Date of Award
Master of Science in Aeronautical Engineering
Department of Aeronautics and Astronautics
Ryan O'Hara, PhD.
Beta annealed Ti-6Al-4V has been used extensively in current aerospace platforms due to properties such as high strength to weight ratio. Recent inspections during aircraft production have revealed regions of excessive grain sizes, resulting in quarantined parts and excessive time spent on root cause analysis and risk mitigation efforts. Uncertainty surrounding these parts has led to increased costs and may cause future aircraft production delays. Part manufacturers have intermittently reported problems with abnormal grain growth in these alloys for years, but to date no supplier has been able to determine the source of this microstructural phenomenon. Leveraging common Finite Element Method (FEM) software, sidepressing and upsetting forging processes are simulated to predict internal strain and temperature results for use in identifying regions of localizations effecting grain development. Results were used to guide forging tests in an attempt to reproduce abnormal grain growth in the material. Microscopy and image analysis were used to quantify effects of forging parameters on successful development of coarse grains in sidepressing and upsetting forgings. This work seeks to directly support Air Force Research Laboratory (AFRL)’s Materials and Manufacturing Directorate in determining cause of this ongoing issue.
DTIC Accession Number
Morris, Lee R., "Study of Abnormal Grain Growth in Beta Annealed Ti-6al-4v Forgings" (2018). Theses and Dissertations. 1780.