NDTnet 1998 Aug, Vol.3 No.8

Abstract

Experimental results of materials characterization by combined ultrasonic methods are presented. Test results concern first the possibilities to classify fatigue behaviours LCF and HCF. Exemplary were investigated shipbuilding steels in tensile fatigue test with R=0.1. The question was solved by analysis of local distribution function of Vickers hardness, of longitudinal ultrasonic velocity and attenuation in Rayleigh region. The distribution functions of HV-30-hardness, ultrasonic velocity and especially of 15 MHz-attenuation were definitely higher in LCF range. The endurance range could be identified by ndt methods.

The separation of fatigue behaviours was succesfull too by use of acoustic emission analysis. Three artificial sources were investigated:HSU-Nielsen-,ball- and Vickers-indenter source. The LCF range could be definitely separated by measuring amplitude, energy, counts and duration time with HSU-Nielsen-source. The spectrum of various artificial sources indicates measurable difference in LCF and HCF ranges. Especially the harmonic analysis of HSU-Nielsen spectrum and the evaluation of distortion factor of Vickers-indenter spectrum permitted definitely a LCF-identification. These results show new possibilities of degree of damage evaluation.

The second group of test results shows possibilities of detection and image formation of microstructural inhomogeneities by ultrasonic highfrequency scanning with FFT. Various types of structural changes in test pieces are three-dimensional illustrated.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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