| About this Abstract |
| Meeting |
MS&T24: Materials Science & Technology
|
| Symposium
|
Composition–Processing–Microstructure-Property Relationships of Titanium Alloys
|
| Presentation Title |
Surface Engineering Ti Alloys and Stress Impacts on Recrystallization |
| Author(s) |
David Brice, David F. Bahr |
| On-Site Speaker (Planned) |
David Brice |
| Abstract Scope |
Mechanical treatments to create compressive residual stress are used to improve the mechanical performance of alloys. Heat treatments that involve recrystallization commonly decrease residual stresses formed from shot peening. In this study we develop ultra-fine grain structures in three Ti alloys with colony, basket weave, and lamellar precipitates. Microstructures were peened to control residual stresses on the order of 200 to 800 MPa to depths of about 200 microns; the surface nanoindentation hardness after peening was 3-4 GPa (depending on the alloy). Thermal treatment recrystallized the top 2-5 microns of the surface, which lowered residual stresses but formed a grain size between 350 and 700 nm. The resulting hardness increased to 4-5 GPa. The surface hardness was achieved with no decrease in bulk hardness; the compressive residual stress stabilizes the alpha phase in beta Ti alloys, allowing for controlled precipitation and gradients in microstructure with no changes in bulk chemistry. |