NDTsi 2001 Session: Advances in Non-Ultrasonic NDE Methods
The Influence of Structural Changes in a Material in the Course of Loading on its Acoustic Properties
N. Chausov, A. Lebedev, S. Nedoseka, National Academy of Sciences, Ukraine
ABSTRACT
The paper systematises the investigations into regularities of non-localised damage accumulation in materials conducted at the Institute for Problems of Strength of the National Academy of Sciences of Ukraine with the use of the AE method under various mechanical loading conditions and at different rigidities of the loading system. The objects of the investigation were materials with various structures: tool steels in a quenched state, heat-resistant reactor steels, maraging steel and aluminium alloys with various grain sizes. Correlation between the AE data obtained from specimen testing under conditions of equilibrium deformation involving recording of descending portions of the curves and those obtained from conventional tests appeared to be rather useful for understanding the deformation behaviour of a material in articles with different reserves of elastic energy. It has been verified experimentally that a material after long-term operation exhibits the lowest acoustic activity. The authors have also shown the crack-growth resistance of a material after operation to correlate with some acoustic parameters. Apart from recording ?E signals directly in the process of specimen loading, an additional sonic test was used for specimens after unloading and for metal samples cut out from tested specimens. Analysis of a large amount of data obtained from testing materials under conditions of static and cyclic loading suggests that there exists a stable character of distribution of some acoustic parameters depending on the damage accumulated in the material. The type of these relationships is found to depend appreciably on the mechanical loading conditions, the level of plastic deformation, and operating time. On the basis of the data obtained, the authors formulated a criterion of the estimation of damages accumulated in the material in the course of loading from ?E parameters.
Publication Source: 3nd International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurized Components, November 14-16, 2001, Seville Spain. Publisher: Tecnatom s.a. - [Homepage]
