Acoustic emission investigation of the ductile to brittle transition in molybdenum

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5958591

James, J B

This investigation shows the effectiveness of making careful acoustic emission measurements in conjunction with in depth metallographic analysis, in order to fully investigate and characterize the cold embrittlement of polycrystalline molybdenum. Acoustic emission measurements were made during a series of tensile tests conducted in the ductile to brittle transition temperature range. The acoustic emission showed continuous emission and burst-type emission. The continuous emission was identified as being due to dislocation breakaway motion and the burst type emission was known to be due to brittle cracking phenomena. The principal cold embrittlement mechanism was believed to be the increasing dislocation pinning strength with decreasing temperature. The increasing dislocation pinning strength was acoustically detectable. Finally, the ability to differentiate between intergranular cracking and transgranular cleavage cracking by studying the fast Fourier transformations of individual waveforms, was demonstrated.

• Research Organization: Denver Univ., CO (USA)
• OSTI ID: 5958591
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ACOUSTIC EMISSION TESTING
ACOUSTIC TESTING
CRYSTALS
DISLOCATION PINNING
DUCTILE-BRITTLE TRANSITIONS
ELEMENTS
EMBRITTLEMENT
MATERIALS TESTING
METALLOGRAPHY
METALS
MOLYBDENUM
NONDESTRUCTIVE TESTING
POLYCRYSTALS
TESTING
TRANSITION ELEMENTS