Experimental Electromagnetic Test Methods for the Nondestructive Evaluation of Carburized Steel Parts

摘要

Several experimental electromagnetic test methods were investigated for application to the nondestructive evaluation of carburized steel parts. The results of the study indicate that an accurate and rapid measure of the case depth of carburized parts can be made based on measurements of the phase of the third harmonic component of the secondary test coil voltage. This test parameter can be relatively insensitive to certain normal process variables. An a.c. inductance bridge was used to obtain measurements indicative of the tempering temperature and free ferrite content of the part. The results of an investigation concerning the influence of retained austenite and residual stress on the magnetic comparator evaluation of carburized steel samples are also reported. Experimental procedures are outlined and results are discussed in terms of potential applications to nondestructive testing problems. (Author)