Correlative cross-sectional characterization of nitrided, carburized and shot-peened steels: synchrotron micro-X-ray diffraction analysis of stress, microstructure and phase gradients: Correlative cross-sectional characterization of nitrided, carburized and shot-peened steels: synchrotron micro-X-ray diffraction analysis of stress, microstructure and phase gradients

Sabine C. Bodner, Michael Meindlhumer, Tobias Ziegelwanger, Haiko Winklmayr, Thomas Hatzenbichler, Christoph Schindelbacher, Bernhard Sartory, Martin Krobath, Werner Ecker, Norbert Schell, Jozef Keckes

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Abstract

Mechanical properties of case modified steels depend decisively on the near-surface gradients of residual stresses, microstructures, phases and chemical composition, which are
generated by the empirically well-established case-hardening techniques. Currently,
however, to obtain the correlation between near-surface structureeproperty gradients,
applied hardening process parameters and steels’ overall performance is a very challenging task. In this work, high-energy synchrotron cross-sectional X-ray diffraction
(CSmicroXRD) using a pencil beam cross-section of 20x500 mm2 and complementary
analytical techniques are used to characterize the surface-to-bulk gradient of (i) a plasma
nitrided steel W300, (ii) a carburized case hardening steel (grade 18CrNiMo7-6) and (iii) a
shot-peened high strength steel, type 300M. CSmicroXRD analysis reveals complex gradients of martensite and austenite phases, residual stresses in both phases, crystallographic
texture and the evolution of diffraction peak broadening with a spatial resolution of
~20 mm. These parameters are correlated with the gradients of hardness, morphologymicrostructure and with the changes in N and C concentrations and/or retained
austenite formation/depletion in all three model samples. Finally, the correlative microanalytics approach indicates the complexity of near surface structure-property relationships as well as the importance of innovative cross-sectional characterization, which allows for assessing gradual near-surface physical and/or chemical changes accompanying
thermo-chemical and mechanical surface treatments
Original languageEnglish
Pages (from-to)1396-1410
Number of pages15
JournalJournal of Materials Research and Technology
Volume11.2021
Issue numberMarch-April
DOIs
Publication statusPublished - 3 Feb 2021

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