Improved Ultrasonic Inspection of Titanium Alloy Forging Billets.

Titanium is an important raw material in both aircraft engines and structures. It is also being used in a larger-and-larger size forged billet form. The billets increasing size, in addition to their coarser-grained structures, drastically limit the detection capabilities and reliability of finding small defects when using established ultrasonic techniques along with manually operated commercial instruments. Providing an improved billet inspection to insure greater reliability in the finished part at an improved overall process economy is desirable. Available commercial instruments were evaluated and proven incapable of meeting the critical inspection requirements. An original design for the ultrasonic circuitry, interfaced with a minicomputer, and a data display system which shows the billet in multiple cross-section slices was fabricated. All the detectable defects andor only those which meet or exceed a selected quality control reject criteria, can be displayed. An Ultrasonic Diagnostic Inspection System, UDIS, capable of increased inspection sensitivity, resolution and speed with reduced equipment and operator variability was built and evaluated in this program. The performance characteristics of the system have been well defined by laboratory operations and the feasibility of its application to mill inspection of up to 16-inches diameter and 10-foot length billets has been demonstrated by limited in-plant field trials. In addition, a joint industry billet makeruser team evaluation of the UDIS has also been carried out for the establishment of an improved billet inspection specification. The report also covers recommendations for industry utilization of the UDIS.