Abstract
In crystalline metals and alloys, plasticity occurs due to the movement of mobile dislocations and the yield stress for engineering applications is traditionally quantified based on strain. The onset of irreversible plasticity or “yielding” is generally identified by a deviation from linearity in the stress-strain plot or by some standard convention such as 0.2 % offset strain relative to the “linear elastic response”. In the present work, we introduce a new methodology for the determination of the true yield point based on stress relaxation. We show experimentally that this determination is self-consistent in nature and, as such, provides an objective observation of the very onset of plastic flow. Our designation for yielding is no longer related to the shape of the stress-strain curve but instead reflects the earliest signature of the activation of concerted irreversible dislocation motion in a test specimen under increasing load.
| Original language | English |
|---|---|
| Pages (from-to) | 1095-1107 |
| Number of pages | 13 |
| Journal | Experimental Mechanics |
| Volume | 56 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jul 1 2016 |
Funding
Acknowledgments Research sponsored by the U.S Department of Energy, Office of Fossil Energy, Solid State Energy Conversion Alliance (SECA) Program. Some of the instruments used in this investigation, which are part of the High Temperature Materials Laboratory at ORNL had been acquired with support from the U.S Department of Energy’s Vehicle Technologies Program. Research sponsored by the U.S Department of Energy, Office of Fossil Energy, Solid State Energy Conversion Alliance (SECA) Program. Some of the instruments used in this investigation, which are part of the High Temperature Materials Laboratory at ORNL had been acquired with support from the U.S Department of Energy's Vehicle Technologies Program.
Keywords
- Elastic limit
- Microtesting
- Mobile dislocation
- Yield stress
- Yield surface