College - Author 1
College of Engineering
Department - Author 1
Materials Engineering Department
Degree Name - Author 1
BS in Materials Engineering
College - Author 2
College of Engineering
Department - Author 2
Materials Engineering Department
Degree - Author 2
BS in Materials Engineering
Date
6-2020
Primary Advisor
Blair London, College of Engineering, Materials Engineering Department
Abstract/Summary
In this project, fracture surfaces of three titanium investment castings were studied as part of a failure analysis on a TaylorMade metalwood. The crack formation occurred between investment cast Ti 9-1-1 and rolled Ti 6-4 joined by laser beam welding. The microstructure of the Ti 9-1-1 contained alpha colonies in large prior beta grains, while the Ti 6-4 was primarily Widmanstätten in basket weave morphology, refined with subsequent rolling. Over a period of cyclic loading, cracking occurred at the face-sole transition in the metalwoods that had been cast from a certain supplier B, while metalwoods that had undergone similar treatment from another supplier, did not exhibit any cracks. In order to understand the reason for this discrepancy, the fracture surfaces of the cracked metalwoods were examined and imaged with a scanning electron microscope (SEM) in order to study the mode and method of failure. The fracture surfaces examined occurred at a geometric transition, where internal stresses were higher according to FEA. Furthermore, the fracture surfaces revealed lack of fusion in no-fill regions occurring at this transition, where microcracks were observed to be initiating. These pores were most likely the source of fatigue crack initiation, if not, accelerating the propagation of the crack to final rupture.
URL: https://digitalcommons.calpoly.edu/matesp/220