringer, der forudsiger, hvordan target-delene opvarmes og deformerer. I afhandlingen blev flere metoder anvendt til at bestemme og forstå fordelingen af restspændinger i delene: hulboring (måling af deformation omkring et lille hul), røntgendiffraktion (måling af forvrængning i krystalstrukturen) og mikroskala FIB (Focused Ion Beam) ring-kerne fræsning kombineret med Digital Image Correlation (DIC) til at følge meget små overfladeforskydninger. Arbejdet er udført i CERNs Engineering-afdeling, Materials and Metrology-gruppen (EN-MME), under vejledning af Josep Busom Descarrega (CERN), Ana Teresa Pérez Fontenla (CERN) og Raino Mikael Larsen (Aalborg Universitet).
As part of CERN's R&D for the Beam Dump Facility (BDF), several target prototypes were manufactured: cylindrical parts made of refractory metals (materials that withstand very high temperatures), clad with a tantalum layer using Hot Isostatic Pressing (HIP), a high-temperature, high-pressure process that bonds materials. The HIP process is expected to leave high residual stresses, meaning internal stresses locked into the material after manufacturing. Measuring these stresses is essential to validate thermo-mechanical simulations that predict how the targets heat up and deform. This thesis used several techniques to determine and understand how these stresses are distributed in the parts: hole drilling (monitoring strain around a small drilled hole), X-ray diffraction (reading microscopic lattice strains), and microscale Focused Ion Beam (FIB) ring-core milling combined with Digital Image Correlation (DIC) to track tiny surface displacements. The work was carried out in CERN's Engineering Department, Materials and Metrology group (EN-MME), under the supervision of Josep Busom Descarrega (CERN), Ana Teresa Pérez Fontenla (CERN) and Raino Mikael Larsen (Aalborg University).
[This abstract was generated with the help of AI]
Keywords
FIB ; DIC ; residual stress ; Beam Dump ; Tantalum
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