James C. Hartley
Published: 1951
Total Pages: 12
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Because the heavy forging industry is one of the most logical fields for the application of non-destructive ultrasonic testing, this method has progressed rapidly and received widespread acceptance. The large masses of metal which are handled lend themselves well to this type of inspection. It is true, further, that forgings are employed where quality requirements are highest and stress conditions most critical. Ultrasonic inspection of such products is justified, not only as a final inspection standard, but also as a routine check during processing. One of the advantages of the ultrasonic inspection method is its ability to indicate the location and approximate magnitude of internal cracks or similar defects which might progress in service, or, acting as stress raisers, cause premature failure of the part. There should be little doubt that the ultrasonic method is entirely practical for such applications and can be employed not only in the investigation of forged steel sections, but for a number of other materials as well. Certain materials, among them the socalled super alloys used for high temperature service for gas turbines and jet engines, exhibit a marked tendency to change ultrasonic transmission dependent upon the degree of refinement of the structure. This fact is useful in determining whether or not satisfactory refinement by forging has been effected.