Predictive Tool for Inclusion Crack Initiation and Growth in Titanium Castings

This study will examine the current understanding on hard alpha inclusion crack initiation and growth in titanium investment castings to determine the required information needed to predict their effects on component durability. Specific focus will bemade on the small crack growth regime for defects of various sizes and locations since it can encompass a majority of the fatigue life. This information will be used to develop an innovative predictive tool that complements current lifing models based onlong crack growth behavior. This study will also generate an accept/reject criteria that will assist in qualifying fracture-critical titanium castings (and improving the manufacturing process) by identifying the most critical inclusions that must befound/removed, thus providing airframe designers with the necessary confidence to expand the use of titanium castings. This project will develop an accept-reject criteria for qualifying fracture-critical titanium castings to allow their expanded use inairframe applications. It will also construct an innovative crack physics-based predictive tool for analyzing the effects of hard alpha inclusions on durability of titanium airframe castings. The tool will allow engineers to account for the potentialimpact of the inclusion failure mode to more confidently assess component durability. It can also be used to intelligently conduct in-service inspection schedules.