Acoustic-emission techniques are beginning to be frequently used as a means of detecting and locating deformation and fracture processes in both metallic and non-metallic engineering structures This has happened despite a relatively poor understanding of the basic physical processes involved in the generation, propagation, and detection of acoustic-emission signals, and of the influence in metals of factors such as composition and microstructure, upon the acoustic emission from different types of deformation and fracture processes The measurement of acoustic emission, potentially, could yield much information about dynamic aspects of these processes However, it is shown that the limitations of existing acoustic-emission recording instrumentation have enabled only qualitative information to be obtained to date Even this data, however, has demonstrated that metallurgical variables greatly affect the acousticemission response of metals, and simple models to account for this are discussed

Acoustic emission for physical examination of metals

Acoustic emission analysis during fatigue crack growth in steel

The sources of acoustic emission in a steel of the A533B composition with low sulphur content have been investigated using two different recording techniques. First, systematic narrow band (0.1–1.0 MHz) measurements were made of acoustic emission activity during uniaxial tensile tests of specimens with a range of controlled microstructures. Mechanical properties and fracto graphic data were analysed, and the most probable deformation and fracture mechanisms deduced for these microstructures. It appears that only a few processes generate detectable emission in this material. For instance, high-velocity dislocation motion can be detected during the yield of slow-cooled or long-tempered specimens, and cleavage fracture in rapidly quenched specimens. A model is presented to relate the magnitude of the emission to the dynamic operation of dislocation and fracture sources. Second, very wide band (25 MHz) calibrated measurements were made of the most energetic emission sources in rapidly quenched materia...

Relationship between microstructure and acoustic emission in Mn-Mo-Ni A533B steel

Nondestructive Evaluation (NDE) may be defined as the determination of the serviceability of a component on the basis of nondestructive measurements. Included are the measurement process, the interpretation of the data in terms of the structure of the component, the prediction of serviceability based on this structure, and the decision whether to accept or reject the part.1,2

T. Ingham

Papers

Acoustic emission characteristics from steels Part 2: Acoustic measurements from fracture toughness tests☆

Acoustic emission characteristics of steels part 1: Acoustic measurements from tensile tests