GEOMETRICAL AND ULTRASONIC MODELING OF HARD-ALPHA DEFECT COMPONENTS IN TITANIUM ALLOYS

摘要

In the last few years, considerable research have been conducted in the Engine Titanium Consortium in the study of naturally occurring hard-alpha flaws found in titanium alloys. One task in the Consortium is undertaking a new approach of bringing state-of-the-art geometrical and ultrasonic models together to assess the improvements in the capabilities to detect hard-alpha inclusions, as quantified by the probability of detection (POD). In the past, such POD studies normally required statistical analysis of large amount of experimental data. However, the rare occurrence of naturally occurring hard-alpha defects and the infeasibility of manufacturing realistic synthetic flaws have made the data acquisition very difficult. To get around this obstacle, a new approach utilizes ultrasonic models to accurately calculate the flaw responses. These require, as input parameters, geometrical models containing the spatial and material descriptions of the flaws. By using models in such way, we are able to examine the effect of flaw morphology on the ultrasonic signals and to establish the maximal knowledge base from the limited naturally occurring flaws. Furthermore, a variety of inspection scenarios can be rapidly simulated to generate the necessary data for the POD evaluation.