Study of Ultrasonic Nondestructive Measuring of Case Depth and Case Hardness

摘要

A high resolution - high gain - high frequency Ultrasonic Reflectoscope technique was successfully applied to give absolute case depth measurement in chromium-molybdenum steel specimens and tank parts. In general, the present ultrasonic breadboard experimental equipment measures absolute case depths between .050 - .060 in. to over 2 ind. for induction, flame, or case carburized steels. The present breadboard measures absolute case depth to approximately plus or minus .012 in., and less than plus or minus .006 in. on case depth variation in the same specimen. Results indicate that ultrasonic case depth measurements may be made with the technique used, on parts of complex geometry such as ball bearing races, etc. The feasibility of case hardness measurements using a Reflectoscope surface mode velocity technique was experimentally and theoretically indicated within limits of area investigated. (Author)