Acoustic Emission Determination of Deformation Mechanisms Leading to Failure of Naval Alloys. Volume 1
Final rept. 27 Dec 1979-27 Dec 1982
JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF MATERIALS SCIENCE AND ENGINEERING
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IN this investigation the acoustic emission behavior of three Naval alloy steels HY 80, HY 100 and HY 130 was characterized during tensile elongation and bend type loading. The detection of emissions was accomplished using a very new, state of the art interferometer as well as with a unique piezoelectric transducer. The deformation and fracture of these HY steels was documented via optical and scanning electron microscopy and was correlated with observed emissions in order to determine the generating mechanisms. All three steels investigated were found to exhibit very similar deformation and fracture modes despite a slight difference in microstructures. They also exhibited identical acoustic emission behavior within statistical variances. Their fracture consisted of a very ductile mode involving void coalescence and growth with final failure occurring by knife edge rupture of numerous microligaments between voids. Two major types of acoustic emission were detected. The first occurred prior to yielding and was attributed to dislocation glide over distances above some critical minimum detectable mean free path.
- Marine Engineering