Nondestructive monitoring of the variations in microstructure and residual stress in carburized steels

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2016
Hızlı, Hüseyin
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Service life and performance of the case-hardened machine parts are greatly dependent on the residual stress state in the surface layers which directly affects the fatigue behavior. Recently, all industrial sectors have been requested for a fast and non-destructive determination of residual stress. This study aims to monitor the variations in surface residual stress distributions in the carburized 19CrNi5H steels by means of non-destructive and semi-destructive measurement techniques, Magnetic Barkhausen Noise (MBN), X-Ray Diffraction (XRD), and Electronic Speckle Pattern Interferometry (ESPI) assisted hole drilling. Microstructural investigation by optical and scanning electron microscopy, hardness measurements, and spectroscopy analysis were also conducted. To comprehend the differences in the residual stress distributions, various samples were prepared by applying different duration of carburizing and tempering temperatures. Residual stress measurements carried out by XRD and ESPI assisted hole drilling showed that the compressive residual stress state exists for the case-hardened samples throughout the case depth regions, and the magnitude of the compressive residual stress decreases as the tempering temperature increases. MBN measurements showed that the BN activity increases with decreasing carburization time and increasing tempering temperature. It was concluded that MBN technique could be used to measure the surface residual stress distributions with a proper calibration operation. 
Steel, Steel, Residual stresses., Steel, Nondestructive testing.
http://etd.lib.metu.edu.tr/upload/12620578/index.pdf
https://hdl.handle.net/11511/26004
Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats
H. Hızlı, “Nondestructive monitoring of the variations in microstructure and residual stress in carburized steels,” M.S. - Master of Science, Middle East Technical University, 2016.
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