| About this Abstract |
| Meeting |
MS&T24: Materials Science & Technology
|
| Symposium
|
Composition–Processing–Microstructure-Property Relationships of Titanium Alloys
|
| Presentation Title |
Investigating Cold Dwell Fatigue Failure in Dual-Phase Ti Alloys: The Perspective of Hard-Soft Grain Interactions |
| Author(s) |
Baris Yavas, Nadib Akram, Asa Frye, Vasisht Venkatesh, Adam Pilchak, David Furrer, Iuliana Cernatescu, Mark Aindow |
| On-Site Speaker (Planned) |
Baris Yavas |
| Abstract Scope |
Dual-phase alpha/beta Ti alloys are unusually sensitive to early crack nucleation in cold dwell fatigue (CDF). Deformation in the alpha phase occurs most easily by dislocation glide on basal planes, but deformation parallel to [0001] is accommodated by pyramidal <c+a> slip for which the critical resolved shear stress is much higher. This can lead to accumulation of dislocations at the boundaries between grains in hard and soft orientations, causing early crack nucleation. Here we describe a strategy to evaluate the contributions of such effects by electron microscopy analysis of regions in CDF specimens of Ti-6Al-4V tested to failure. The defect microstructure in the grip region reveals the unstrained initial configuration due to thermomechanical processing, whereas the gage section exhibits dislocations induced by general deformation during testing. Analysis of the dislocations immediately below the fracture surface adjacent to the initiation site reveals the configurations involved in crack nucleation and propagation. |