Detection of Residual Stress by Measurement of the Efficiency of the Electromagnetic Generation of Ultrasound,
ROCKWELL INTERNATIONAL THOUSAND OAKS CA SCIENCE CENTER
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Last year it was demonstrated that the efficiency of an electromagnetic transducer is quite sensitive to deformation in low carbon steel, and use of this effect as a nondestructive test for residual stress was proposed. This year several survey experiments designed to more fully define the phenomena have been performed. Basic mechanisms have been studied by comparing the responses of iron, nickel, and invar which represent three substantially different classes of magnetic behavior. Further experiments have been conducted in the technologically important low carbon steels which illustrate the extent to which the measurement is influenced by texture, direction of the stress field, and loads in excess of the yield stress. New stress sensitive parameters derived from the efficiency curves are reported.