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Abstract

Remanent life assessment for pressurised components operating at elevated temperatures requires knowledge about the actual degradation of the material. In this paper, studies are presented which address the problem of damage determination in steels exposed to creep. Ultrasonic methods backed up by quantitative metallographic studies have been applied to different materials in order to determine the damage state. For the case where creep damage manifests itself in the cracking of grain boundary facets, a damage variable related to the density and size of the microcracks can be identified. The relationship of the damage variable to ultrasonic measurements and metallographic findings is established. This allows the direct comparison between quantitative metallographic and ultrasonic results. The consistency of the results with predictions from the material models is demonstrated. The applicability of ultrasonic measurements to other types of microstructural damage, i.e., cavity formation on grain boundaries, is discussed. Based on such laboratory tests, some conclusions concerning the advantages and limitations of metallographic and ultrasonic techniques for damage determination are presented.

Additional information

Authors: VON ESTORFF U, JRC Ispra (IT);STAMM H, JRC Ispra (IT)
Bibliographic Reference: Paper presented: Fifth International Conference on Creep, Orlando (US), May 17-21, 1992
Availability: Available from (1) as Paper EN 36728 ORA
Record Number: 199210643 / Last updated on: 1994-12-02
Category: PUBLICATION
Original language: en
Available languages: en
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