Abstract
A mechanistic understanding of the ductility limit diagrams is of critical importance, but it still remains elusive for a multitude of high temperature materials processing techniques, such as superplastic forming and hot forging. The relevant failure modes for the former are necking at high strain rates and intergranular cavitation at low strain rates, while those for the latter include the competition between longitudinal fracture and shear band. The comparison between the Arrhenius processes for grain boundary diffusion and grain interior creep defines a length scale that dictates whether the grain boundary cavity growth is diffusive or creep-constrained. A quantitative assessment of these damage evolution processes leads to the delineation of the dominant parametric spaces for individual failure modes, and thus superplasticity and forging limit diagrams are derived and compared to available experiments in literature.
| Original language | English |
|---|---|
| Pages (from-to) | 378-386 |
| Number of pages | 9 |
| Journal | Acta Materialia |
| Volume | 194 |
| DOIs | |
| State | Published - Aug 1 2020 |
Funding
The authors are grateful to financial support from the U.S. Department of Energy, Office of Vehicle Technology for the work performed at Oak Ridge National Laboratory, from the U.S. National Science Foundation (DMR-1809640) for the work at University of Tennessee, and from the National Key Research and Development Program of China ( 2016YFB0700300 ) for the work at Central South University. YFG acknowledges fruitful discussions with Prof. T.G. Nieh at University of Tennessee and Dr. T.L. Sham at Argonne National Laboratory. The authors are grateful to financial support from the U.S. Department of Energy, Office of Vehicle Technology for the work performed at Oak Ridge National Laboratory, from the U.S. National Science Foundation (DMR-1809640) for the work at University of Tennessee, and from the National Key Research and Development Program of China (2016YFB0700300) for the work at Central South University. YFG acknowledges fruitful discussions with Prof. T.G. Nieh at University of Tennessee and Dr. T.L. Sham at Argonne National Laboratory.
Keywords
- Forming limit diagram
- High temperature alloys
- Intergranular cavitation
- Necking
- Shear band
- Superplasticity limit diagram