TY - JOUR

T1 - Cross-sectional gradients of residual stresses, microstructure and phases in a nitrided steel revealed by 20 µm synchrotron X-ray diffraction

AU - Bodner, Sabine C.

AU - Ziegelwanger, Tobias

AU - Meindlhumer, Michael

AU - Holcova, Jitka

AU - Todt, Juraj

AU - Schell, Norbert

AU - Keckes, Jozef

PY - 2019/10

Y1 - 2019/10

N2 - Cross-sectional gradients of residual stresses, phases, microstructure, composition and mechanical properties within the near-surfaceregions of thermo-chemical treated steels are decisive for the balanced mechanical properties of the final products. In this work, acorrelative cross-sectional micro-analytics is introduced to assess those gradients in an exemplary nitrided steel sample to a depthof ~0.8 mm. Cross-sectional synchrotron X-ray microdiffraction with an energy of 87.1 keV and a spatial resolution of 20 µm wasperformed in transmission diffraction geometry. At first, a methodology to evaluate residual stress magnitudes from two-dimensionalX-ray diffraction data is discussed. The data from a ~2.5 mm long sample gauge volume indicate complex residual stresses andnear-surface microstructure gradients with a maximal compressive stress of ~-400 MPa, descending diffraction peak broadening andvariable crystallographic texture. The results correlate well with the complementary analyses of Vickers micro hardness and samplecross-sectional morphology. In summary, the correlative cross-sectional micro-analytics documents the possibility to determine andcorrelate a variety of mechanical, structural, morphological and chemical sample parameters obtained using cutting-edge characterization approaches. The complex experimental data can be further used to adjust and verify numerical and technological models.

AB - Cross-sectional gradients of residual stresses, phases, microstructure, composition and mechanical properties within the near-surfaceregions of thermo-chemical treated steels are decisive for the balanced mechanical properties of the final products. In this work, acorrelative cross-sectional micro-analytics is introduced to assess those gradients in an exemplary nitrided steel sample to a depthof ~0.8 mm. Cross-sectional synchrotron X-ray microdiffraction with an energy of 87.1 keV and a spatial resolution of 20 µm wasperformed in transmission diffraction geometry. At first, a methodology to evaluate residual stress magnitudes from two-dimensionalX-ray diffraction data is discussed. The data from a ~2.5 mm long sample gauge volume indicate complex residual stresses andnear-surface microstructure gradients with a maximal compressive stress of ~-400 MPa, descending diffraction peak broadening andvariable crystallographic texture. The results correlate well with the complementary analyses of Vickers micro hardness and samplecross-sectional morphology. In summary, the correlative cross-sectional micro-analytics documents the possibility to determine andcorrelate a variety of mechanical, structural, morphological and chemical sample parameters obtained using cutting-edge characterization approaches. The complex experimental data can be further used to adjust and verify numerical and technological models.

M3 - Article

VL - 2019

SP - 7

EP - 11

JO - Metallurgia Italiana

JF - Metallurgia Italiana

SN - 0026-0843

IS - 10

ER -