SEDL / STP / STP505-EB / STP35386S

Acoustic Emission During Martensite Formation

Speich, GR
U. S. Steel Corporation Research Laboratory, Monroeville, Pa.

Fisher, RM
U. S. Steel Corporation Research Laboratory, Monroeville, Pa.

Pages: 12    Published: Jan 1972

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Abstract

Martensite formation in an Fe-28Ni-0.11C alloy has been studied using acoustic emission, electrical resistivity, and quantitative metallography techniques. Comparison of these three techniques indicates that about 15 martensite plates are involved in each acoustic emission and that the volume of martensite formed per acoustic emission decreases with increasing volume fraction. The first observation is consistent with the autocatalytic effect and the second with the geometric partitioning effect which are both present in martensitic transformations. Because acoustic emission gives an almost plate by plate record of the martensitic transformation, more detailed studies of the transformation kinetics can be made with this technique than by other techniques such as dilatometry or electrical resistivity.