Akademik Veri Yönetim Sistemi
12th European Conf. for NDT, Gothenburg, İsveç, 11 - 15 Haziran 2018, ss.22737
Sign, magnitude and
distribution of residual stresses are extremely important for service
performance and useful life of engineering components. Hence, monitoring their
variation (qualitative approach) and measuring their magnitudes (quantitative
approach) are critical issues in the manufacturing chain. Various destructive
and semi-destructive methods exist to measure residual stresses; however, a
rapid and reliable nondestructive method will be more appropriate for
industrial applications. Recently the magnetic Barkhausen noise (MBN) method
has gained importance for non-destructive determination of residual stresses in
ferromagnetic materials. However, this method has some challenges due to mixed
influences of residual stress and microstructure that require careful
pre-calibration and verification procedures for obtaining reliable quantitative
results. This paper presents the comparison of two MBN procedures for
measurement of surface residual stresses in the carburized steels. Carburizing
is a widely used surface treatment process that creates compressive residual stress
state at the surface-near region, and thus, it remarkably improves the wear
resistance and fatigue performance of low-C low-alloys steels. In the
experiments 19CrNi5H and 21NiCrMo2 samples were carburized for at 900oC
for different periods, and then, tempered in the range of 180oC and
600oC. In the first procedure, the MBN parameters were optimized and
then MBN-r.m.s. values were correlated with the results of XRD stress
measurements. In the second procedure, a pre-calibration technique based on
instantaneous MBN measurements on the samples during tension/compression
loading was applied. The results of two procedures were compared and discussed
by focusing on reliability and applicability of the MBN method for measurement
of residual stresses in industry.