Ultrasonic assessment of material degradation by thermal fatigue

Jorma Pitkänen, Pentti Kauppinen, Harri Jeskanen

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

Abstract

Near surface areas can contain many types of defects, material changes and degradation. Materials subjected to thermal fatigue or annealing have been evaluated with a special ultrasonic probe optimised for surface measurements, and with a 0 longitudinal wave probe. Combining measured data from a large area and calculating depths of interest in the sound path (RF-signal) information provides improved estimation of degradation levels. The technique is using a combination of three factors: (1) back-scattered ultrasonic signals and induced leaky Rayleigh wave information), and (2) simple statistical data analysis in combination with (3) an optimised ultrasonic transducer. The back-scattered ultrasonic signal is a measure of the effect of geometrical reflectors such as micro-pores, inclusions, precipitates, segregation, micro-cracks and cracks as well as of back-scattering from phase boundaries during fatigue damaging and increase of degradation inside the material. The leaky Rayleigh wave component is sensitive to surface properties, and especially to cracks. Deep cracks will totally cancel the leaky Rayleigh wave signal.
Original languageEnglish
Title of host publication Competent Design by Castings: Improvements in a Nordic project
Subtitle of host publicationGJUTDESIGN-2005 final seminar
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Pages123-131
ISBN (Electronic)951-38-6299-2
ISBN (Print)951-38-6298-4
Publication statusPublished - 2005
MoE publication typeB3 Non-refereed article in conference proceedings
EventCompetent Design by Castings: Improvements in a Nordic project
: GJUTDESIGN-2005 final seminar
- Espoo, Finland
Duration: 13 Jun 200514 Jun 2005

Publication series

SeriesVTT Symposium
Number237
ISSN0357-9387

Seminar

SeminarCompetent Design by Castings: Improvements in a Nordic project
CountryFinland
CityEspoo
Period13/06/0514/06/05

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    Pitkänen, J., Kauppinen, P., & Jeskanen, H. (2005). Ultrasonic assessment of material degradation by thermal fatigue. In  Competent Design by Castings: Improvements in a Nordic project: GJUTDESIGN-2005 final seminar (pp. 123-131). VTT Technical Research Centre of Finland. VTT Symposium, No. 237 http://www.vtt.fi/inf/pdf/symposiums/2005/S237.pdf