An EMAT system for non-destructive Inspection of cannon tubes

An EMAT (electromagnetic acoustic transmission) system is currently installed at Watervliet Arsenal where it is used for the relatively simple task of wall thickness measurements. Since this system was designed several years agao, the general capability of EMAT systems has advanced to the point where it is now practical to consider developing an EMAT system for the non-destructive inspection of cannon preforms and tubes. Although it is now generally understood how a flaw detection EMAT system should be designed, there are a few questions related to forged cannon tubes and preforms that must be answered before an EMAT sytem for this inspection task can be designed. Foremost among these questions are what wave mode and operating frequency should be used when one wishes to couple ultrasound through the rough forged surface. Phase I proposes to use an ISA portable EMAT measurement system to perform a series of measurements on cannon preforms and tubes with forged and machined surfaces at an Army facility. Based upon the results of these tests and discussions with Army personnel regarding the stages in cannon tube manufacturing where inspection can or should be performed, Phase II will design, build, install and evaluate an exploratory development EMAT system at an Army facilitye. There is also the possibility of using our Phase I measurements to design, build and evaluate an EMAT system that will eventually be capable of operating on surfaces as hot at 750 degrees C. Phase II includes support to monitor the first year of installed use so that necessary modifications and improvements that become apparent through use can be made. Performance experience with these designs will determine the specifications that can be realized in the commercial and DoD Phase III activities.